ASP.NET MVC Solution Architecture – Best Practices

Choosing the right architecture for Web Applications is a must, especially for large scale ones. Using the default Visual Studio ASP.NET MVC Web Application project templates, adding controllers with Scaffolding options, just to bootstrap your application and create pages and data in just a few minutes, sounds awesome for sure, but let’s be honest it’s not always the right choise. Peeking all the default options, keeping business, data and presentation logic in the same project will impact several factors in your solutions, such as scalability, usability or testability. In this post, will see how to keep things clean, creating a highly loosely coupled ASP.NET MVC Solution, where Data Access, Business and Presentation layers are defined in the right manner. To do this, we ‘ll make use of several patterns and frameworks, some of those are presented below.

  1. Entity Framework Code First development
  2. Generic Repository Pattern
  3. Dependency Injection using Autofac framework
  4. Automapper

The architecture we will try to build in this post is summarized in the following diagram.
mvc-architecture-01
Let’s start. Assuming we want to built an e-shop Web Application called “Store”, create a blank solution with the same name.

Models

Add a class library project to the solution, named Store.Model. This library is where we ‘ll keep all of our domain objects. Entity Framework will count on them in order to build the database but we are not going to configure Code First using DataAnnotations attributes on this project. Instead, we are going to put all the Code First configuration in specific Configuration classes using the Fluent API. Add a folder named Models and add the following two simple classes.

public class Gadget
    {
        public int GadgetID { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
        public decimal Price { get; set; }
        public string Image { get; set; }

        public int CategoryID { get; set; }
        public Category Category { get; set; }
    }
public class Category
    {
        public int CategoryID { get; set; }
        public string Name { get; set; }
        public DateTime? DateCreated { get; set; }
        public DateTime? DateUpdated { get; set; }

        public virtual List<Gadget> Gadgets { get; set; }

        public Category()
        {
            DateCreated = DateTime.Now;
        }
    }

I preffered to keep the namespace Store.Model instead of the namespace Store.Model.Models

Data Access Layer and Repositories

mvc-architecture-02
The purpose of this layer, is the direct access to the database. It’s the only layer responsible to communicate with the database. If some other layer wants to access the database, then this will be done through some of the classes (repositories) we will define in this project. This will be strictly the only way Add a new class library project named Store.Data and make sure you add a reference to the previous created project, Store.Model. Install Entity Framework using the Nuget Package Manager. First thing we wanna do, is to define the Entity Type Configurations for our domain objecs. Add a folder named Configuration with the following two classes that inherits the EntityTypeConfiguration class.

public class GadgetConfiguration: EntityTypeConfiguration<Gadget>
    {
        public GadgetConfiguration()
        {
            ToTable("Gadgets");
            Property(g => g.Name).IsRequired().HasMaxLength(50);
            Property(g => g.Price).IsRequired().HasPrecision(8, 2);
            Property(g => g.CategoryID).IsRequired();
        }
    }
public class CategoryConfiguration : EntityTypeConfiguration<Category>
    {
        public CategoryConfiguration()
        {
            ToTable("Categories");
            Property(c => c.Name).IsRequired().HasMaxLength(50);
        }
    }

There isn’t any difficult configuration to explain, the point is just to understand where to put the right objects. The next thing we will do is to create the DbContext class that will be responsible to access the database. Add the following class under the root of the current project.

public class StoreEntities : DbContext
    {
        public StoreEntities() : base("StoreEntities") { }

        public DbSet<Gadget> Gadgets { get; set; }
        public DbSet<Category> Categories { get; set; }

        public virtual void Commit()
        {
            base.SaveChanges();
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new GadgetConfiguration());
            modelBuilder.Configurations.Add(new CategoryConfiguration());
        }
    }

We want to seed the database when our application fire up for the first time, so add the following class to the root of the project as well.

public class StoreSeedData : DropCreateDatabaseIfModelChanges<StoreEntities>
    {
        protected override void Seed(StoreEntities context)
        {
            GetCategories().ForEach(c => context.Categories.Add(c));
            GetGadgets().ForEach(g => context.Gadgets.Add(g));

            context.Commit();
        }

        private static List<Category> GetCategories()
        {
            return new List<Category>
            {
                new Category {
                    Name = "Tablets"
                },
                new Category {
                    Name = "Laptops"
                },
                new Category {
                    Name = "Mobiles"
                }
            };
        }

