Upgrading to Async with Entity Framework, Web Api, OData AsyncEntitySetController, Kendo UI, Glimpse & Generic Unit of Work Repository Framework v2.0

Update [11/18/2013]: Added mocked DbContext and DbSet and example Unit Tests using the mocks, download v2.1 https://genericunitofworkandrepositories.codeplex.com.

Thanks to everyone for allowing us to give back to the .NET community, we released Generic Unit of Work and Repository Framework v1.0 for four weeks and received 655 downloads and 4121 views. This post will also serve as the documentation for release v2.0. Thanks to Ivan (@ifarkas) for helping out on the Async development, Ken for debugging the Unit of Work life cycle management for use in web applications with DI & IoC (specifically with Entlib Unity v3.0) and scaling the framework to handle Bounded DbContexts, and to the Glimpse Team (@nickswan ) for helping out on getting Glimpse MVC4 working with MVC5, and providing guidance on how to leverage Glimpse EF6 to view SQL queries from EF.

This will be part six of a six part series of blog posts.

  1. Modern Web Application Layered High Level Architecture with SPA, MVC, Web API, EF, Kendo UI, OData
  2. Generically Implementing the Unit of Work & Repository Pattern with Entity Framework in MVC & Simplifying Entity Graphs
  3. MVC 4, Kendo UI, SPA with Layout, View, Router & MVVM
  4. MVC 4, Web API, OData, EF, Kendo UI, Grid, Datasource (CRUD) with MVVM
  5. MVC 4, Web API, OData, EF, Kendo UI, Binding a Form to Datasource (CRUD) with MVVM
  6. Upgrading to Async with Entity Framework, MVC, OData AsyncEntitySetController, Kendo UI, Glimpse & Generic Unit of Work Repository Framework v2.0

We’ll continue on from the most recent post in this series, you can do a quick review of it here http://blog.longle.net/2013/06/19/mvc-4-web-api-odata-ef-kendo-ui-binding-a-form-to-datasource-crud-with-mvvm-part. Now let’s get right into it, by first taking a look at what was all involved on the server side.

First off let’s take a quick look and the changes we made to our DbContextBase to support Async.

Repository.DbContextBase.cs

Before


    public class DbContextBase : DbContext, IDbContext
    {
        private readonly Guid _instanceId;

        public DbContextBase(string nameOrConnectionString) : base(nameOrConnectionString)
        {
            _instanceId = Guid.NewGuid();
        }

        public Guid InstanceId
        {
            get { return _instanceId; }
        }

        public void ApplyStateChanges()
        {
            foreach (var dbEntityEntry in ChangeTracker.Entries())
            {
                var entityState = dbEntityEntry.Entity as IObjectState;
                if (entityState == null)
                    throw new InvalidCastException("All entites must implement the IObjectState interface, " +
                                                   "this interface must be implemented so each entites state can explicitely determined when updating graphs.");

                dbEntityEntry.State = StateHelper.ConvertState(entityState.State);
            }
        }

        public new IDbSet<T> Set<T>() where T : class
        {
            return base.Set<T>();
        }

        protected override void OnModelCreating(DbModelBuilder builder)
        {
            builder.Conventions.Remove<PluralizingTableNameConvention>();
            base.OnModelCreating(builder);
        }

        public override int SaveChanges()
        {
            ApplyStateChanges();
            return base.SaveChanges();
        }
    }

After:


    public class DbContextBase : DbContext, IDbContext
    {
        private readonly Guid _instanceId;

        public DbContextBase(string nameOrConnectionString) : base(nameOrConnectionString)
        {
            _instanceId = Guid.NewGuid();
        }

        public Guid InstanceId
        {
            get { return _instanceId; }
        }

        public void ApplyStateChanges()
        {
            foreach (DbEntityEntry dbEntityEntry in ChangeTracker.Entries())
            {
                var entityState = dbEntityEntry.Entity as IObjectState;
                if (entityState == null)
                    throw new InvalidCastException("All entites must implement the IObjectState interface, " +
                                                   "this interface must be implemented so each entites state can explicitely determined when updating graphs.");

                dbEntityEntry.State = StateHelper.ConvertState(entityState.State);
            }
        }

        public new IDbSet<T> Set<T>() where T : class
        {
            return base.Set<T>();
        }

        public override int SaveChanges()
        {
            ApplyStateChanges();
            return base.SaveChanges();
        }

        public override Task<int> SaveChangesAsync()
        {
            ApplyStateChanges();
            return base.SaveChangesAsync();
        }

        public override Task<int> SaveChangesAsync(CancellationToken cancellationToken)
        {
            ApplyStateChanges();
            return base.SaveChangesAsync(cancellationToken);
        }

        protected override void OnModelCreating(DbModelBuilder builder)
        {
            builder.Conventions.Remove<PluralizingTableNameConvention>();
            base.OnModelCreating(builder);
        }
    }

All that was needed here was to expose all the DbContext Async save operations so that we could use with our IUnitOfWork implementation, and also not forgetting to invoke our ApplyStateChanges so that we are managing the different states each entity could have when dealing with graphs.

Next up, are the enhancements made to our Repository.cs, so that our generic repositories can leverage the Async goodness as well.

Repostiory.Repository.cs

Before:


 public class Repository<TEntity> : IRepository<TEntity> where TEntity : class
    {
        private readonly Guid _instanceId;
        internal IDbContext Context;
        internal IDbSet<TEntity> DbSet;

        public Repository(IDbContext context)
        {
            Context = context;
            DbSet = context.Set<TEntity>();
            _instanceId = Guid.NewGuid();
        }

        public Guid InstanceId
        {
            get { return _instanceId; }
        }

        public virtual TEntity FindById(object id)
        {
            return DbSet.Find(id);
        }

        public virtual void InsertGraph(TEntity entity)
        {
            DbSet.Add(entity);
        }

        public virtual void Update(TEntity entity)
        {
            DbSet.Attach(entity);
        }

        public virtual void Delete(object id)
        {
            var entity = DbSet.Find(id);
            ((IObjectState) entity).State = ObjectState.Deleted;
            Delete(entity);
        }

        public virtual void Delete(TEntity entity)
        {
            DbSet.Attach(entity);
            DbSet.Remove(entity);
        }

        public virtual void Insert(TEntity entity)
        {
            DbSet.Attach(entity);
        }

        public virtual IRepositoryQuery<TEntity> Query()
        {
            var repositoryGetFluentHelper = new RepositoryQuery<TEntity>(this);
            return repositoryGetFluentHelper;
        }

        internal IQueryable<TEntity> Get(
            Expression<Func<TEntity, bool>> filter = null,
            Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
            List<Expression<Func<TEntity, object>>> includeProperties = null,
            int? page = null,
            int? pageSize = null)
        {
            IQueryable<TEntity> query = DbSet;

            if (includeProperties != null)
                includeProperties.ForEach(i => query = query.Include(i));

            if (filter != null)
                query = query.Where(filter);

            if (orderBy != null)
                query = orderBy(query);

            if (page != null && pageSize != null)
                query = query
                    .Skip((page.Value - 1)*pageSize.Value)
                    .Take(pageSize.Value);

            var results = query;

            return results;
        }
    }

After:


    public class Repository<TEntity> : IRepository<TEntity> where TEntity : class
    {
        private readonly Guid _instanceId;
        private readonly DbSet<TEntity> _dbSet;

        public Repository(IDbContext context)
        {
            _dbSet = context.Set<TEntity>();
            _instanceId = Guid.NewGuid();
        }

        public Guid InstanceId
        {
            get { return _instanceId; }
        }

        public virtual TEntity Find(params object[] keyValues)
        {
            return _dbSet.Find(keyValues);
        }

        public virtual async Task<TEntity> FindAsync(params object[] keyValues)
        {
            return await _dbSet.FindAsync(keyValues);
        }

        public virtual async Task<TEntity> FindAsync(CancellationToken cancellationToken, params object[] keyValues)
        {
            return await _dbSet.FindAsync(cancellationToken, keyValues);
        }

        public virtual IQueryable<TEntity> SqlQuery(string query, params object[] parameters)
        {
            return _dbSet.SqlQuery(query, parameters).AsQueryable();
        }

        public virtual void InsertGraph(TEntity entity)
        {
            _dbSet.Add(entity);
        }

        public virtual void Update(TEntity entity)
        {
            _dbSet.Attach(entity);
            ((IObjectState)entity).State = ObjectState.Modified;
        }

        public virtual void Delete(object id)
        {
            var entity = _dbSet.Find(id);
            Delete(entity);
        }

        public virtual void Delete(TEntity entity)
        {
            _dbSet.Attach(entity);
            ((IObjectState)entity).State = ObjectState.Deleted;
            _dbSet.Remove(entity);
        }

        public virtual void Insert(TEntity entity)
        {
            _dbSet.Attach(entity);
            ((IObjectState)entity).State = ObjectState.Added;
        }

        public virtual IRepositoryQuery<TEntity> Query()
        {
            var repositoryGetFluentHelper = new RepositoryQuery<TEntity>(this);
            return repositoryGetFluentHelper;
        }

        internal IQueryable<TEntity> Get(
            Expression<Func<TEntity, bool>> filter = null,
            Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
            List<Expression<Func<TEntity, object>>> includeProperties = null,
            int? page = null,
            int? pageSize = null)
        {
            IQueryable<TEntity> query = _dbSet;

            if (includeProperties != null)
            {
                includeProperties.ForEach(i => query = query.Include(i));
            }

            if (filter != null)
            {
                query = query.Where(filter);
            }

            if (orderBy != null)
            {
                query = orderBy(query);
            }

            if (page != null && pageSize != null)
            {
                query = query
                    .Skip((page.Value - 1)*pageSize.Value)
                    .Take(pageSize.Value);
            }
            return query;
        }

        internal async Task<IEnumerable<TEntity>> GetAsync(
                    Expression<Func<TEntity, bool>> filter = null,
                    Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
                    List<Expression<Func<TEntity, object>>> includeProperties = null,
                    int? page = null,
                    int? pageSize = null)
        {
            return Get(filter, orderBy, includeProperties, page, pageSize).AsEnumerable();
        }
    }

Here we’ve exposed the FindAsync methods from DbSet, so our Repositories can make use of them, and we’ve also wrapped implemented an Async implementation of our Get() method so that we can use it in our new Web Api ProductController.cs later.

Important note: here is that although our method is named GetAsync, it is not truly performing an Async interaction, this is due to the fact that if we were to use ToListAsync(), we would already executed the the query prior to OData applying it’s criteria to the execution plan e.g. if the OData query was requesting 10 records for page 2 of a grid from a Products table that had 1000 rows in it, ToListAsync() would have actually pulled a 1000 records from SQL to the web server and at that time do a skip 10 and take 20 from the collection of Products with 1000 objects. What we want is for this to happen on the SQL Server, meaning, SQL query the Products table, skip the first 10, and take next 10 records and only send those 10 records over to the web server, which will eventually surface into the Grid in the user’s browsers. Hence we are favoring payload size (true SQL Server side paging) going over the wire, vs. a true Async call to SQL.