        private static List<Gadget> GetGadgets()
        {
            return new List<Gadget>
            {
                new Gadget {
                    Name = "ProntoTec 7",
                    Description = "Android 4.4 KitKat Tablet PC, Cortex A8 1.2 GHz Dual Core Processor,512MB / 4GB,Dual Camera,G-Sensor (Black)",
                    CategoryID = 1,
                    Price = 46.99m,
                    Image = "prontotec.jpg"
                },
                new Gadget {
                    Name = "Samsung Galaxy",
                    Description = "Android 4.4 Kit Kat OS, 1.2 GHz quad-core processor",
                    CategoryID = 1,
                    Price = 120.95m,
                    Image= "samsung-galaxy.jpg"
                },
                new Gadget {
                    Name = "NeuTab® N7 Pro 7",
                    Description = "NeuTab N7 Pro tablet features the amazing powerful, Quad Core processor performs approximately Double multitasking running speed, and is more reliable than ever",
                    CategoryID = 1,
                    Price = 59.99m,
                    Image= "neutab.jpg"
                },
                new Gadget {
                    Name = "Dragon Touch® Y88X 7",
                    Description = "Dragon Touch Y88X tablet featuring the incredible powerful Allwinner Quad Core A33, up to four times faster CPU, ensures faster multitasking speed than ever. With the super-portable size, you get a robust power in a device that can be taken everywhere",
                    CategoryID = 1,
                    Price = 54.99m,
                    Image= "dragon-touch.jpg"
                },
                new Gadget {
                    Name = "Alldaymall A88X 7",
                    Description = "This Alldaymall tablet featuring the incredible powerful Allwinner Quad Core A33, up to four times faster CPU, ensures faster multitasking speed than ever. With the super-portable size, you get a robust power in a device that can be taken everywhere",
                    CategoryID = 1,
                    Price = 47.99m,
                    Image= "Alldaymall.jpg"
                },
                new Gadget {
                    Name = "ASUS MeMO",
                    Description = "Pad 7 ME170CX-A1-BK 7-Inch 16GB Tablet. Dual-Core Intel Atom Z2520 1.2GHz CPU",
                    CategoryID = 1,
                    Price = 94.99m,
                    Image= "asus-memo.jpg"
                },
                // Code ommitted 
            };
        }
    }

I have ommitted some of the Gadges objects for brevity but you can always download the solution project at the bottom of this post. Now let’s create the Heart of this project. Add a folder named Infrastructure. In order to use the Repository Pattern in the right manner, we need to define a well designed infrastructure. From the bottom to the top all instances will be available through injected interfaces. And the first instance we will require, guess what.. will be an instance of the StoreEntities. So let’s create a factory Interface responsible to initialize instances of this class. Add an interface named IDbFactory into the Infrastructure folder.

public interface IDbFactory : IDisposable
    {
        StoreEntities Init();
    }

You can see that this interface inherits the IDisposable one, so the Concrete class that will implement the IDbFactory interface, must also implement the IDisposable one. To do this in a clean way, add a Disposable class that will implement the IDisposable interface. Then any class that will implement the IDbFactory interface, will just want to inherit this very class.

public class Disposable : IDisposable
    {
        private bool isDisposed;

        ~Disposable()
        {
            Dispose(false);
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
        private void Dispose(bool disposing)
        {
            if (!isDisposed && disposing)
            {
                DisposeCore();
            }

            isDisposed = true;
        }

        // Ovveride this to dispose custom objects
        protected virtual void DisposeCore()
        {
        }
    }

I have highlighted the DisposeCore virtual method cause this method will make others classes inherit this one, to dispose their own objects in the way the need to. Now add the implementation class of the IDbFactory interface.

public class DbFactory : Disposable, IDbFactory
    {
        StoreEntities dbContext;

        public StoreEntities Init()
        {
            return dbContext ?? (dbContext = new StoreEntities());
        }

        protected override void DisposeCore()
        {
            if (dbContext != null)
                dbContext.Dispose();
        }
    }

It’s time to create a generic IRepository interface where we will declare the default operations that our repositories will support. Here I added some that i thought are the most used ones, but you can extend those operations as you wish.

public interface IRepository<T> where T : class
    {
        // Marks an entity as new
        void Add(T entity);
        // Marks an entity as modified
        void Update(T entity);
        // Marks an entity to be removed
        void Delete(T entity);
        void Delete(Expression<Func<T, bool>> where);
        // Get an entity by int id
        T GetById(int id);
        // Get an entity using delegate
        T Get(Expression<Func<T, bool>> where);
        // Gets all entities of type T
        IEnumerable<T> GetAll();
        // Gets entities using delegate
        IEnumerable<T> GetMany(Expression<Func<T, bool>> where);
    }

Notice that the CRUD operations are commented as Mark to do something... This means that when a repository implentation adds, updates or removes an entity, does not send the command to the database at that very moment. Instead, the caller (service layer) will be responsible to send a Commit command to the database through a IUnitOfWork injected instance. For this to be done will use a pattern called UnitOfWork. Add the following two files into the Infrastructure folder.

public interface IUnitOfWork
    {
        void Commit();
    }
public class UnitOfWork : IUnitOfWork
    {
        private readonly IDbFactory dbFactory;
        private StoreEntities dbContext;

        public UnitOfWork(IDbFactory dbFactory)
        {
            this.dbFactory = dbFactory;
        }

        public StoreEntities DbContext
        {
            get { return dbContext ?? (dbContext = dbFactory.Init()); }
        }

        public void Commit()
        {
            DbContext.Commit();
        }
    }

In the same way we used the Disposable class we are going to use an abstract class that has virtual implementations of the IRepository interface. This base class will be inherited from all specific repositories and hence will implement the IRepository interface. Add the following class.

public abstract class RepositoryBase<T> where T : class
    {
        #region Properties
        private StoreEntities dataContext;
        private readonly IDbSet<T> dbSet;

        protected IDbFactory DbFactory
        {
            get;
            private set;
        }

        protected StoreEntities DbContext
        {
            get { return dataContext ?? (dataContext = DbFactory.Init()); }
        }
        #endregion

        protected RepositoryBase(IDbFactory dbFactory)
        {
            DbFactory = dbFactory;
            dbSet = DbContext.Set<T>();
        }

        #region Implementation
        public virtual void Add(T entity)
        {
            dbSet.Add(entity);
        }

        public virtual void Update(T entity)
        {
            dbSet.Attach(entity);
            dataContext.Entry(entity).State = EntityState.Modified;
        }

        public virtual void Delete(T entity)
        {
            dbSet.Remove(entity);
        }

        public virtual void Delete(Expression<Func<T, bool>> where)
        {
            IEnumerable<T> objects = dbSet.Where<T>(where).AsEnumerable();
            foreach (T obj in objects)
                dbSet.Remove(obj);
        }

        public virtual T GetById(int id)
        {
            return dbSet.Find(id);
        }

        public virtual IEnumerable<T> GetAll()
        {
            return dbSet.ToList();
        }

        public virtual IEnumerable<T> GetMany(Expression<Func<T, bool>> where)
        {
            return dbSet.Where(where).ToList();
        }

        public T Get(Expression<Func<T, bool>> where)
        {
            return dbSet.Where(where).FirstOrDefault<T>();
        }

        #endregion
    
    }

Since the implementations marked as virtual, any repository can ovveride a specific operation as required. And now the Concrete repositories: Add a new folder named Repositories and add the following two classes:

public class GadgetRepository : RepositoryBase<Gadget>, IGadgetRepository
    {
        public GadgetRepository(IDbFactory dbFactory)
            : base(dbFactory) { }
    }

    public interface IGadgetRepository : IRepository<Gadget>
    {

    }
public class CategoryRepository : RepositoryBase<Category>, ICategoryRepository
    {
        public CategoryRepository(IDbFactory dbFactory)
            : base(dbFactory) { }

        public Category GetCategoryByName(string categoryName)
        {
            var category = this.DbContext.Categories.Where(c => c.Name == categoryName).FirstOrDefault();

            return category;
        }

        public override void Update(Category entity)
        {
            entity.DateUpdated = DateTime.Now;
            base.Update(entity);
        }
    }

    public interface ICategoryRepository : IRepository<Category>
    {
        Category GetCategoryByName(string categoryName);
    }

You can see that the GadgetRepository supports the default operations using the default behavior and of course that’s OK. On the other hand, you can see an example where a specific repository requires to either extend it’s operations (GetCategoryByName) or overried the default ones (Update). Usually you add a repository for each of your Model classes, hence each repository of type T, is responsible to manipulate a specific DbSet through the DbContext.Set<T>. We are done implementing the Data Access layer so we can procceed to the next one.

Service Layer

mvc-architecture-03
What operations do you want to expose your MVC Controllers? Where is the business logic is going to be implemented? Yeap.. you have guessed right, in this very layer. Add a new class library project named Store.Service. You will have to add references to the two previous created projects, Store.Model and Store.Data. Notice I haven’t told you yet to install Entity Framework to this project.. and I am not going to, cause any database operation required will be done through the injected repositories we created before. Add the first Service file to this project.

// operations you want to expose
    public interface IGadgetService
    {
        IEnumerable<Gadget> GetGadgets();
        IEnumerable<Gadget> GetCategoryGadgets(string categoryName, string gadgetName = null);
        Gadget GetGadget(int id);
        void CreateGadget(Gadget gadget);
        void SaveGadget();
    }

    public class GadgetService : IGadgetService
    {
        private readonly IGadgetRepository gadgetsRepository;
        private readonly ICategoryRepository categoryRepository;
        private readonly IUnitOfWork unitOfWork;

        public GadgetService(IGadgetRepository gadgetsRepository, ICategoryRepository categoryRepository, IUnitOfWork unitOfWork)
        {
            this.gadgetsRepository = gadgetsRepository;
            this.categoryRepository = categoryRepository;
            this.unitOfWork = unitOfWork;
        }