Northwind.Web.Areas.Spa.Api.ProductController.cs

Before:


    public class ProductController : EntitySetController<Product, int>
    {
        private readonly IUnitOfWork _unitOfWork;

        public ProductController(IUnitOfWork unitOfWork)
        {
            _unitOfWork = unitOfWork;
        }

        public override IQueryable<Product> Get()
        {
            return _unitOfWork.Repository<Product>().Query().Get();
        }

        protected override Product GetEntityByKey(int key)
        {
            return _unitOfWork.Repository<Product>().FindById(key);
        }

        protected override Product UpdateEntity(int key, Product update)
        {
            update.State = ObjectState.Modified;
            _unitOfWork.Repository<Product>().Update(update);
            _unitOfWork.Save();

            return update;
        }

        public override void Delete([FromODataUri] int key)
        {
            _unitOfWork.Repository<Product>().Delete(key);
            _unitOfWork.Save();
        }

        protected override void Dispose(bool disposing)
        {
            _unitOfWork.Dispose();
            base.Dispose(disposing);
        }
    }
 

After:

Note: Don’t be overwhelmed by how much more code there is in the “After” for our new ProductController that now inherits AsyncEntitySetController. I’ll explain later, what all the other Actions are there for. For now, please keep in mind there are only a few of these Actions that are actually required for the use case on the live demo site. The only Actions (methods) that are needed for our use case are as follows:

  • Task<IEnumerable> Get()
  • Task Get([FromODataUri] int key)
  • Task UpdateEntityAsync(int key, Product update)
  • Task Delete([FromODataUri] int key)

[ODataNullValue]
public class ProductController : AsyncEntitySetController<Product, int>
{
    private readonly IUnitOfWork _unitOfWork;

    public ProductController(IUnitOfWork unitOfWork)
    {
        _unitOfWork = unitOfWork;
    }

    protected override void Dispose(bool disposing)
    {
        _unitOfWork.Dispose();
        base.Dispose(disposing);
    }

    protected override int GetKey(Product entity)
    {
        return entity.ProductID;
    }

[Queryable]
public override async Task<IEnumerable<Product>> Get()
{
return await _unitOfWork.Repository<Product>().Query().GetAsync();
}

    [Queryable]
    public override async Task<HttpResponseMessage> Get([FromODataUri] int key)
    {
        var query = _unitOfWork.Repository<Product>().Query().Filter(x => x.ProductID == key).Get();
        return Request.CreateResponse(HttpStatusCode.OK, query);
    }

    ///// <summary>
    ///// Retrieve an entity by key from the entity set.
    ///// </summary>
    ///// <param name="key">The entity key of the entity to retrieve.</param>
    ///// <returns>A Task that contains the retrieved entity when it completes, or null if an entity with the specified entity key cannot be found in the entity set.</returns>
    [Queryable]
    protected override async Task<Product> GetEntityByKeyAsync(int key)
    {
        return await _unitOfWork.Repository<Product>().FindAsync(key);
    }

    protected override async Task<Product> CreateEntityAsync(Product entity)
    {
        if (entity == null)
            throw new HttpResponseException(HttpStatusCode.BadRequest);
            
        _unitOfWork.Repository<Product>().Insert(entity);
        await _unitOfWork.SaveAsync();
        return entity;
    }

    protected override async Task<Product> UpdateEntityAsync(int key, Product update)
    {
        if (update == null)
            throw new HttpResponseException(HttpStatusCode.BadRequest);
            
        if (key != update.ProductID)
            throw new HttpResponseException(Request.CreateODataErrorResponse(HttpStatusCode.BadRequest, new ODataError { Message = "The supplied key and the Product being updated do not match." }));

        try
        {
            update.State = ObjectState.Modified;
            _unitOfWork.Repository<Product>().Update(update);
            var x = await _unitOfWork.SaveAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            throw new HttpResponseException(HttpStatusCode.BadRequest);
        }
        return update;
    }

    // PATCH <controller>(key)
    /// <summary>
    /// Apply a partial update to an existing entity in the entity set.
    /// </summary>
    /// <param name="key">The entity key of the entity to update.</param>
    /// <param name="patch">The patch representing the partial update.</param>
    /// <returns>A Task that contains the updated entity when it completes.</returns>
    protected override async Task<Product> PatchEntityAsync(int key, Delta<Product> patch)
    {
        if (patch == null)
            throw new HttpResponseException(HttpStatusCode.BadRequest);

        if (key != patch.GetEntity().ProductID)
            throw Request.EntityNotFound();

        var entity = await _unitOfWork.Repository<Product>().FindAsync(key);

        if (entity == null)
            throw Request.EntityNotFound();

        try
        {
            patch.Patch(entity);
            await _unitOfWork.SaveAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            throw new HttpResponseException(HttpStatusCode.Conflict);
        }
        return entity;
    }

    public override async Task Delete([FromODataUri] int key)
    {
        var entity = await _unitOfWork.Repository<Product>().FindAsync(key);

        if (entity == null)
            throw Request.EntityNotFound();

        _unitOfWork.Repository<Product>().Delete(entity);

        try
        {
            await _unitOfWork.SaveAsync();
        }
        catch (Exception e)
        { 
            throw new HttpResponseException(
                new HttpResponseMessage(HttpStatusCode.Conflict)
                {
                    StatusCode = HttpStatusCode.Conflict, 
                    Content = new StringContent(e.Message), 
                    ReasonPhrase = e.InnerException.InnerException.Message
                });
        }
    }

    #region Links
    // Create a relation from Product to Category or Supplier, by creating a $link entity.
    // POST <controller>(key)/$links/Category
    // POST <controller>(key)/$links/Supplier
    /// <summary>
    /// Handle POST and PUT requests that attempt to create a link between two entities.
    /// </summary>
    /// <param name="key">The key of the entity with the navigation property.</param>
    /// <param name="navigationProperty">The name of the navigation property.</param>
    /// <param name="link">The URI of the entity to link.</param>
    /// <returns>A Task that completes when the link has been successfully created.</returns>
    [AcceptVerbs("POST", "PUT")]
    public override async Task CreateLink([FromODataUri] int key, string navigationProperty, [FromBody] Uri link)
    {
        var entity = await _unitOfWork.Repository<Product>().FindAsync(key);

        if (entity == null)
            throw Request.EntityNotFound();
            
        switch (navigationProperty)
        {
            case "Category":
                var categoryKey = Request.GetKeyValue<int>(link);
                var category = await _unitOfWork.Repository<Category>().FindAsync(categoryKey);

                if (category == null)
                    throw Request.EntityNotFound();
                    
                    entity.Category = category;
                break;

            case "Supplier":
                var supplierKey = Request.GetKeyValue<int>(link);
                var supplier = await _unitOfWork.Repository<Supplier>().FindAsync(supplierKey);

                if (supplier == null)
                    throw Request.EntityNotFound();
                    
                    entity.Supplier = supplier;
                break;

            default:
                await base.CreateLink(key, navigationProperty, link);
                break;
        }
        await _unitOfWork.SaveAsync();
    }

    // Remove a relation, by deleting a $link entity
    // DELETE <controller>(key)/$links/Category
    // DELETE <controller>(key)/$links/Supplier
    /// <summary>
    /// Handle DELETE requests that attempt to break a relationship between two entities.
    /// </summary>
    /// <param name="key">The key of the entity with the navigation property.</param>
    /// <param name="relatedKey">The key of the related entity.</param>
    /// <param name="navigationProperty">The name of the navigation property.</param>
    /// <returns>Task.</returns>
    public override async Task DeleteLink([FromODataUri] int key, string relatedKey, string navigationProperty)
    {
        var entity = await _unitOfWork.Repository<Product>().FindAsync(key);

        if (entity == null)
            throw Request.EntityNotFound();

        switch (navigationProperty)
        {
            case "Category":
                entity.Category = null;
                break;

            case "Supplier":
                entity.Supplier = null;
                break;

            default:
                await base.DeleteLink(key, relatedKey, navigationProperty);
                break;
        }

        await _unitOfWork.SaveAsync();
    }

    // Remove a relation, by deleting a $link entity
    // DELETE <controller>(key)/$links/Category
    // DELETE <controller>(key)/$links/Supplier
    /// <summary>
    /// Handle DELETE requests that attempt to break a relationship between two entities.
    /// </summary>
    /// <param name="key">The key of the entity with the navigation property.</param>
    /// <param name="navigationProperty">The name of the navigation property.</param>
    /// <param name="link">The URI of the entity to remove from the navigation property.</param>
    /// <returns>Task.</returns>
    public override async Task DeleteLink([FromODataUri] int key, string navigationProperty, [FromBody] Uri link)
    {
        var entity = await _unitOfWork.Repository<Product>().FindAsync(key);

        if (entity == null)
            throw Request.EntityNotFound();

        switch (navigationProperty)
        {
            case "Category":
                entity.Category = null;
                break;

            case "Supplier":
                entity.Supplier = null;
                break;

            default:
                await base.DeleteLink(key, navigationProperty, link);
                break;
        }

        await _unitOfWork.SaveAsync();
    }
    #endregion Links

    public override async Task<HttpResponseMessage> HandleUnmappedRequest(ODataPath odataPath)
    {
        //TODO: add logic and proper return values
        return Request.CreateResponse(HttpStatusCode.NoContent, odataPath);
    }

    #region Navigation Properties
    public async Task<Category> GetCategory(int key)
    {
        var entity = await _unitOfWork.Repository<Product>().FindAsync(key);

        if (entity == null)
            throw Request.EntityNotFound();
            
        return entity.Category;
    }

    public async Task<Supplier> GetSupplier(int key)
    {
        var entity = await _unitOfWork.Repository<Product>().FindAsync(key);

        if (entity == null)
            throw Request.EntityNotFound();
            
        return entity.Supplier;
    }
    #endregion Navigation Properties
}

Quickly looking at this, one can realize there is a lot more code than our pre-Async implementation. Well don’t be alarmed, there’s a lot of code here that wasn’t required to support our use case in the live demo (http://longle.azurewebsites.net), however we wanted to take the extra step so that we can really grasp on how to work with entity graphs with OData by leveraging the ?$expand query string parameter.

We’ll leave all the other that Actions that aren’t actually required for our use case on the live demo SPA as is, so we can see how to deep load your entity graph with OData and Web Api. We’ve included some pre-baked clickable OData URL’s (queries) on the View so that you can actually click and see the response payload in your browser (you’ll have to use Chrome or Firefox, IE has some catching up to do here).

*Click on image
10-9-2013 8-51-43 PM

Now let’s do a deep dive on the our Async Get() Action in our Controller.


[Queryable]
 
public override async Task<IEnumerable<Product>> Get()
{
    return await _unitOfWork.Repository<Product>().Query().GetAsync();
}
 

My initial thought when seeing this this Action (signature) is that it’s not IQueryable?! Which means that the SQL plan from EF has already been executed before OData has an opportunity to apply it’s criteria to the query plan! Well that’s not the case, we outfitted the Project with Glimpse and Glimpse EF6 to actually see what SQL queries were being sent over the wire.

So let’s take a look at the loading up our Kendo UI Grid with the awesomeness of Glimpse running. Since our View is built with Kendo UI, and we know it’s invoking Ajax calls to request data, we’ll click on the Ajax panel on the Glimpse HUD.

*Click on image
10-9-2013 7-30-56 PM

Now with the HUD automatically switching to standard view we can see all the Ajax requests that our View made, we are interested in the OData request that was made to hydrate our Kendo Grid.

*Click on image
10-9-2013 8-04-32 PM

After clicking on Inspect for the Ajax OData request, we see that menu buttons buttons that have tracing data for that request start to actual blink…! One of them being SQL, so let’s click on it.

*Click on image
10-9-2013 8-32-10 PM

Ladies and gentlemen, I kid you not, behold this is the actual SQL query that was from our Unit Of Work -> Repostiory -> Entity Framework 6 -> T-SQL, that was actually sent to SQL Server (actually in our case SQL Server CE, so that the live demo can be complete free with Azure Website without the need to pay for SQL Azure). BTW, we just scratching the surface of what Glimpse can do, the list is pretty much endless e.g. displays MVC Routes, Actions, Tracing, Environment Variables, MVC Views, and performance metrics for pretty much all of them, etc.

Now back to the topic at hand, we can definitively see that although our Action and our Repository are returning IEnumerable:

Get Action the Kendo UI Datasource is calling, which returns IEnumerable.


[Queryable] 
 
public override async Task<IEnumerable<Product>> Get()
{
    return await _unitOfWork.Repository<Product>().Query().GetAsync();
}
 

Repository method the Action is calling, which also returns IEnumerable.


        internal async Task<IEnumerable<TEntity>> GetAsync(
                    Expression<Func<TEntity, bool>> filter = null,
                    Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
                    List<Expression<Func<TEntity, object>>> includeProperties = null,
                    int? page = null,
                    int? pageSize = null)
        {
            return Get(filter, orderBy, includeProperties, page, pageSize).AsEnumerable();
        }
 

The query plan is still valid, meaning it’s selecting only the rows (10 records to be exact) that the Grid is requesting for page one (1) of the Grid. So how is this happening? Well we’ve decorated our action with the [Queryable] attribute, so OData and Web Api is able to perform it’s magic together during run-time in the ASP.NET HTTP pipeline.

T-SQL that’s being sent over the wire, courtesy of Glimpse EF6

 
 
SELECT TOP (10 /* @p__linq__0 */) 
    [Extent1].[Product ID] AS [Product ID], 
    [Extent1].[Product Name] AS [Product Name], 
    [Extent1].[Supplier ID] AS [Supplier ID], 
    [Extent1].[Category ID] AS [Category ID], 
    [Extent1].[Quantity Per Unit] AS [Quantity Per Unit], 
    [Extent1].[Unit Price] AS [Unit Price], 
    [Extent1].[Units In Stock] AS [Units In Stock], 
    [Extent1].[Units On Order] AS [Units On Order], 
    [Extent1].[Reorder Level] AS [Reorder Level], 
    [Extent1].[Discontinued] AS [Discontinued]
    FROM [Products] AS [Extent1]
    ORDER BY [Extent1].[Product ID] ASC
 

Now, let’s cover at a high-level on all the Actions that aren’t required for our live demo use case, which are mostly to support Navigation Properties e.g. Product.Supplier, Product.Category, etc.