        #region IGadgetService Members

        public IEnumerable<Gadget> GetGadgets()
        {
            var gadgets = gadgetsRepository.GetAll();
            return gadgets;
        }

        public IEnumerable<Gadget> GetCategoryGadgets(string categoryName, string gadgetName = null)
        {
            var category = categoryRepository.GetCategoryByName(categoryName);
            return category.Gadgets.Where(g => g.Name.ToLower().Contains(gadgetName.ToLower().Trim()));
        }

        public Gadget GetGadget(int id)
        {
            var gadget = gadgetsRepository.GetById(id);
            return gadget;
        }

        public void CreateGadget(Gadget gadget)
        {
            gadgetsRepository.Add(gadget);
        }

        public void SaveGadget()
        {
            unitOfWork.Commit();
        }

        #endregion
    
    }

The first and the last highlighted code lines reminds you why we created the IUnitOfWork interface. If we wanted to create a gadget object though this service class, we would write something like this..

// init a gadget object..
gadgetService.CreateGadget(gadget);
gadgetService.SaveGadget();

The other highlighted code lines denotes that any required repository for this service, will be injected through it’s constructor. This will be done through a Dependency Container we will setup in the MVC project’s start up class, using the Autofac framework. In the same way I created the GadgetService.cs file.

 // operations you want to expose
    public interface ICategoryService
    {
        IEnumerable<Category> GetCategories(string name = null);
        Category GetCategory(int id);
        Category GetCategory(string name);
        void CreateCategory(Category category);
        void SaveCategory();
    }

    public class CategoryService : ICategoryService
    {
        private readonly ICategoryRepository categorysRepository;
        private readonly IUnitOfWork unitOfWork;

        public CategoryService(ICategoryRepository categorysRepository, IUnitOfWork unitOfWork)
        {
            this.categorysRepository = categorysRepository;
            this.unitOfWork = unitOfWork;
        }

        #region ICategoryService Members

        public IEnumerable<Category> GetCategories(string name = null)
        {
            if (string.IsNullOrEmpty(name))
                return categorysRepository.GetAll();
            else
                return categorysRepository.GetAll().Where(c => c.Name == name);
        }

        public Category GetCategory(int id)
        {
            var category = categorysRepository.GetById(id);
            return category;
        }

        public Category GetCategory(string name)
        {
            var category = categorysRepository.GetCategoryByName(name);
            return category;
        }

        public void CreateCategory(Category category)
        {
            categorysRepository.Add(category);
        }

        public void SaveCategory()
        {
            unitOfWork.Commit();
        }

        #endregion
    }

And we are done with the service layer as well. Let’s procceed with the last one, the ASP.NET MVC Web Application.

Presentation Layer

mvc-architecture-04
Add a new ASP.NET Web Application named Store.Web choosing the empty template with the MVC option checked. We need to add references to all of the previous class library projects and an Entity Framework installation via Nuget Packages as well. You may be wondering, are we going to write any Entity Framework related queries in this project? Not at all, we need though some of it’s namespaces so we can setup the database configurations for our application, such as the database initializer. And since we started with this, open Global.asax.cs file and add the following line of code to setup the seed initializer we created in the Store.Data project.

protected void Application_Start()
        {
            // Init database
            System.Data.Entity.Database.SetInitializer(new StoreSeedData());

            AreaRegistration.RegisterAllAreas();
            RouteConfig.RegisterRoutes(RouteTable.Routes);
        }

You will also need to create a connection string element to define where you want the database to be created. Add the following element in the Web.config file and changed it accoarding to your development enviroment requirements.

  <connectionStrings>
    <add name="StoreEntities" connectionString="Data Source=(localdb)\v11.0;Initial Catalog=StoreDb;Integrated Security=True" providerName="System.Data.SqlClient" />
  </connectionStrings>

We have made such an effort in the previous steps to create repositories and services but now it’s the time to make them work all together. If you recall, all services contructors have repositories interfaces that must be injected to. The services themeselfs will later be injected in to the controllers conustructors and this is how our application will work. To achieve this, we need to setup Dependancy Injection and for thish reason I decided to use Autofac. Make sure you install Autofac ASP.NET MVC 5 Integration through Nuget Packages.
autofac
Create a Bootstrapper.cs file under the Start_App folder and paste the following code.

public static void Run()
        {
            SetAutofacContainer();
        }

        private static void SetAutofacContainer()
        {
            var builder = new ContainerBuilder();
            builder.RegisterControllers(Assembly.GetExecutingAssembly());
            builder.RegisterType<UnitOfWork>().As<IUnitOfWork>().InstancePerRequest();
            builder.RegisterType<DbFactory>().As<IDbFactory>().InstancePerRequest();

            // Repositories
            builder.RegisterAssemblyTypes(typeof(GadgetRepository).Assembly)
                .Where(t => t.Name.EndsWith("Repository"))
                .AsImplementedInterfaces().InstancePerRequest();
            // Services
            builder.RegisterAssemblyTypes(typeof(GadgetService).Assembly)
               .Where(t => t.Name.EndsWith("Service"))
               .AsImplementedInterfaces().InstancePerRequest();

            IContainer container = builder.Build();
            DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
        }
    }

The code itself is self explanatory. I hope you have followed along with me and you have named your repository and service classes as I did, cause otherwise, this is not gonna work. There are two importants things left to complete the tutotiral. The first one to define ViewModel classes and set Automapper to map domain entities to viewmodels and backwards. The second one is to see how to setup CSS Bootstrap in our web application. I suppose most of you, install bootstrap from Nuget Packages and start adding css and script references to your project. Here though we will follow a different approach.