The $expand query string parameter allows us to hydrate complex navigation property types. For example in our case when we query for a Product, and Product has a property of Category and we the Category to be hydrated with its data we would leverage the $expand querystring parameter to do this, click this Url : http://longle.azurewebsites.net/odata/Product/?$inlinecount=allpages&$orderby=ProductName&$skip=1&$top=2&$expand=Category&$select=ProductID,ProductName,Category/CategoryID,Category/CategoryName to see the $expand in action.

T-SQL that’s being sent over the wire, again, courtesy of Glimpse EF6

 
 
SELECT TOP (2 /* @p__linq__1 */) 
    [top].[Product ID] AS [Product ID], 
    [top].[C1] AS [C1], 
    [top].[C2] AS [C2], 
    [top].[Product Name] AS [Product Name], 
    [top].[C3] AS [C3], 
    [top].[C4] AS [C4], 
    [top].[C5] AS [C5], 
    [top].[C6] AS [C6], 
    [top].[Category Name] AS [Category Name], 
    [top].[C7] AS [C7], 
    [top].[Category ID] AS [Category ID], 
    [top].[C8] AS [C8]
    FROM ( SELECT [Project1].[Product ID] AS [Product ID], [Project1].[Product Name] AS [Product Name], [Project1].[Category ID] AS [Category ID], [Project1].[Category Name] AS [Category Name], [Project1].[C1] AS [C1], [Project1].[C2] AS [C2], [Project1].[C3] AS [C3], [Project1].[C4] AS [C4], [Project1].[C5] AS [C5], [Project1].[C6] AS [C6], [Project1].[C7] AS [C7], [Project1].[C8] AS [C8]
        FROM ( SELECT 
            [Extent1].[Product ID] AS [Product ID], 
            [Extent1].[Product Name] AS [Product Name], 
            [Extent1].[Category ID] AS [Category ID], 
            [Extent2].[Category Name] AS [Category Name], 
            N'ace5ad31-e3e9-4cde-9bb8-d75fced846fa' AS [C1], 
            N'ProductName' AS [C2], 
            N'ProductID' AS [C3], 
            N'Category' AS [C4], 
            N'ace5ad31-e3e9-4cde-9bb8-d75fced846fa' AS [C5], 
            N'CategoryName' AS [C6], 
            N'CategoryID' AS [C7], 
            CASE WHEN ([Extent1].[Category ID] IS NULL) THEN cast(1 as bit) ELSE cast(0 as bit) END AS [C8]
            FROM  [Products] AS [Extent1]
            LEFT OUTER JOIN [Categories] AS [Extent2] ON [Extent1].[Category ID] = [Extent2].[Category ID]
        )  AS [Project1]
        ORDER BY [Project1].[Product Name] ASC, [Project1].[Product ID] ASC
        OFFSET 1 /* @p__linq__0 */ ROWS 
    )  AS [top]
 

Product results with Categories hydrated

 
  
{
  "odata.metadata":"http://longle.azurewebsites.net/odata/$metadata#Product&$select=ProductID,ProductName,Category/CategoryID,Category/CategoryName","odata.count":"77","value":[
    {
      "Category":{
        "CategoryID":2,"CategoryName":"Condiments"
      },"ProductID":3,"ProductName":"Aniseed Syrup"
    },{
      "Category":{
        "CategoryID":8,"CategoryName":"Seafood"
      },"ProductID":40,"ProductName":"Boston Crab Meat"
    }
  ]
} 
 

We can really see the power of Web Api and OData now, we’re actually able to query for Products (skip the first and take the next two) and request that Category be hydrated but specifically only the CategoryId and Name and none of the other fields.

Sample Application Client Side (Kendo UI) Tweaks

We’ve polished the UI/UX a bit, relocated Edit, Edit Details, and Delete buttons out of the rows into the Grid Toolbar (header) to make better use of the Grid real estate, using Kendo’s Template Framework, which illustrates how flexible Kendo UI can be. The app has been upgraded to, Twitter Bootstrap as by leveraging the new out of the box MVC Project Templates in Visual Studio 2013 (Preview) and changing the Kendo UI theme to Bootstrap to match.

All Kendo Views which are remotely loaded on demand into the SPA are now actually MVC Razor Views, the Kendo Router remotely loads views by traditional MVC routes e.g.
{controller}/{action}/{id} vs. what was in the previous post (http://blog.longle.net/2013/06/17/mvc-4-kendo-ui-spa-with-layout-router-mvvm/) which was just serving up raw *.html pages. This has been a request for devs that are making the transition from server side MVC development into the SPA realm, and had .NET libraries they still wanted to make use of and leverage in their their Controllers, and Razor Views for SPA’s. Obviously, all Views and ViewModel binding on the client-side are done with with Kendo’s MVVM Framework.

Northwind.Web/Areas/Spa/Content/Views/products.html

Before (non Razor, just plain *.html pages were used for SPA):

 
@{
    ViewBag.Title = "Products";
    Layout = "";
}
<div class="row">
    <div class="span5">
        <h2>Technlogy Stack</h2>
        <h3><a href="http://blog.longle.net">blog.longle.net</a></h3>
        <p>ASP.NET MVC 4, Web API, OData, Entity Framework 6 CTP, EntityFramework CE 6 RC1, Visual Studio 2013 Preview, Sql Server CE, Twitter Bootstrap, Kendo UI Web, Azure Website PaaS (<a href="http://www.windowsazure.com/en-us/develop/net/aspnet/" target="blank">free!</a>)</p>
        <br />
        <p><a class="btn" href="http://go.microsoft.com/fwlink/?LinkId=301865">Learn more &raquo;</a></p>
    </div>
</div>

<br /><br />
<div class="k-content" style="width: 100%">
    <div id="view">
        <div id="productGrid"
             data-role="grid"
             data-sortable="true"
             data-pageable="true"
             data-filterable="true"
             data-bind="source: dataSource, events: { dataBound: dataBound, change: onChange }"
             data-editable="inline"
             data-selectable="true"
             data-toolbar='[ { template: $("#toolbar").html() } ]'
             data-columns='[
                    { field: "ProductID", title: "ID", width: "50px" },
                    { field: "ProductName", title: "Name"},
                    { field: "QuantityPerUnit", title: "Quantity", width: "200px" },
                    { field: "UnitsInStock", title: "Stock", width: "90px" },
                    { field: "UnitPrice", title: "Price", format: "{0:c}", width: "100px" },
                    { field: "Discontinued", width: "150px" } ]'>
        </div>
    </div>
    <h3>Use Chrome or Firefox and click on OData (queries) Urls below for example results.</h3>
    <ul>
        <li><a href="/odata/$metadata">/odata/$metadata</a></li>
        <li><a href="/odata/Product">/odata/Product</a></li>
        <li><a href="/odata/Product/?$select=ProductID,ProductName">/odata/Product/?$select=ProductID,ProductName</a></li>
        <li><a href="/odata/Product/?$orderby=ProductName&$skip=1&$top=2">/odata/Product/?$orderby=ProductName&$skip=1&$top=2</a></li>
        <li><a href="/odata/Product/?$orderby=ProductName&$skip=1&$top=2">/odata/Product/?$orderby=ProductName&$skip=1&$top=2</a></li>
        <li><a href="/odata/Product/?$inlinecount=allpages&$filter=UnitPrice ge 20">/odata/Product/?$inlinecount=allpages&$filter=UnitPrice ge 20</a></li>
        <li><a href="/odata/Product/?$expand=Category">/odata/Product/?$expand=Category</a></li>
        <li><a href="/odata/Product/?$expand=Category&$select=ProductID,ProductName,Category/CategoryID,Category/CategoryName">/odata/Product/?$expand=Category&$select=ProductID,ProductName,Category/CategoryID,Category/CategoryName</a></li>
        <li><a href="/odata/Product/?$inlinecount=allpages&$orderby=ProductName&$skip=1&$top=2&$expand=Category&$select=ProductID,ProductName,Category/CategoryID,Category/CategoryName">/odata/Product/?$inlinecount=allpages&$orderby=ProductName&$skip=1&$top=2&$expand=Category&$select=ProductID,ProductName,Category/CategoryID,Category/CategoryName</a></li>
    </ul>
</div>

<script type="text/x-kendo-template" id="toolbar">
    <div class="toolbar">
        <a class="k-button" onclick="edit(event);"><span class="k-icon k-i-tick"></span>Edit</a>
        <a class="k-button" onclick="destroy(event);"><span class="k-icon k-i-tick"></span>Delete</a>
        <a class="k-button" onclick="details(event);"><span class="k-icon k-i-tick"></span>Edit Details</a>
    </div>
    <div class="toolbar" style="display:none">
        <a class="k-button" onclick="save(event);"><span class="k-icon k-i-tick"></span>Save</a>
        <a class="k-button" onclick="cancel(event);"><span class="k-icon k-i-tick"></span>Cancel</a>
    </div>
</script>

<script>
    var lastSelectedDataItem;

    var save = function (event) {
        onClick(event, function (grid) {
            grid.saveRow();
            $(".toolbar").toggle();
        });
    };

    var cancel = function (event) {
        onClick(event, function (grid) {
            grid.cancelRow();
            $(".toolbar").toggle();
        });
    };

    var details = function (event) {
        onClick(event, function (grid, row, dataItem) {
            window.location.href = '#/edit/' + dataItem.ProductID;
        });
    };

    var edit = function (event) {
        onClick(event, function (grid, row) {
            grid.editRow(row);
            $(".toolbar").toggle();
        });
    };

    var destroy = function (event) {
        onClick(event, function (grid, row, dataItem) {
            grid.dataSource.remove(dataItem);
            grid.dataSource.sync();
        });
    };

    var onClick = function (event, delegate) {
        event.preventDefault();
        var grid = $("#productGrid").data("kendoGrid");
        var selectedRow = grid.select();
        var dataItem = grid.dataItem(selectedRow);
        if (selectedRow.length > 0)
            delegate(grid, selectedRow, dataItem);
        else
            alert("Please select a row.");
    };

    var Product = kendo.data.Model.define({
        id: "ProductID",
        fields: {
            ProductID: { type: "number", editable: false, nullable: true },
            ProductName: { type: "string", validation: { required: true } },
            QuantityPerUnit: { type: "string", validation: { required: true } },
            UnitsInStock: { type: "number", validation: { required: true } },
            UnitPrice: { type: "number", validation: { required: true, min: 1 } },
            Discontinued: { type: "boolean" }
        }
    });

    var baseUrl = "/odata/Product";

    var dataSource = new kendo.data.DataSource({
        type: "odata",
        transport: {
            read: {
                url: baseUrl,
                dataType: "json"
            },
            update: {
                url: function (data) {
                    return baseUrl + "(" + data.ProductID + ")";
                },
                dataType: "json"
            },
            destroy: {
                url: function (data) {
                    return baseUrl + "(" + data.ProductID + ")";
                },
                dataType: "json"
            }
        },
        batch: false,
        serverPaging: true,
        serverSorting: true,
        serverFiltering: true,
        pageSize: 10,
        schema: {
            data: function (data) {
                return data.value;
            },
            total: function (data) {
                return data["odata.count"];
            },
            errors: function (e) {
                return e.errors;
            },
            model: Product
        },
        error: function (e) {
            var responseJson = e.xhr.responseJSON;
            if (responseJson != undefined) {
                if (responseJson["odata.error"] != undefined) {
                    var error = responseJson["odata.error"];
                    var message = error.message.value + '\n\n' + error.innererror.message;
                    alert(message);
                }
            } else {
                alert(e.xhr.status + "\n\n" + e.xhr.responseText + "\n\n" + e.xhr.statusText);
            }
            this.read();
        }
    });

    var viewModel = kendo.observable({
        dataSource: dataSource,
        dataBound: function (arg) {
            if (lastSelectedDataItem == null) return; // check if there was a row that was selected
            var view = this.dataSource.view(); // get all the rows
            for (var i = 0; i < view.length; i++) { // iterate through rows
                if (view[i].ProductID == lastSelectedDataItem.ProductID) { // find row with the lastSelectedProductd
                    var grid = arg.sender; // get the grid
                    grid.select(grid.table.find("tr[data-uid='" + view[i].uid + "']")); // set the selected row
                    break;
                }
            }
        },
        onChange: function (arg) {
            var grid = arg.sender;
            lastSelectedDataItem = grid.dataItem(grid.select());
        },
    });

    $(document).bind("viewSwtichedEvent", function (e, args) { // subscribe to the viewSwitchedEvent
        if (args.name == "list") { // check if this view was switched too
            if (args.isRemotelyLoaded) { // check if this view was loaded for the first time (remotely from server)
                kendo.bind($("#view"), viewModel); // bind the view to the model
            } else {// view already been loaded in cache
                viewModel.dataSource.read(); // refresh grid
            }
        }
    });

</script>
<style scoped>
    #productGrid .k-toolbar {
        padding: .7em;
    }

    .toolbar {
        float: right;
    }
</style>
 

10-9-2013 7-11-39 PM

Happy Coding…! :)

Live Demo: http://longle.azurewebsites.net
Download: https://genericunitofworkandrepositories.codeplex.com/

Bounded DbContext with Generic Unit of Work, Generic Repositories, Entity Framework 6 & EntLib Unity 3.0 in MVC 4

Update: 08/12/2013 – Changed InjectionConstructor parameter to: ResolvedParameter<IDbContext>(), to trigger compilation of the container when setting up the DbBounded Context and UnitOfWork(s) registrations.

Update: 08/08/2013 – Added PerRequestLifetimeManager() to the IUnitOfWork Unity Registration (binding) in UnityConfig.cs, so that the life-cycle of the UnitOfWork(s) instances being injected have singleton behavior within the scope of an Http request.

Update: 08/07/2013 – Ken from Microsoft has been kind enough to reach out and inform those of us that are using EF4 or EF5, that there maybe some potential collision issues, if there are entities with overlapping names, even if they live in different assemblies, please read below for a potential solution for this. If this does not apply to your use case or scenario, please continue on to the blog post after the block-quote.

At the risk of spamming your blog in comments I am turning to email. This is Ken the poster on your blog. J Your BoundedContext implementation has another interesting usage to easily support multiple DbContexts. Something that isn’t always that easy to do with a Repo + UoW frameworks. However, with EF5 and probably EF4 your readers will run into a bug if they have entities with overlapping names – EVEN IF they are separated by namespaces or live in different assemblies. For instance say you have two databases that both have a Logging table.

ExceptionMessage: The mapping of CLR type to EDM type is ambiguous because multiple CLR types match the EDM type ‘MyType’. Previously found CLR type ‘Namespace1.MyTable’, newly found CLR type ‘Namespace2.MyTable’. The mapping of CLR type to EDM type is ambiguous because multiple CLR types match the EDM type ‘ReferenceTable’. Previously found CLR type ‘Namespace1.ReferenceTable’, newly found CLR type ‘Namespace2.ReferenceTable’.”

The issue occurs with at EF5 unsure about EF4 but I suspect so. Read more here: http://entityframework.codeplex.com/workitem/911

The issue is resolved in EF6 beta1 from my testing.

Codewise this would be setup as follows

 

UnityConfig.cs
 
container.RegisterType("DbContext1");
container.RegisterType("DbContext2");
container.RegisterType(
    "DbContext1UnitOfWork", new InjectionConstructor(container.Resolve("DbContext1")));
container.RegisterType(
    "DbContext2UnitOfWork", new InjectionConstructor(container.Resolve("DbContext2")));
 
An Api Controller
 
public class SomethingFromDbContext1Controller : ApiController
    {
        private readonly IUnitOfWork _uow;
 
        public GenericRaptorTicketController(
            [Dependency("DbContext1UnitOfWork ")] IUnitOfWork uow)
        {
            _uow = uow;
        }

Now all of the above logic in the controller goes to Database1 using the types specified by namespace (dealing with overlapping table names that resulted in POCO classes that had the same name, different namespace). Easily I could add a second, third, fourth controller and specify DbContext2UnitOfWork and point to a second database. Cool stuff. Your approach is creative and I am sharing it with my peers and customers.

Now if only I have find a T4 template to bend to my will to shape the Data Mappings and Entities. Simon Huge’s Reverse POCO template comes close with a few modifications. J

-Ken

So there was an interesting question that was raised over the weekend from Tim, on could we take our generic Unit of Work and Repositories and implement the Bounded DbContext Pattern or philosophy if you will from DDD (Domain Driven Design) concepts. There are a few reasons to go with this Pattern e.g organization, manageability, decoupling, performance (in some cases), maintainability, etc.

My favorite reason is when working with large databases and having functionality in your application that is only working with specific domain areas, why load up a DbContext that has the overhead of your entire entity graph when your only working with a specific few? For example, you may have a database that has close to 100 tables (e.g. AdventureWorks), however if a user is only managing Products on a screen, why load up a DbContext that has the overhead of the entire entity graph. Figuring out where to decouple and decompose your domain model, to implement the Bounded DbContext Pattern can span a wide array of reasons, those reasons could span from business to technical reasons, usually both.

As an example, the AdventureWorks database is already separated into domain SQL Schemas, each of the tables shown here are prefixed with the SQL Schema. This is somewhat of an example of which entities would be in a Bounded DbContext, a Bounded DbContext could be created for each of the SQL Schema’s, and each of the Bounded DbContext’s would have the tables as DbSet’s in them. Again, separating your domain into areas really depends on your use cases both business and technical, this is just an example of a starting point.

7-31-2013 2-52-45 PM

Example: Potential Bounded DbContext’s in AdventureWorks based on SQL schemas defined.

  • HumanDbcontext
  • PersonDbcontext
  • ProductionDbcontext
  • PurchasingDbcontext
  • SalesDbcontext

Anyhow, back to the topic at hand, with some minor changes, here’s how we can accomplish Bounded DbContext with our UnitOfWork and Generic Repositories, we’ll start off from our last post: Generically Implementing the Unit of Work & Repository Pattern with Entity Framework in MVC & Simplifying Entity Graphs. We are using the Northwind database as an example since this was used in the previous post, however with a database schema of this size, it’s probably not the ideal candidate for Bounded DbContext, you would probably implement this pattern on a database that had a much larger schema. But for the objective of this blog, Northwind will do. :)

Note: although we are using EF6 (alpha) in this example, we aren’t using any of EF6’s new features, however, it was a bit of a wiggle to get everything working. If you are attempting to get MVC, EF6 & SQL Sever CE 4.0 working, than this post and download maybe of use.

Data.NorthwindContext.cs – Before


    public class NorthwindContext : DbContext, IDbContext
    {
        static NorthwindContext()
        {
            Database.SetInitializer<NorthwindContext>(null);
        }

        public NorthwindContext()
            : base("Name=NorthwindContext")
        {
            Configuration.LazyLoadingEnabled = false;
        }

        public new IDbSet<T> Set<T>() where T : class
        {
            return base.Set<T>();
        }

        public override int SaveChanges()
        {
            this.ApplyStateChanges();
            return base.SaveChanges();
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new CategoryMap());
            modelBuilder.Configurations.Add(new CustomerDemographicMap());
            modelBuilder.Configurations.Add(new CustomerMap());
            modelBuilder.Configurations.Add(new EmployeeMap());
            modelBuilder.Configurations.Add(new Order_DetailMap());
            modelBuilder.Configurations.Add(new OrderMap());
            modelBuilder.Configurations.Add(new ProductMap());
            modelBuilder.Configurations.Add(new RegionMap());
            modelBuilder.Configurations.Add(new ShipperMap());
            modelBuilder.Configurations.Add(new SupplierMap());
            modelBuilder.Configurations.Add(new TerritoryMap());
            modelBuilder.Configurations.Add(new InvoiceMap());
        }
    }

After

Data.DbContextBase.cs

We’ll go ahead abstract out our DbContext into a base class, since we’ll have multiple Bounded DbContexts.


    public abstract DbContextBase : DbContext, IDbContext
    {
        public DbContextBase(string nameOrConnectionString) : 
            base(nameOrConnectionString)
        {
            Configuration.LazyLoadingEnabled = false;
        }

        public new IDbSet<T> Set<T>() where T : class
        {
            return base.Set<T>();
        }

        public override int SaveChanges()
        {
            this.ApplyStateChanges();
            return base.SaveChanges();
        }
    }

Data.NorthwindCustomerDataContext.cs
*Customer Bounded Context


    public class NorthwindCustomerContext : DbContextBase
    {
        static NorthwindCustomerContext()
        {
            Database.SetInitializer<NorthwindCustomerContext>(null);
        }

        public NorthwindCustomerContext()
            : base("Name=NorthwindContext")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new CustomerDemographicMap());
            modelBuilder.Configurations.Add(new CustomerMap());
        }
    }

Data.NorthwindDataContext – Everything else, Bounded Context :p


    public class NorthwindContext : DbContextBase
    {
        static NorthwindContext()
        {
            Database.SetInitializer<NorthwindCustomerContext>(null);
        }

        public NorthwindContext()
            : base("Name=NorthwindContext")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new CategoryMap());
            modelBuilder.Configurations.Add(new EmployeeMap());
            modelBuilder.Configurations.Add(new Order_DetailMap());
            modelBuilder.Configurations.Add(new OrderMap());
            modelBuilder.Configurations.Add(new ProductMap());
            modelBuilder.Configurations.Add(new RegionMap());
            modelBuilder.Configurations.Add(new ShipperMap());
            modelBuilder.Configurations.Add(new SupplierMap());
            modelBuilder.Configurations.Add(new TerritoryMap());
            modelBuilder.Configurations.Add(new InvoiceMap());
        }
    }

We’ll need the following EntLib Unity v3.0 NuGet Packages.

  • Unity v3.0
  • Unity bootstrapper for ASP.NET MVC v3.0
  • Unity bootstrapper for ASP.NET MVC Web API v3.0

7-30-2013 9-29-07 AM

Spa.App_Start.UnityConfig.csUnity Bindings Before


container.RegisterType<IDbContext, NorthwindContext>();
container.RegisterType<IUnitOfWork, UnitOfWork>();
 

Spa.App_Start.UnityConfig.cs – Unity Bindings After (with Registration Names)


        public static void RegisterTypes(IUnityContainer container)
        {
            container.RegisterType<IDbContext, NorthwindContext>(new PerRequestLifetimeManager(), "NorthwindContext");
            container.RegisterType<IDbContext, NorthwindCustomerContext>(new PerRequestLifetimeManager(), "NorthwindCustomerContext");
            
            container.RegisterType<IUnitOfWork, UnitOfWork>(
                "NorthwindUnitOfWork", new InjectionConstructor(new ResolvedParameter<IDbContext>("NorthwindContext")));
            
            container.RegisterType<IUnitOfWork, UnitOfWork>(
                "NorthwindCustomerUnitOfWork", new InjectionConstructor(new ResolvedParameter<IDbContext>("NorthwindCustomerContext")));
        }
 

When working with ASP.NET (web apps) remember to make sure you are making good use of the UnityPerRequestHttpModule (line 12, below) in your UnityWebActivator. This will default the lifetime of your instances to lifetime of the current HttpRequest. You can configure registrations and pass in a other specific lifetime manager’s for other registration configurations who’s life-cycle does not need to bound to the HttpRequest.

Spa.App_Start.UnityWebActivator.cs


    public static class UnityWebActivator
    {
        public static void Start() 
        {
            var container = UnityConfig.GetConfiguredContainer();

            FilterProviders.Providers.Remove(FilterProviders.Providers.OfType<FilterAttributeFilterProvider>().First());
            FilterProviders.Providers.Add(new UnityFilterAttributeFilterProvider(container));

            DependencyResolver.SetResolver(new UnityDependencyResolver(container));

             DynamicModuleUtility.RegisterModule(typeof(UnityPerRequestHttpModule));
        }
    }
  

Now we could just instantiate and pass in the appropriate Bounded DbContext implementations into the UnitOfWork registrations, however we would defeat one of the fundamental reasons of DI & IoC to begin with e.g. when we write our unit test later, we aren’t going to be able to switch out DbContext with a mocked one, easily. We could even do this registration in the web.config to give us more flexibility in terms of swapping the implementations of our DbContext’s however for the purposes of this post, we’ll continue on pro-grammatically.