CSS Bootstrap

First of all download Boostrap distribution from the official site. Add three folders to your application named css, fonts and js respectively. In the css folder paste the bootstrap.css file from what you have downloaded, in the fonts folder paste everything is inside the respective fonts folder and in the js folder, just paste the bootstrap.js file. We are going to use Bundling and Minification for bootstrap and to achieve that you need to install Microsoft ASP.NET Web Optimazation Framework through Nuget Packages.
web-optimazation
When you finish installing this, add a new class named BundleConfig into the App_Start folder as follow:

public class BundleConfig
    {
        public static void RegisterBundles(BundleCollection bundles)
        {
            bundles.Add(new ScriptBundle("~/bootstrap/js").Include("~/js/bootstrap.js", "~/js/site.js"));
            bundles.Add(new StyleBundle("~/bootstrap/css").Include("~/css/bootstrap.css", "~/css/site.css"));

            BundleTable.EnableOptimizations = true;
        }
    }

As you can see I have also referenced site.js and site.css javascript and css files. Those files can host any bootstrap css customazations you wanna do or any javascript related code. Feel free to add the respective files and leave them empty. Now we need to declare that we want MVC to use bundling and minication, so add the following line into the Global.asax.cs file.

protected void Application_Start()
        {
            // Init database
            System.Data.Entity.Database.SetInitializer(new StoreSeedData());

            AreaRegistration.RegisterAllAreas();
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            // Autofac and Automapper configurations
            Bootstrapper.Run();
        }

Notice that I have also called the Bootstrapper.Run() function that will setup the Autofac’s configuration we made before. This function will also configure Automapper, something we gonna see in a bit. Let’s finish with Bootrap for now. We will need a Layout to use for our application, so go and create a Shared folder under the Views folder and add a new item of type MVC 5 Layout Page (Razor) named _Layout.cshtml.

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>@ViewBag.Title</title>
    <!-- Bootstrap -->
    @Styles.Render("~/bootstrap/css")
    <!--[if lt IE 9]>
    <script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/
    html5shiv.js"></script>
    <script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/
    respond.min.js"></script>
    <![endif]-->
</head>
<body>
    <nav id="myNavbar" class="navbar navbar-default navbar-inverse navbar-fixed-top" role="navigation">
        <!-- Brand and toggle get grouped for better mobile display -->
            <div class="navbar-header">
                <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#navbarCollapse">
                    <span class="sr-only">Toggle navigation</span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
                @Html.ActionLink("Store", "Index", "Home", new { }, new { @class = "navbar-brand" })
            </div>
            <!-- Collect the nav links, forms, and other content for toggling -->
            <div class="collapse navbar-collapse" id="navbarCollapse">
                <ul class="nav navbar-nav">
                    <li class="active">
                        @Html.ActionLink("Tablets", "Index", "Home", new { category = "Tablets" }, null)
                    </li>
                    <li class="active">
                        @Html.ActionLink("Laptops", "Index", "Home", new { category = "Laptops" }, null)
                    </li>
                    <li class="active">
                        @Html.ActionLink("Mobiles", "Index", "Home", new { category = "Mobiles" }, null)
                    </li>
                </ul>
            </div>
    </nav>
    @RenderBody()
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
    @Scripts.Render("~/bootstrap/js")
</body>
</html>

The page will probably complain that cannot resolve Razor syntax so you have to add the following using statement in the web.config file which is under the Views folder (not application’s web.config). Following is part of that file..

<namespaces>
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Routing" />
        <add namespace="Store.Web" />
        <add namespace="System.Web.Optimization" />
      </namespaces>

Automapper

In a real application your domain objects will probably have a lot of properties but you only want to display some of them in the browser. More over when posting back to server, for example when creating objects though a form element, you also want to post only a few of the domain object’s properties. For this reason you define ViewModel objects and use them instead of the real domain ones. Make sure you install Automapper from Nuget Packages.
automapper
Add a new folder named ViewModels with the following classes.

public class GadgetViewModel
    {
        public int GadgetID { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
        public decimal Price { get; set; }
        public string Image { get; set; }

        public int CategoryID { get; set; }
    }
public class CategoryViewModel
    {
        public int CategoryID { get; set; }
        public string Name { get; set; }

        public List<GadgetViewModel> Gadgets { get; set; }
    }
public class GadgetFormViewModel
    {
        public HttpPostedFileBase File { get; set; }
        public string GadgetTitle { get; set; }
        public string GadgetDescription { get; set; }
        public decimal GadgetPrice { get; set; }
        public int GadgetCategory { get; set; }
    }