Spa.Controllers.CustomerController – Before

Well now, that we have Bounded DbContext and UnitOfworks, how do we get them? We have two options, first options which is leveraging DI & IoC with Unity 3.0, and the obvious method of instantiating them manually. We’ll demonstrate the first option below, in our CustomerController.


    public class CustomerController : Controller
    {
        private readonly IUnitOfWork _unitOfWork;

        public CustomerController(IUnitOfWork unitOfWork)
        {
            _unitOfWork = unitOfWork;
        }

        public ActionResult Index(int? page)
        {
            var pageNumber = page ?? 1;
            const int pageSize = 20;

            int totalCustomerCount;

            var customers =
                _unitOfWork.Repository<Customer>()
                    .Query()
                    .OrderBy(q => q
                        .OrderBy(c => c.ContactName)
                        .ThenBy(c => c.CompanyName))
                    .Filter(q => q.ContactName != null)
                    .GetPage(pageNumber, pageSize, out totalCustomerCount);

            ViewBag.Customers = new StaticPagedList<Customer>(
                customers, pageNumber, pageSize, totalCustomerCount);

            return View();
        }

        [HttpGet]
        public ActionResult Edit(string id)
        {
            var customer = _unitOfWork.Repository<Customer>().FindById(id);
            return View(customer);
        }

        [HttpPost]
        public ActionResult Edit(Customer customer)
        {
            if (ModelState.IsValid)
                RedirectToAction("Edit");

            customer.State = ObjectState.Modified;
            _unitOfWork.Repository<Customer>().Update(customer);
            _unitOfWork.Save();

            return View(customer);
        }
    }

Spa.CustomerController – After

We can get them by passing the registration name of Unity binding we setup earlier.

Option A:


    public class CustomerController : Controller
    {
        private readonly IUnitOfWork _customerUnitOfWork;
        private readonly IUnitOfWork _northwindUnitOfWork;

        public CustomerController(IUnityContainer container)
        {
            _northwindUnitOfWork = container.Resolve<IUnitOfWork>("NorthwindUnitOfWork");;
            _customerUnitOfWork = container.Resolve<IUnitOfWork>("NorthwindCustomerUnitOfWork");
        }

        public ActionResult Index(int? page)
        {
            var pageNumber = page ?? 1;
            const int pageSize = 20;

            int totalCustomerCount;

            var customers =
                _customerUnitOfWork.Repository<Customer>()
                    .Query()
                    .OrderBy(q => q
                        .OrderBy(c => c.ContactName)
                        .ThenBy(c => c.CompanyName))
                    .Filter(q => q.ContactName != null)
                    .GetPage(pageNumber, pageSize, out totalCustomerCount);

            ViewBag.Customers = new StaticPagedList<Customer>(
                customers, pageNumber, pageSize, totalCustomerCount);

            return View();
        }

        [HttpGet]
        public ActionResult Edit(string id)
        {
            var customer = _customerUnitOfWork.Repository<Customer>().FindById(id);
            return View(customer);
        }

        [HttpPost]
        public ActionResult Edit(Customer customer)
        {
            if (ModelState.IsValid)
                RedirectToAction("Edit");

            customer.State = ObjectState.Modified;
            _customerUnitOfWork.Repository<Customer>().Update(customer);
            _customerUnitOfWork.Save();

            return View(customer);
        }
    }

Option B:


    public class CustomerController : Controller
    {
        private readonly IUnitOfWork _customerUnitOfWork;
        private readonly IUnitOfWork _northwindUnitOfWork;

        public CustomerController(
            [Dependency("NorthwindUnitOfWork")] IUnitOfWork northwindUnitOfWork,
            [Dependency("NorthwindCustomerUnitOfWork")] IUnitOfWork customerUnitOfWork)
        {
            _northwindUnitOfWork = northwindUnitOfWork;
            _customerUnitOfWork = customerUnitOfWork;
        }

        public ActionResult Index(int? page)
        {
            var pageNumber = page ?? 1;
            const int pageSize = 20;

            int totalCustomerCount;

            var customers =
                _customerUnitOfWork.Repository<Customer>()
                    .Query()
                    .OrderBy(q => q
                        .OrderBy(c => c.ContactName)
                        .ThenBy(c => c.CompanyName))
                    .Filter(q => q.ContactName != null)
                    .GetPage(pageNumber, pageSize, out totalCustomerCount);

            ViewBag.Customers = new StaticPagedList<Customer>(
                customers, pageNumber, pageSize, totalCustomerCount);

            return View();
        }

        [HttpGet]
        public ActionResult Edit(string id)
        {
            var customer = _customerUnitOfWork.Repository<Customer>().FindById(id);
            return View(customer);
        }

        [HttpPost]
        public ActionResult Edit(Customer customer)
        {
            if (ModelState.IsValid)
                RedirectToAction("Edit");

            customer.State = ObjectState.Modified;
            _customerUnitOfWork.Repository<Customer>().Update(customer);
            _customerUnitOfWork.Save();

            return View(customer);
        }
    }

Note: Probably a good idea, specially in this case to go ahead and create an Enum or a class with constants instead of passing in hand coded strings as the registration name.

I prefer Option B, personally I don’t like the fact that you injecting anything with the entire Container, I rather have it when something is requesting to be injected, that the requester is specific in what it requesting for. Anyhow, I’ve seen this debate go both ways, moving on…

The alternative for those of us that are not using any IoC & DI

You should be using some form of DI & IoC with the N-number of frameworks out there, however if your not, obviously you an instantiate your Bounded UnitOfwork and DbContext directly.

Spa.CustomerController – without IoC and/or DI


    public class CustomerController : Controller
    {
        private readonly IUnitOfWork _customerUnitOfWork;
        private readonly IUnitOfWork _northwindUnitOfWork;

        public CustomerController(IUnityContainer container)
        {
            _northwindUnitOfWork = new UnitOfWork(new NorthwindContext());
            _customerUnitOfWork = new UnitOfWork(new NorthwindCustomerContext());
        }

        public ActionResult Index(int? page)
        {
            var pageNumber = page ?? 1;
            const int pageSize = 20;

            int totalCustomerCount;

            var customers =
                _customerUnitOfWork.Repository<Customer>()
                    .Query()
                    .OrderBy(q => q
                        .OrderBy(c => c.ContactName)
                        .ThenBy(c => c.CompanyName))
                    .Filter(q => q.ContactName != null)
                    .GetPage(pageNumber, pageSize, out totalCustomerCount);

            ViewBag.Customers = new StaticPagedList<Customer>(
                customers, pageNumber, pageSize, totalCustomerCount);

            return View();
        }

        [HttpGet]
        public ActionResult Edit(string id)
        {
            var customer = _customerUnitOfWork.Repository<Customer>().FindById(id);
            return View(customer);
        }

        [HttpPost]
        public ActionResult Edit(Customer customer)
        {
            if (ModelState.IsValid)
                RedirectToAction("Edit");

            customer.State = ObjectState.Modified;
            _customerUnitOfWork.Repository<Customer>().Update(customer);
            _customerUnitOfWork.Save();

            return View(customer);
        }
    }
 

Now, let’s run the application.

http://localhost:29622/Customer

7-30-2013 12-35-41 AM

There you have it, Happy Coding…! :)

Download sample application: https://skydrive.live.com/redir?resid=949A1C97C2A17906!5962

Note: Please “Enable NuGet Package Restore” on the VS Solution.

Building an Extensible Fluent Validation Framework using Generic Funcs and Wiring it up to MVC 4 with ModelValidatorProvider and ModelValidator

Live demo http://longle.azurewebsites.net/customer, courtesy of Windows Azure free 10 Websites, will keep this out there for as long as it’s free :)

We will start off in a pre-baked solution from my last post http://blog.longle.net/2013/05/17/generically-implementing-the-unit-of-work-repository-pattern-with-entity-framework-in-mvc-simplifying-entity-graphs-part-2-mvc-4-di-ioc-with-mef-attributeless-conventions/ using Unity 3.0 as our DI framework of choice.

Before we starts let’s define some of key architecture & design principles we are attempting to achieve here.

  • Validation Framework can run in any .NET technology space e.g. WPF, MVC, ASP.NET WebForms, ASP.NET MVC, SilverLight, WF, Windows Services, WCF, etc..
  • Validation Framework is extensible, and easy to do so.
  • Validation Framework will support reusable validations so that we can reuse them across the enterprise.
  • Validation Framework will support ad-hoc validations, meaning validations, that potentially will only be used once, that are not common validations, and very specific to a given entity with a unique use case.
  • Validation Framework can easily be plugged in e.g such as the MVC 4 run-time, not requiring developer’s to do anything different than they are today to validate their models.

We have a lot to cover so let’s dive right into the Validation project and its’ code!

Validation.Validator.cs


namespace Validation
{
    public class Validator<TModel> : IValidator
    {
        private readonly List<ValidationResult> _validationResults;
        private readonly List<Validation<TModel>> _validations;

        public Validator()
        {
            _validations = new List<Validation<TModel>>();
            _validationResults = new List<ValidationResult>();
        }

        public List<ValidationResult> Validate(object model)
        {
            foreach (var validation in _validations)
            {
                validation.OnValidating();
                var validater = validation.GetValidater();

                if (!validater((TModel) model))
                    _validationResults.Add(validation.GetValidationResult());
            }

            return _validationResults;
        }

        public Validation<TModel> AddValidation(Validation<TModel> validationRule)
        {
            _validations.Add(validationRule);
            return validationRule;
        }
    }
}

This is probably one of the most important class of our Validation Framework, it primary responsibility are:

  • Iterating through all of our validations for a given entity
  • Storing the result for each of the validations

Validation.Validation.cs


    public class Validation<TModel>
    {
        private string _errorMessage;
        private string _propertyName;
        private Func<TModel, bool> _validater;
        private Expression<Func<TModel, object>> _property;

        public Expression<Func<TModel, object>> GetProperty()
        {
            return _property;
        }

        public Validation<TModel> SetProperty(Expression<Func<TModel, object>> property)
        {
            _property = property;
            return this;
        }

        public string GetPropertyName()
        {
            var memberExpression = GetProperty().Body as MemberExpression ?? ((UnaryExpression) GetProperty().Body).Operand as MemberExpression;

            if (memberExpression == null)
            {
                _propertyName = default(string);
                return _propertyName;
            }

            _propertyName = memberExpression.Member.Name;

            return _propertyName;
        }

        public Validation<TModel> SetErrorMessage(string errorMessage)
        {
            _errorMessage = errorMessage;
            return this;
        }

        public Validation<TModel> SetValidater(Func<TModel, bool> validater)
        {
            _validater = validater;
            return this;
        }

        public Func<TModel, bool> GetValidater()
        {
            return _validater;
        }

        public string GetErrorMessage()
        {
            return _errorMessage;
        }

        public ValidationResult GetValidationResult()
        {
            return new ValidationResult {ErrorMessage = GetErrorMessage(), PropertyName = GetPropertyName()};
        }

        public virtual void OnValidating()
        {
            if (string.IsNullOrEmpty(_errorMessage))
                _errorMessage = GetPropertyName() + " is not valid";
        }}

The Validation class is primarily responsible for:

  • Keeping track which property of the entity it’s its validation is for.
  • Setting the appropriate validation result and message.

Now really this is really all you need to start validating your entities/models. Although, there are some other classes that are in the Validation project, they are really not needed to start validating. They are there to help us later wire up our Validation Framework to MVC 4. With that being said let’s wire up our first validation, all you need to do is implement the the Validator class.

I’ve added a UnitTest project with two test class, one is simply a dummy model with fictitious property names, the property names are named after the type of validation we are performing on the property so that we can easily understand what type of validation is happening on each of them. The second class MyValidator is where are validations actually reside for validating MyModel.cs.

Notice all the validations are stored in the MyValidator.cs class and that our MyModel.cs knows nothing about any validation business. More importantly our validation is completely decoupled from our entities, giving us nice separation of concerns.

Validation.Tests.MyModel.cs

Note: Again, The property names here are named so that we can easily see what types of validations are happening for each of them. Obviously in the real world they would be named FirstName, LastName, Age, versus Compare1, Compare2, Regex, etc. :p


namespace Validation.Test
{
    public class MyModel
    {
        public string Compare1 { get; set; }
        public string Compare2 { get; set; }
        public string CreditCard { get; set; }
        public string Id { get; set; }
        public string Length { get; set; }
        public string Range { get; set; }
        public string Regex { get; set; }
        public string Required { get; set; }
        public string IpAddress { get; set; }
        public string Email { get; set; }
    }
}

Validation.Tests.MyValidator.cs
A simple test/sample validator implementation so that we can code up a quick unit test.


namespace Validation.Test
{
    public class MyValidator : Validator<MyModel>
    {
        public MyValidator()
        {
            this.ValidateCompare(m => m.Compare1, m => m.Compare2)
                .WithDataType(ValidationDataType.Integer)
                .WithOperator(ValidationOperator.GreaterThan);

            this.ValidateCreditCard(m => m.CreditCard);

            this.ValidateId(m => m.Id);

            this.ValidateLength(m => m.Length)
                .WithMax(5)
                .WithMin(1);

            this.ValidateRange(m => m.Range)
                .WithDataType(ValidationDataType.Integer)
                .WithMin(1)
                .WithMax(5);

            this.ValidateRegex(m => m.Regex)
                .SetPattern(@"\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*")
                .SetErrorMessage("Email must be in valid format");

            this.ValidateRequired(m => m.Required);

            this.ValidateIpAddress(m => m.IpAddress);

            this.ValidateEmail(m => m.Email);

            this.AddValidation()
                .SetProperty(m => m.Email)
                .SetValidater(model => !string.IsNullOrEmpty(model.Email))
                .SetErrorMessage("Email is required");
        }
    }
}

Here we have some simple validation implemented and wired up for our MyModel.cs entity. Here we are using some of the out of the box validations I’ve coded up, and some ad-hoc validations we are able to add to our Validator that the Validation Framework provides e.g. validating and Id, length, range, using Regex, required, IP address, email, etc.. Obviously you can easily add your own reusable validation, and again add ad-hoc (lines 34-37) validations that will probably only be specific to a given entity.

Now let’s test our validation by coding up a quick unit test.

ValidationTests.UnitTest1.cs


namespace Validation.Test
{
    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod1()
        {
            var myModel = new MyModel();
            var myValidator = new MyValidator();
            var validationResults = myValidator.Validate(myModel);
            
            Assert.AreEqual(validationResults.Count, 4);
            Assert.AreEqual(validationResults[0].PropertyName, "Compare1" );
            Assert.AreEqual(validationResults[1].PropertyName, "Id");
            Assert.AreEqual(validationResults[2].PropertyName, "Required");
            Assert.AreEqual(validationResults[3].PropertyName, "Email");
        }
    }
}

If we run our unit test, we can see that MyModel.cs was nicely validated…!

6-3-2013 2-41-04 PM

Now, this is great, but how do we seamlessly wire this up to MVC 4..?! Good question, let’s get started. To wire up our new Validation Framework with the MVC 4 run-time there are a couple of things we need to do.

First is to implement the ModelValidatorProvider (http://msdn.microsoft.com/en-us/library/system.web.mvc.modelvalidatorprovider(v=vs.98).aspx), this will provide the MVC 4 runtime the necessary implementation to get a set of validations for a model.

Validation.CustomModelValidatorProvider.cs


namespace Validation
{
    public class CustomModelValidatorProvider : ModelValidatorProvider
    {
        public override IEnumerable<ModelValidator> GetValidators(ModelMetadata metadata, ControllerContext context)
        {
            var isPropertyValidation = metadata.ContainerType != null && !String.IsNullOrEmpty(metadata.PropertyName);

            if (isPropertyValidation) yield break;

            var validatorFactory = new ValidatorFactory();
            var validator = validatorFactory.GetValidator(metadata.ModelType, metadata.Model);

            if (validator != null)
                yield return new CustomModelValidator(metadata, context, validator);
        }
    }
}

When implementing the ModeValidatorProvider we see that we do need a factory of some sort to new up an instance of the right Validator to validate our model. We accomplish this with the ValidatorFactory. This class is responsible for discovering the ValidatorAttribute that the MVC model should be decorated with has the Validator type to be activated to validate the model.

Validation.ValidatorFactory.cs


namespace Validation
{
    public class ValidatorFactory
    {
        public IValidator GetValidator(Type type, object model)
        {
            var validatorAttributes = type.GetCustomAttributes(typeof (ValidatorAttribute), true);

            if (validatorAttributes.Length > 0)
            {
                var validatorAttribute = (ValidatorAttribute) validatorAttributes[0];
                return Activator.CreateInstance(validatorAttribute.Validator) as IValidator;
            }   
            return null;
        }
    }
}

The ValidatorAttribute is pretty straight forward, it’s an attribute that accepts a type, which is the Validator type we need to activate to validate the model.

Validation.ValidatorAttribute.cs


namespace Validation
{
    [AttributeUsage(AttributeTargets.Class)]
    public class ValidatorAttribute : Attribute
    {
        private readonly Type _validator;

        public ValidatorAttribute(Type validator)
        {
            _validator = validator;
        }


        public Type Validator
        {
            get { return _validator; }
        }
    }
}

Let’s take a look at our Customer model that is decorated with the ValidatorAttribute so that our ValidatorFactory knows which Validator to activate for it, in our case CustomerValidator.cs.

Data.Models.Customer.cs


namespace Data.Models
{
    [Validator(typeof (CustomerValidator))]
    public class Customer : IObjectState
    {
        public Customer()
        {
            Orders = new List<Order>();
            CustomerDemographics = new List<CustomerDemographic>();
        }

        public string CustomerID { get; set; }
        public string CompanyName { get; set; }
        public string ContactName { get; set; }
        public string ContactTitle { get; set; }
        public string Address { get; set; }
        public string City { get; set; }
        public string Region { get; set; }
        public string PostalCode { get; set; }
        public string Country { get; set; }
        public string Phone { get; set; }
        public string Fax { get; set; }
        public virtual ICollection<Order> Orders { get; set; }
        public virtual ICollection<CustomerDemographic> CustomerDemographics { get; set; }
        public ObjectState State { get; set; }
    }
}

Second, we need to implement the ModelValidator (http://msdn.microsoft.com/en-us/library/system.web.mvc.modelvalidator(v=vs.108).aspx), this will provide the MVC 4 runtime to call into our Validation Framework and execute our Validator.Validate(object model) method and return a set of ValidationResults. Once our ValidationResult payload is returned we will then need to map it back to MVC’s ModelValidationResult so that it can display our validation messages correctly.

Validation.CustomModelValidator.cs


namespace Validation
{
    public class CustomModelValidator : ModelValidator
    {
        private readonly IValidator _validator;

        public CustomModelValidator(ModelMetadata metadata, ControllerContext controllerContext, IValidator validator)
            : base(metadata, controllerContext)
        {
            _validator = validator;
        }

        public override IEnumerable<ModelValidationResult> Validate(object container)
        {
            var validationResults = _validator.Validate(Metadata.Model);

            return validationResults
                .Select(validationResult => 
                    new ModelValidationResult
                        {
                            MemberName = validationResult.PropertyName, 
                            Message = validationResult.ErrorMessage
                        });
        }
    }
}

Finally we need to register our Validation.CustomModelValidatorProvider.cs implementation with the MVC runtime.

Web.Global.asax.cs


namespace Web
{
    // Note: For instructions on enabling IIS6 or IIS7 classic mode, 
    // visit http://go.microsoft.com/?LinkId=9394801

    public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            Bootstrapper.Initialise();

            AreaRegistration.RegisterAllAreas();

            WebApiConfig.Register(GlobalConfiguration.Configuration);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
            AuthConfig.RegisterAuth();

            // Add our custom ModelValiidatorProvider for MVC runtime
            ModelValidatorProviders.Providers.Add(new CustomModelValidatorProvider());
        }
    }
}

Now let’s start off by validating one of our existing entities Entites.Customer.cs. You can really place your validation objects anywhere you’d like, for simplicity sake I’ll go ahead and place them in the same project as our Entities under a folder named Validations.

Entities.Validators.CustomerValidator.cs


namespace Entities.Validations
{
    internal class CustomerValidator : Validator<Customer>
    {
        public CustomerValidator()
        {
            this.ValidateId(m => m.CustomerID);

            this.ValidateLength(m => m.CompanyName)
                .WithMax(5)
                .WithMin(1);

            this.ValidateRequired(m => m.ContactName);

            this.AddValidation()
                .SetProperty(m => m.City)
                .SetValidater(model => !string.IsNullOrEmpty(model.City))
                .SetErrorMessage("Customer city is required");
        }
    }
}

Now let’s edit our existing CustomController and add two more actions for editing our Customer entity.

Web.Controllers.CustomerController.cs


namespace Web.Controllers
{
    public class CustomerController : Controller
    {
        private readonly IUnitOfWork _unitOfWork;

        public CustomerController(IUnitOfWork unitOfWork)
        {
            _unitOfWork = unitOfWork;
        }

        public ActionResult Index(int? page)
        {
            var pageNumber = page ?? 1;
            const int pageSize = 20;

            int totalCustomerCount;

            var customers =
                _unitOfWork.Repository<Customer>()
                    .Query()
                    .Include(i => i.Orders)
                    .OrderBy(q => q
                        .OrderBy(c => c.ContactName)
                        .ThenBy(c => c.CompanyName))
                    .Filter(q => q.ContactName != null)
                    .GetPage(pageNumber, pageSize, out totalCustomerCount);

            ViewBag.Customers = new StaticPagedList<Customer>(
                customers, pageNumber, pageSize, totalCustomerCount);

            return View();
        }

        [HttpGet]
        public ActionResult Edit(string id)
        {
            var customer = _unitOfWork.Repository<Customer>().FindById(id);
            return View(customer);
        }

        [HttpPost]
        public ActionResult Edit(Customer customer)
        {
            if (ModelState.IsValid)
                RedirectToAction("Edit");
            
            _unitOfWork.Repository<Customer>().Update(customer);
            _unitOfWork.Save();

            return View(customer);
        }
    }
}

Notice how we are calling the MVC ModelState.IsValid, and when we debugging this, we see that the MVC run-time will invoke our custom Validation Framework.

6-3-2013 3-30-50 PM

Our error message from Entities.Validation.CustomerValidator.cs.

6-3-2013 3-31-57 PM

All of the out of the box Validators that are included in the example download, follow the described pattern listed below, this is also how you would extend or add your own reusable validations to the framework.

  1. Extend the Validator, by writing an Extension method
  2. Instantiating a fluent helper class for the validation
  3. Setting the property to be validated
  4. Setting the validation logic
  5. Adding the the validation to stack of validations to the Validator instance

Let’s take a quick look at one of the out of the box validations e.g. ValidateLength.

Validation.Validators.ValidateLengthExtension.cs


namespace Validation.Validators
{
    public static class ValidateLengthExtension
    {
        public static ValidateLengthFluentHelper<TModel> ValidateLength<TModel>(this Validator<TModel> validator, Expression<Func<TModel, object>> property)
        {
            var fluentHelper = new ValidateLengthFluentHelper<TModel>();

            fluentHelper.SetProperty(property);
            fluentHelper.SetValidater(model =>
                {
                    var value = property.GetPropertyValue(model) as string;

                    return string.IsNullOrEmpty(value) || value.Length >= fluentHelper.GetMin() && value.Length <= fluentHelper.GetMax();
                });

            validator.AddValidation(fluentHelper);

            return fluentHelper;
        }
    }
}

To provide a nice and easy to use fluent API experience, let’s take a look at the fluent helper class for this validation.

Validation.Validators.ValidateLengthFluentHelper.cs


namespace Validation.Validators
{
    public class ValidateLengthFluentHelper<TModel> : Validation<TModel>
    {
        private int _max;
        private int _min;

        public override void OnValidating()
        {
            if (String.IsNullOrEmpty(GetErrorMessage()))
                SetErrorMessage(GetPropertyName() + " must be between " + _min + " and " + _max + " characters long.");
        }

        public int GetMin()
        {
            return _min;
        }

        public int GetMax()
        {
            return _max;
        }

        public new ValidateLengthFluentHelper<TModel> SetProperty(Expression<Func<TModel, object>> propertySelector)
        {
            base.SetProperty(propertySelector);
            return this;
        }

        public ValidateLengthFluentHelper<TModel> WithMin(int min)
        {
            _min = min;
            return this;
        }

        public ValidateLengthFluentHelper<TModel> WithMax(int max)
        {
            _max = max;
            return this;
        }
    }
}

To use this is fairly straight forward and simple..!

ValidationTest.MyValidator.cs


            this.ValidateLength(m => m.Length)
                .WithMax(5)
                .WithMin(1);


Support for Ad-Hoc Validations with Generic Funcs using AddValidation() Fluent Method

Finally, let’s quickly go over adding ad-hoc validations by adding in-line Lambda’s or Generic Funcs, all you hvae to do is call AddValidation() and using the fluent API, and make sure your generic func accepts a TModel (could be of any object type) and returns a Boolean. In the sample code below we are doing a simple ad-hoc validation for the property Email, validating if there’s a value or not and returning an validation message.

ValidationTest.MyValidator.cs


            this.AddValidation()
                .SetProperty(m => m.Email)
                .SetValidater(model => !string.IsNullOrEmpty(model.Email))
                .SetErrorMessage("Email is required");


There you have it, a Validation Framework registered and wired up to the MVC 4 run-time.

Happy Coding..! :)

Download sample application.

https://skydrive.live.com/redir?resid=949A1C97C2A17906!5153&authkey=!AKbcAGKuETlcm6M

Generically Implementing the Unit of Work & Repository Pattern with Entity Framework in MVC & Simplifying Entity Graphs

Update: 02/24/2014 – v3.2 released, improved API and reusable queries with the variation of the Query Object Pattern. Breaking change: Framework now ships returning all things TEntity or IEnumberable for compartmentalization, you will need to change the Repository.cs (see below, what methods signatures to change) if IQueryable is preferred over IEnumerable, IEnumerable is preferred as a best practice (http://genericunitofworkandrepositories.codeplex.com/documentation).