When your ViewModel classes have properties named as the respective domain objects, Automapper is smart enough to make the mapping through default conventions. Otherwise you have to set the mapping manualy by yourself. Notice the last class I have added, the GadgetFormViewModel. We can make a convetion to add a “Form” word before “ViewModel” so that we know that this type of view model, is posted back to server through a form element. Let’s now configure the mappings. Add a new folder Mappings and add the following class file.

public class AutoMapperConfiguration
    {
        public static void Configure()
        {
            Mapper.Initialize(x =>
            {
                x.AddProfile<DomainToViewModelMappingProfile>();
                x.AddProfile<ViewModelToDomainMappingProfile>();
            });
        }
    }

We haven’t created the required profiles yet but we will in a bit. What I wanted to show you is that you can create as many Automapper profiles you want and then add them into Mapper.Initialize function. Here we will define two profiles, one to map domain models to ViewModels and another one for backwards. Add the following classes in the same folder as the previous.

public class DomainToViewModelMappingProfile : Profile
    {
        public override string ProfileName
        {
            get { return "DomainToViewModelMappings"; }
        }

        protected override void Configure()
        {
            Mapper.CreateMap<Category,CategoryViewModel>();
            Mapper.CreateMap<Gadget, GadgetViewModel>();
        }
    }
public class ViewModelToDomainMappingProfile : Profile
    {
        public override string ProfileName
        {
            get { return "ViewModelToDomainMappings"; }
        }

        protected override void Configure()
        {
            Mapper.CreateMap<GadgetFormViewModel, Gadget>()
                .ForMember(g => g.Name, map => map.MapFrom(vm => vm.GadgetTitle))
                .ForMember(g => g.Description, map => map.MapFrom(vm => vm.GadgetDescription))
                .ForMember(g => g.Price, map => map.MapFrom(vm => vm.GadgetPrice))
                .ForMember(g => g.Image, map => map.MapFrom(vm => vm.File.FileName))
                .ForMember(g => g.CategoryID, map => map.MapFrom(vm => vm.GadgetCategory));
        }
    }

For the Domain -> ViewModels mapping we didn’t need to setup anything. Automapper will use the default conventions and that’s fine. For our GadgetFormViewModel -> Gadget mapping though, we set manually the configuration as shown above. The last thing remained to finish with Automapper is to add the following line in the Bootstrapper class.

public static class Bootstrapper
    {
        public static void Run()
        {
            SetAutofacContainer();
            //Configure AutoMapper
            AutoMapperConfiguration.Configure();
        }
// Code ommitted 

Controllers and Views

We are almost finished. Add a new MVC Controller named HomeController and paste the following code.

public class HomeController : Controller
    {
        private readonly ICategoryService categoryService;
        private readonly IGadgetService gadgetService;

        public HomeController(ICategoryService categoryService, IGadgetService gadgetService)
        {
            this.categoryService = categoryService;
            this.gadgetService = gadgetService;
        }

        // GET: Home
        public ActionResult Index(string category = null)
        {
            IEnumerable<CategoryViewModel> viewModelGadgets;
            IEnumerable<Category> categories;

            categories = categoryService.GetCategories(category).ToList();

            viewModelGadgets = Mapper.Map<IEnumerable<Category>, IEnumerable<CategoryViewModel>>(categories);
            return View(viewModelGadgets);
        }
    }

Now you can see in action why we have made such an effort to setup Repositories, Services, Autofac and Automapper. Services will be injected in the controller for each request and their data will be mapped to ViewModels before send to the Client. Right click in the Index action and add a View named Index with the following code. I must mention here, that the gadgets objects we use, have image references to a folder named images in the Web Application project. You can use your images or just download this project at the end of this post.

@model IEnumerable<Store.Web.ViewModels.CategoryViewModel>

@{
    ViewBag.Title = "Store";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<p>

</p>
<div class="container">
    <div class="jumbotron">

        @foreach (var item in Model)
        {
            <div class="panel panel-default">
                <div class="panel-heading">
                    @*@Html.DisplayFor(modelItem => item.Name)*@
                    @Html.ActionLink("View all " + item.Name, "Index", new { category = item.Name }, new { @class = "pull-right" })
                    @using (Html.BeginForm("Filter", "Home", new { category = item.Name }, FormMethod.Post, new { @class = "navbar-form" }))
                    {
                        @Html.TextBox("gadgetName", null, new { @class = "form-control", placeholder = "Search in " + item.Name })
                    }


                </div>
                @foreach (var gadget in item.Gadgets)
                {
                    @Html.Partial("Gadget", gadget)
                }
                <div class="panel-footer">
                    @using (Html.BeginForm("Create", "Home", FormMethod.Post,
                            new { enctype = "multipart/form-data", @class = "form-inline" }))
                    {
                        @Html.Hidden("GadgetCategory", item.CategoryID)
                        <div class="form-group">
                            <label class="sr-only" for="file">File</label>
                            <input type="file" class="form-control" name="file" placeholder="Select picture..">
                        </div>
                        <div class="form-group">
                            <label class="sr-only" for="gadgetTitle">Title</label>
                            <input type="text" class="form-control" name="gadgetTitle" placeholder="Title">
                        </div>
                        <div class="form-group">
                            <label class="sr-only" for="gadgetName">Price</label>
                            <input type="number" class="form-control" name="gadgetPrice" placeholder="Price">
                        </div>
                        <div class="form-group">
                            <label class="sr-only" for="gadgetName">Description</label>
                            <input type="text" class="form-control" name="gadgetDescription" placeholder="Description">
                        </div>
                        <button type="submit" class="btn btn-primary">Upload</button>
                    }
                </div>
            </div>
        }

    </div>

</div>

Two things to notice here. The first one is that we need to create a Partial view to diplay a GadgetViewModel object and the second one is the Form’s control element’s names. You can see that they much our GadgetFormViewModel properties. Under the Shared folder create the following Partial view for displaying a GadgetViewModel object.

@model Store.Web.ViewModels.GadgetViewModel

<div class="panel-body">
    <div class="media">
        <a class="pull-left" href="#">
            <img class="media-object" src="../../images/@Model.Image" />
        </a>
        <div class="media-body">
            <h3 class="media-heading">
                @Model.Name
            </h3>
            <p>@Model.Description</p>
        </div>
    </div>
</div>

In the Index.cshtml page I have added search and filter functionality and Create gadget as well. To achieve that you need to add the following Action methods to the HomeController.

public ActionResult Filter(string category, string gadgetName)
        {
            IEnumerable<GadgetViewModel> viewModelGadgets;
            IEnumerable<Gadget> gadgets;

            gadgets = gadgetService.GetCategoryGadgets(category, gadgetName);

            viewModelGadgets = Mapper.Map<IEnumerable<Gadget>, IEnumerable<GadgetViewModel>>(gadgets);

            return View(viewModelGadgets);
        }

        [HttpPost]
        public ActionResult Create(GadgetFormViewModel newGadget)
        {
            if (newGadget != null && newGadget.File != null)
            {
                var gadget = Mapper.Map<GadgetFormViewModel, Gadget>(newGadget);
                gadgetService.CreateGadget(gadget);

                string gadgetPicture = System.IO.Path.GetFileName(newGadget.File.FileName);
                string path = System.IO.Path.Combine(Server.MapPath("~/images/"), gadgetPicture);
                newGadget.File.SaveAs(path);

                gadgetService.SaveGadget();
            }

            var category = categoryService.GetCategory(newGadget.GadgetCategory);
            return RedirectToAction("Index", new { category = category.Name });
        }

I am sure that at this point you understand the purpose of all the above code so I won’t explain anything. You need to add a Filter page so right click in the Filter action and create the following View.

@model IEnumerable<Store.Web.ViewModels.GadgetViewModel>

@{
    ViewBag.Title = "Filter";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<div class="container">
    <div class="jumbotron">

        @foreach (var item in Model)
        {
            <div class="panel panel-default">
                <div class="panel-heading">
                    @Html.Label(item.Name)
                </div>
                @Html.Partial("Gadget", item)
            </div>
        }

    </div>
</div>

mvc-architecture-05
You can filter gadgets by category or search gadgets in a specific category. That’s it, we have finished creating a highly decoupled architecture that could support large scale MVC applications.

Github

I have decided to move all of my code to my Github account so you can download most of the projects that we have seen on this blog from there. You can download this project from here. I hope you enjoyed this post as much as I did.

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Categories: ASP.NET, Best practices

Tags: , ,

137 replies

  1. Thank you for this article.
    I have a question. In service layer, Repository and UnitOfWork have their own dbContext, so how can the UnitOfWork commit the session that was handled by the Repository?

    • Good question. It’s actually the same dbContext instance that comes from the unique injected DbFactory instance per request. Chears to Autofac!

      var builder = new ContainerBuilder();
      builder.RegisterControllers(Assembly.GetExecutingAssembly());
      builder.RegisterType<UnitOfWork>().As<IUnitOfWork>().InstancePerRequest();
      builder.RegisterType<DbFactory>().As<IDbFactory>().InstancePerRequest();
      
      • Was scratching my head over this for two days, forgot to add InstancePerRequest in my project. Thanks for the clarification.

  2. Thanks for your awesome article!

    I’m currently setting up my third MVC Project using your tutorial 🙂

    it was really easy to follow your guide and to adapt it for my requirements!