Update [01/06/2014] Quick start online video: http://blog.longle.net/2014/01/06/unit-of-work-unity-3-quick-start-video/

1-3-2014 5-43-38 PM

Update [11/18/2013]: Added mocked DbContext and DbSet and example Unit Tests using the mocks, download: https://genericunitofworkandrepositories.codeplex.com

This will be part two of a six part series of blog posts.

  1. Modern Web Application Layered High Level Architecture with SPA, MVC, Web API, EF, Kendo UI, OData
  2. Generically Implementing the Unit of Work & Repository Pattern with Entity Framework in MVC & Simplifying Entity Graphs
  3. MVC 4, Kendo UI, SPA with Layout, View, Router & MVVM
  4. MVC 4, Web API, OData, EF, Kendo UI, Grid, Datasource (CRUD) with MVVM
  5. MVC 4, Web API, OData, EF, Kendo UI, Binding a Form to Datasource (CRUD) with MVVM
  6. Upgrading to Async with Entity Framework, MVC, OData AsyncEntitySetController, Kendo UI, Glimpse & Generic Unit of Work Repository Framework v2.0

Update: 09/18/2013 – Sample application and source code has been uploaded to CodePlex: https://genericunitofworkandrepositories.codeplex.com, updated project to VS2013, Twitter Bootstrap, MVC 5, EF6, Kendo UI Bootstrap theme, project redeployed to Windows Azure Website.

Update: 07/30/2013 – To see this implementation with DI & IoC with EntLib Unity v3.0, see post: Bounded DbContext with Generic Unit of Work, Generic Repositories, Entity Framework 6 & EntLib Unity 3.0 in MVC 4.

Update: 06/21/2013 – Bug fix: Issue with deleting objects by Id in Repository.Delete(object Id). Updated blog post, and sample solution and added live demo link.

Live demo: http://longle.azurewebsites.net

First off let’s elegantly setup our solution, and prep it for real world development. We have our solution broken up into four different projects, now let’s talk about the “why?”.

5-8-2013 9-08-17 PM

Data Project (Data Access Layer)

This is where all of our ORM tooling related objects reside. In our case the EF (Entity Framework 6.0 Alpha 3) DataContext, Mappings, Migrations, etc. This give is nice separation, control and isolation of where any persistence related objects live. If ever, one day we need to change the tool of choice, or even upgrade, there’s only one layer or project to do this in, the Data project.

5-8-2013 10-08-26 PM

Entities Project (Domain Layer)
The Entities project is where all of our POCO (Plan Old C# Objects) objects will live. POCO’s should be very ignorant objects that pretty much have nothing in them but the structure of your data. With that being said, typically anything outside our Repository layer e.g. presentation layer (MVC), services layer (will cover in next post) should be completely ignorant to any persistence tool or technology e.g. NHibernate, eXpressPersistent, OpenAccess, EF (our case), etc.

5-8-2013 10-09-31 PM

Repository (Layer)
This is where our UoW (Unit of Work) pattern will be implemented as well as our Repository implementation. Our UoW implementation will handle most of our usual CRUD activities.

Two important objectives we will try to with our UoW pattern implementation are:

  1. Abstract away the ORM tool, in our case EF.
  2. Ensuring that all interactions with the database are happening under one DbContext instance per page request.

Obviously there are many other benefits, such giving us the ability to implement different variations of our UoW, potentially wire up to different types of repositories. For purposes of this article, we’ll stake focus on our two primary objectives, and I’ll cover the other benefits in later posts.

Web Project (Presentation Layer)
This is our presentation layer, for the purposes of the blog, we will use MVC (ASP.NET MVC 4). Again, this project should not have any dependent code on EF assembly, therefore that should not be any references to the EF assembly, it should only reference our Repository project for data access.

Refactoring the NorthwindContext for an Abstracted and Cleaner Implementation

Now that we’ve gone over the solution and it’s projects, let’s do a little bit of refactoring and cleaning up with our EF code.

Data.NorthwindDataContext.cs

Before:


    public class NorthwindContext : DbContext
    {
        static NorthwindContext()
        {
            Database.SetInitializer<NorthwindContext>(null);
        }

        public NorthwindContext()
            : base("Name=NorthwindContext")
        {
        }

        public DbSet Category Categories { get; set; }
        public DbSet CustomerDemographic CustomerDemographics { get; set; }
        public DbSet Customer Customers { get; set; }
        public DbSet Employee Employees { get; set; }
        public DbSet OrderDetail Order_Details { get; set; }
        public DbSet Order Orders { get; set; }
        public DbSet Product Products { get; set; }
        public DbSet Region Regions { get; set; }
        public DbSet Shipper Shippers { get; set; }
        public DbSet Supplier Suppliers { get; set; }
        public DbSet Territory Territories { get; set; }
        public DbSet Invoice Invoices { get; set; }


        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new CategoryMap());
            modelBuilder.Configurations.Add(new CustomerDemographicMap());
            modelBuilder.Configurations.Add(new CustomerMap());
            modelBuilder.Configurations.Add(new EmployeeMap());
            modelBuilder.Configurations.Add(new Order_DetailMap());
            modelBuilder.Configurations.Add(new OrderMap());
            modelBuilder.Configurations.Add(new ProductMap());
            modelBuilder.Configurations.Add(new RegionMap());
            modelBuilder.Configurations.Add(new ShipperMap());
            modelBuilder.Configurations.Add(new SupplierMap());
            modelBuilder.Configurations.Add(new TerritoryMap());
            modelBuilder.Configurations.Add(new InvoiceMap());
        }
    }

After:

     public class NorthwindContext : DbContext, IDbContext
    {
        static NorthwindContext()
        {
            Database.SetInitializer<NorthwindContext>(null);
        }

        public NorthwindContext()
            : base("Name=NorthwindContext")
        {
        }

        public new IDbSet<T> Set<T>() where T : class
        {
            return base.Set<T>();
        }

        public override int SaveChanges()
        {
            this.ApplyStateChanges();
            return base.SaveChanges();
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new CategoryMap());
            modelBuilder.Configurations.Add(new CustomerDemographicMap());
            modelBuilder.Configurations.Add(new CustomerMap());
            modelBuilder.Configurations.Add(new EmployeeMap());
            modelBuilder.Configurations.Add(new Order_DetailMap());
            modelBuilder.Configurations.Add(new OrderMap());
            modelBuilder.Configurations.Add(new ProductMap());
            modelBuilder.Configurations.Add(new RegionMap());
            modelBuilder.Configurations.Add(new ShipperMap());
            modelBuilder.Configurations.Add(new SupplierMap());
            modelBuilder.Configurations.Add(new TerritoryMap());
            modelBuilder.Configurations.Add(new InvoiceMap());
        }
    }

We can see that our DbContext is now much cleaner, and that it implements IDbContext. IDbContext will be the abstraction we will be working with when interacting with it’s concrete implementation, NorthwindContext.

Best Practice, Coding Against Abstractions or Interfaces

Abstractions serve as a nice flexibility point later, allowing us to implement different variations of the abstraction (interface). This will be very useful later when we implement DI (Dependency Injection and IoC (Inverse of Control) patterns. Coding to an abstraction will also help us easily create unit test, allowing us to inject faked or mocked instances as well. If your a bit unclear on how this helps set stage for DI, IoC and Unit Testing, no worries, I’ll cover these topics in the next post.

Data.IDbContext.cs


namespace Data
{
    public interface IDbContext
    {
        IDbSet<T> Set<T>() where T : class;
        int SaveChanges();
        DbEntityEntry Entry(object o);
        void Dispose();
    }
}

Now, let’s take take a look at what’s all in our Repository project, where our generic extensible repositories will reside.

5-10-2013 7-02-10 PM

IUnitOfWork This is simply the contract or abstraction that we will be working with, when interacting with it’s concrete implementation which will be UnitOfWork object.

Repository.IUnitOfwork.cs



namespace Repository
{
    public interface IUnitOfWork
    {
        void Dispose();
        void Save();
        void Dispose(bool disposing);
        IRepository<T> Repository<T>() where T : class;
    }
}

Concrete Implementation of IUnitOfWork.cs


namespace Repository
{
    public class UnitOfWork : IUnitOfWork
    {
        private readonly IDbContext _context;

        private bool _disposed;
        private Hashtable _repositories;

        public UnitOfWork(IDbContext context)
        {
            _context = context;
        }

        public UnitOfWork()
        {
            _context = new NorthwindContext();
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        public void Save()
        {
            _context.SaveChanges();
        }

        public virtual void Dispose(bool disposing)
        {
            if (!_disposed)
                if (disposing)
                    _context.Dispose();

            _disposed = true;
        }

        public IRepository<T> Repository<T>() where T : class
        {
            if (_repositories == null)
                _repositories = new Hashtable();

            var type = typeof (T).Name;

            if (!_repositories.ContainsKey(type))
            {
                var repositoryType = typeof (Repository<>);

                var repositoryInstance = 
                    Activator.CreateInstance(repositoryType
                            .MakeGenericType(typeof (T)), _context);
                
                _repositories.Add(type, repositoryInstance);
            }

            return (IRepository<T>) _repositories[type];
        }
    }
}

Let’s take a look at our IRepository Repository() method here in our UnitOfWork implementation. Here we are storing all the activated instances of repositories for each and every requests. One there is a request for a given repository we will first check to see if our Hashtable (container to hold all of our activated repository instances) has been created, if not, will go ahead and create our container. Next, we’ll scan our container to see if the requested repository instance has already been created, if it has, then will return it, if it hasn’t, we will activate the requested repository instance, store it in our container, and then return it. If it helps, you can think of this as lazy loading our repository instances, meaning we are only creating repository instances on demand, this allows us to only create the repository instances needed for a given web request. Last but not least, notice here how we are following best practices mentioned earlier, we are not return the concrete implementation for the Repository, but the abstraction, IRepository.

Repository.IRepository.cs


namespace Repository
{
    public interface IRepository<TEntity> where TEntity : class
    {
        TEntity FindById(object id);
        void InsertGraph(TEntity entity);
        void Update(TEntity entity);
        void Delete(object id);
        void Delete(TEntity entity);
        void Insert(TEntity entity);
        RepositoryQuery<TEntity> Query();
    }
}


Repository.Repository.cs


    public class Repository<TEntity> : IRepository<TEntity> where TEntity : class
    {
        internal IDbContext Context;
        internal IDbSet<TEntity> DbSet;

        public Repository(IDbContext context)
        {
            Context = context;
            DbSet = context.Set<TEntity>();
        }

        public virtual TEntity FindById(object id)
        {
            return DbSet.Find(id);
        }

        public virtual void InsertGraph(TEntity entity)
        {
            DbSet.Add(entity);
        }

        public virtual void Update(TEntity entity)
        {
            DbSet.Attach(entity);
        }

        public virtual void Delete(object id)
        {
            var entity = DbSet.Find(id);
            var objectState = entity as IObjectState;
            if (objectState != null) 
                objectState.State = ObjectState.Deleted;
            Delete(entity);
        }

        public virtual void Delete(TEntity entity)
        {
            DbSet.Attach(entity);
            DbSet.Remove(entity);
        }

        public virtual void Insert(TEntity entity)
        {
            DbSet.Attach(entity);
        }

        public virtual RepositoryQuery<TEntity> Query()
        {
            var repositoryGetFluentHelper =
                new RepositoryQuery<TEntity>(this);

            return repositoryGetFluentHelper;
        }

        internal IQueryable<TEntity> Get(
            Expression<Func<TEntity, bool>> filter = null,
            Func<IQueryable<TEntity>,
                IOrderedQueryable<TEntity>> orderBy = null,
            List<Expression<Func<TEntity, object>>>
                includeProperties = null,
            int? page = null,
            int? pageSize = null)
        {
            IQueryable<TEntity> query = DbSet;
            
            if (includeProperties != null)
                includeProperties.ForEach(i => { query = query.Include(i); });

            if (filter != null)
                query = query.Where(filter);

            if (orderBy != null)
                query = orderBy(query);

            if (page != null && pageSize != null)
                query = query
                    .Skip((page.Value - 1)*pageSize.Value)
                    .Take(pageSize.Value);

            return query;
        }
    }

Our generic implementation for Repository allows us to have have all our basic heavy lifting of a Repository out of the box for any one of our Entities. All we have to do is request for the Repository of interest by passing in the Entity e.g.

UnitOfWork.Repository<Customer>

will give us the Customer Repository with all our out of the box plumbing available.

Let’s take a quick look at our Get method in the Repository implementation.


        internal IEnumerable<TEntity> Get(
            Expression<Func<TEntity, bool>> filter = null,
            Func<IQueryable<TEntity>,
                IOrderedQueryable<TEntity>> orderBy = null,
            List<Expression<Func<TEntity, object>>>
                includeProperties = null,
            int? page = null,
            int? pageSize = null)
        {
            IQueryable<TEntity> query = DbSet;
            
            if (includeProperties != null)
                includeProperties.ForEach(i => query.Include(i));

            if (filter != null)
                query = query.Where(filter);

            if (orderBy != null)
                query = orderBy(query);

            if (page != null && pageSize != null)
                query = query
                    .Skip((page.Value - 1)*pageSize.Value)
                    .Take(pageSize.Value);


            return query.ToList();
        }

The Get method here, handles fetching data. It handles querying the data supporting a filtering, ordering, paging, and eager loading of child types, so that we can make one round trip and eager load the entity graph.

We notice here that the method is marked “internal”, this is because we only want the Get method here to be accessible to objects with the same assembly, Repository.dll. We will expose the Get method via the Query method and return the RepositoryQuery object to provide a fluent “ish” api, so that’s its a bit more easy and intuitive for our developers when querying with our Repository layer. Note, only methods in our RepositoryQuery will actually invoke the internal Get method, again, which is why we went ahead and marked the Get method internal.

Repository.RepositoryQuery.cs (our fluent api helper class)


    public sealed class RepositoryQuery<TEntity> where TEntity : class
    {
        private readonly List<Expression<Func<TEntity, object>>> 
            _includeProperties;

        private readonly Repository<TEntity> _repository;
        private Expression<Func<TEntity, bool>> _filter;
        private Func<IQueryable<TEntity>, 
            IOrderedQueryable<TEntity>> _orderByQuerable;
        private int? _page;
        private int? _pageSize;

        public RepositoryQuery(Repository<TEntity> repository)
        {
            _repository = repository;
            _includeProperties = 
                new List<Expression<Func<TEntity, object>>>();
        }

        public RepositoryQuery<TEntity> Filter(
            Expression<Func<TEntity, bool>> filter)
        {
            _filter = filter;
            return this;
        }

        public RepositoryQuery<TEntity> OrderBy(
            Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy)
        {
            _orderByQuerable = orderBy;
            return this;
        }

        public RepositoryQuery<TEntity> Include(
            Expression<Func<TEntity, object>> expression)
        {
            _includeProperties.Add(expression);
            return this;
        }

        public IEnumerable<TEntity> GetPage(
            int page, int pageSize, out int totalCount)
        {
            _page = page;
            _pageSize = pageSize;
            totalCount = _repository.Get(_filter).Count();

            return _repository.Get(
                _filter, 
                _orderByQuerable, _includeProperties, _page, _pageSize);
        }

        public IEnumerable<TEntity> Get()
        {
            return _repository.Get(
                _filter, 
                _orderByQuerable, _includeProperties, _page, _pageSize);
        }
    }

Addressing IRepository<TEntity> Extensibility

Well, what happens if we need extra methods a specific Repository? Meaning, how do we address “extensiblility” in our Repository? No problem, we have a couple of options here, we can simply inherit a Repository and add your own methods to it, or what I prefer, create extension methods e.g. extending IRepository (with some pseudo code for validating an address with UPS).

Repository.CustomerRepository.cs

    /// <summary>
    /// Extending the IRepository<Customer>
    /// </summary>
    public static class CustomerRepository
    {
        public static decimal GetCustomerOrderTotalByYear(
            this IRepository<Customer> customerRepository, 
            int customerId, int year)
        {
            return customerRepository
                .FindById(customerId)
                .Orders.SelectMany(o => o.OrderDetails)
                .Select(o => o.Quantity*o.UnitPrice).Sum();
        }

    /// <summary>
    /// TODO:
    /// This should really live in the Services project (Business Layer), 
    /// however, we'll leave it here for now as an example, and migrate
    /// this in the next post.
    /// </summary>
        public static void AddCustomerWithAddressValidation(
            this IRepository<Customer> customerRepository, Customer customer)
        {
            USPSManager m = new USPSManager("YOUR_USER_ID", true);
            Address a = new Address();
            a.Address1 = customer.Address;
            a.City = customer.City;

            Address validatedAddress = m.ValidateAddress(a);

            if (validatedAddress != null)
            customerRepository.InsertGraph(customer);
        }
    }

Great, now that we have our project nicely structured with the our generic implementation of the Unit of Work and Repository Pattern, let’s see how we can leverage this by wiring up a simple controller to show a list of customers.

To help us with this go ahead and NuGet the PagedList for MVC so we easily create a view with a paged grid.

5-10-2013 6-22-37 PM

Let’s create a CustomerController Index Action load a paged list of customers to hydrate a grid.


    public class CustomerController : Controller
    {
        public ActionResult Index(int? page)
        {
            var pageNumber = page ?? 1;
            const int pageSize = 20;

            var unitOfWork = new UnitOfWork();

            int totalCustomerCount;

            var customers =
                unitOfWork.Repository<Customer>()
                    .Query()
                    .Include(i => i.CustomerDemographics)
                    .OrderBy(q => q
                        .OrderBy(c => c.ContactName)
                        .ThenBy(c => c.CompanyName))
                    .Filter(q => q.ContactName != null)
                    .GetPage(pageNumber, pageSize, out totalCustomerCount);

            ViewBag.Customers = new StaticPagedList<Customer>(
                customers, pageNumber, pageSize, totalCustomerCount);

            unitOfWork.Save();

            return View();
        }
    }

Next, let’s wire up the Index.cshtml view for our CustomerController Index Action.


@{
    ViewBag.Title = "Customers";
}

@using PagedList.Mvc;
@using PagedList;

<h2>Customers</h2>

<link href="/Content/PagedList.css" rel="stylesheet" type="text/css" />

<h2>List of Customers</h2>

<p>
    @Html.ActionLink("Create New", "Create")
</p>
<table style="width: 100%; padding: 10px;">
    <tr style="background-color: lightgray; padding: 10px;">
        <th>#</th>
        <th>Company
        </th>
        <th>Name
        </th>
        <th>Title
        </th>
        <th>Order Date
        </th>
    </tr>

    @foreach (var item in ViewBag.Customers)
    {
        <tr>
            <td>
                @Html.ActionLink(
                    "Edit", "Edit", new { id = item.CustomerID }) |

                @Html.ActionLink(
                    "Details", "Details", new { id = item.CustomerID }) |

                @Html.ActionLink(
                    "Delete", "Delete", new { id = item.CustomerID })
            </td>
            <td>
                @item.CompanyName
            </td>
            <td>
                @item.ContactName
            </td>
            <td>
                @item.ContactTitle
            </td>
            <td>
                @if (item.Orders.Count > 1)
                {
                    @item.Orders[1].OrderDate.ToShortDateString()
                }
            </td>
        </tr>
    }


    <tr>
        <td colspan="9">
            @Html.PagedListPager(
                (IPagedList)ViewBag.Customers, page => 
                    Url.Action("Index", new { page }))
        </td>
    </tr>

</table>


Go ahead and run our project to see our paged customers grid.

5-10-2013 6-46-30 PM

Abstracting the Complexity when Dealing with Entity Graphs

Another item I wanted to go over was insert and updating graphs with our Repository pattern. There are four use cases for inserting graphs, they are as follows.

5-10-2013 7-34-28 PM

To abstract the complexity and EF experience required, and how the DbContext manages graphs e.g to know to set the root entity state and how it affects other entities in the graph (e.g. updating the root entity in the graph, and existing entities in the graph are to be updated or deleted) we added a interface IOjectState that all of our entities will implement.

Entities.IObjectState.cs


namespace Data
{
    public interface IObjectState
    {
        ObjectState State { get; set; }
    }
}

Entities.ObjectState.cs (enum)


namespace Data
{
    public enum ObjectState
    {
        Unchanged,
        Added,
        Modified,
        Deleted
    }
}

These two classes will allow our development team to explicitly set the state of each of the entities in the graph when inserting or updating a graph. To make use of the classes we’ll need to extend the DbContext with a few methods, we’ll do this by creating extension methods.

Data.DbContextExtension.cs


    public static class DbContextExtension
    {
        public static void ApplyStateChanges(this DbContext dbContext)
        {
            foreach (var dbEntityEntry in dbContext.ChangeTracker.Entries())
            {
                var entityState = dbEntityEntry.Entity as IObjectState;
                if (entityState == null)
                    throw new InvalidCastException(
                        "All entites must implement " +
                        "the IObjectState interface, this interface " +
                        "must be implemented so each entites state" +
                        "can explicitely determined when updating graphs.");

                dbEntityEntry.State = ConvertState(entityState.State);
            }
        }

        private static EntityState ConvertState(ObjectState state)
        {
            switch (state)
            {
                case ObjectState.Added:
                    return EntityState.Added;
                case ObjectState.Modified:
                    return EntityState.Modified;
                case ObjectState.Deleted:
                    return EntityState.Deleted;
                default:
                    return EntityState.Unchanged;
            }
        }
    }

Now we will override the SaveChanges in our NorthwindContext to invoke the ApplyStateChanges method to synchronize our ObjectSate with EF’s EntityState, so that the context will know how to deal with each and every entity when dealing with entity graphs.

Data.NorthwindContext.SaveChanges()


        public override int SaveChanges()
        {
            this.ApplyStateChanges();
            return base.SaveChanges();
        }


Now when inserting, updating you can explicitly set the entities state, especially useful when dealing with graphs. This abstracts the skill-set of a developer using our Repository of having to know the what, when and how to set the state of entities in the graph in order for the context to update the graph and persist the graph correctly. Let’s take a look at an example of updating an existing Order and adding an OrderDetail item with an entity graph. Both these actions, are will be executed on the same graph, however notice that the action is different for both of the entity’s, one is updating and the other is adding, however we will only be invoking one method (IRepository.Update(TEntity entity) from our IRepository in one transaction.

So we’ll demonstrate and prove out updating an entity graph with our UnitOfWork implementation in these steps.

Code Snippet from LinqPad, notice how we are explicitly setting each of the entities state in the entity graph.


var unitOfWork = new UnitOfWork(this);

var orderId = 10253;

unitOfWork
	.Repository<Order>()
	.Query()
	.Include(t => t.Customer)
	.Filter(t=> t.OrderID == orderId)
	.Get().Dump();

var order = unitOfWork
	.Repository<Order>()
	.FindById(orderId);

unitOfWork
	.Repository<OrderDetail>()
	.Query()
	.Filter(t => t.OrderID == orderId)
	.Get().Dump();

order.ShipName = "Long Le";
order.State = ObjectState.Modified;

order.OrderDetails.Add(
	new OrderDetail{
		ProductID = 2,
		UnitPrice = 10,
		Quantity = 2,
		Discount = 1,
		State = ObjectState.Added
	}
);


unitOfWork.Repository<Order>()
	.Update(order);

unitOfWork.Save();

new UnitOfWork(this)
	.Repository<Order>()
	.Query()
	.Include(t => t.Customer)
	.Filter(t => t.OrderID == orderId)
	.Get().Dump();
	
new UnitOfWork(this)
	.Repository<OrderDetail>()
	.Query()
	.Filter(t => t.OrderID == orderId)
	.Get().Dump();
		

Entity Graph Update Scenario

  1. Query the Order table, make note of the ShipName value.
  2. Query the OrderDetail table, make not there are only three (3) items, that belong to the same Order.
  3. Update the ShipName value in the Order.
  4. Add an OrderDetail to the Order.

5-11-2013 4-13-23 PM

(click image to enlarge)

Presto, we were able to successfully update an existing Order and add a new OrderDetail via an entity graph with one transaction using one method. Now, we can absolutely do this using EF out of the box, however, our goal here is was to abstract the complexity and skill set required from a developer in regards to EF specially how do deal with the DbContext in order to make this happen as well as obviously still support working with graphs through our IRepository implementation.

There you have it, and extensible genericized implementation of the UoW and Repository pattern with EF in MVC. In the next blog post, we’ll add DI & IoC to this solution and introduce the Services layer, this layer will house all of our business logic and rules. We will also implement the Services layer in a way, where we don’t violate our Unit of Work pattern, meaning all the work done in our Repository and Services are executed under one single instance the DbContext per page request.

Happy Coding..! :)

Download sample: https://genericunitofworkandrepositories.codeplex.com