  3. Thanks a lot for this excellent article.
    I’ll be using this architecture style in my next MVC project – really committed to you for sharing this sample.

  4. Can I use Dapper instead of Entity Framework in this architecture?

  5. Hi,
    I have a question about DI.
    How to know which classes will be injected the objects? We need to config this or all of classes that has constructor with registered object parameter will be injected?

  6. Great post! Thank you Christos. One suggestion: took me a little while to figure out why my Web Api controllers were throwing a “default constructor not found” exception and realize that a separate Autofac dependency and a couple extra lines of configuration were needed. Maybe mention somewhere that if the dev likes to include Web Api controllers in their project, they need to reference Autofac.WebApi2 and then in the Bootstrapper, RegisterApiControllers() and also set the GlobalConfiguration.Configuration.DependencyResolver to Autofac Web Api resolver.

  7. For the icing on the cake, we can do small addition to this solution i.e. Data hiding Approach. We can hide the reference of Models in the Web Project

  8. Simply brilliant. A good way for newcommers to asp.net to dive into architectures! Thank you!

  9. Brilliant! Thank you very much for this guide! Great for newcomers (as myself) to learn more about architecting an asp.net mvc app.

  10. Nice Article easy to understand

  11. Thank you sir for this article. Really a great article. It is easy to understand

  12. Hi Christos,
    Thanks for this amazing post! Can you please let me know if you have an example of using FluentValidation on the ‘FormViewModel’ classes? Thanks.

  13. Can you please share, how to write test cases for this architecture.

  14. Well written article! Thanks for sharing. I’ll need to examine much more closely when I have some time😃

  15. This is by far the most thorough and complete tutorial on Repository/Unit of Work pattern I’ve seen on the web. All other examples I’ve seen are partial and don’t go into other areas beyond the infrastructure. I’ve heard of Autofac/Automapper before, but never saw them as “the glue” to make it all work because they were never covered this way. Now, if you would only include a “Domain Driven Design” pattern, I would be in 7th Heaven, lol…

  16. thanks the article! how to create key attribute indentity in model?

  17. Very nice article. Thanks. I’m going to extend it so the services become REST services using the Web API.

  18. I didn’t want to use z default architecture of MVC. And I was looking for N-tier architecture. I really appreciate the way you put everything. This is the best article I’ve seen so far. Thanks a lot!

  19. Can you explain why we can’t have the following code in the Create method of the Service class:

    public void CreateCategory(Category category)
    {
        categorysRepository.Add(category);
        unitOfWork.Commit();
    }
    

    This is a service class so, in my opinion, if a caller invoke this method they expect a new entity goes to a database instead of marking it as ‘new’.
    For what purpose a caller needs to remember to invoke two methods in a controller: CreateCategory and SaveCategory?

    • Who said you can’t? It’s up to your application’s requirements the way you will implement the data access layer.
      A service method is responsible for a specific job and a caller may needs to commit multiple changes in the context of a transaction.
      e.g.

      1. Start transaction
      2. Call service method 1
      3. Call service method 2
      4. unitOfWork.Commit (rollbacks on error..)
  20. Not sure how to use this with the asp.net users/roles. Wouldn’t this drop the asp membership tables? Is there a way around this?

  21. Hi Christos,

    Brilliant post as always.

    Any chance you know the best strategy of incorporating Asp.net identity into this structure?. In my personal projects, when i include Asp.net Identity using this architecture, I’m finding that no matter what i try, Visual studio always prompts me to add Microsoft.asp.net.identity.EntityFramework dll (i think its that), in the mvc project. Which is not what i want as i want the MVC project to be agnostic and not be coupled to a specific database implementation.

    I hope that made sense.

    Thanks.

    • Hi Imran,

      Have you received any suggestion on incoprporating this architecture using asp.net identity ? If so, please update me on the resources.

  22. Very good article. The mapping between viewmodel and domain entities happening in asp.net mvc Ui layer. Why my asp.net mvc layer referring domain entities ?. Instead can we pass viewmodels to service layer and resolve the mapping in service so that business domains are secure and not exposed to any Ui layers. Can you plz clarify? Have a healthy life. Thanks

    • Hi Bhaskar, very good point.
      Of course you can move the mappings into the service layer and let services return ViewModels.
      Keep in mind though that this may cause you issues in case another component needs to use the service in a different way. For example a Web API layer may wants to expose more or less properties from the domain entities than the ViewModels we created.
      The important thing to remember is that the Web or a possible API layer should access the database only through the service layer.

      • Hi Chris, can I ask you one question? How would you name this middle layer between ASP.NET MVC Controllers and Services? And where better place for this classes/project. I would like to avoid of mapping Domain Models and Presentations’ View Models in Controllers… I wonder, is there any good practice? Thanks.

      • what do you think about next abstraction like BLL?

        DB -> Repositories Business Logic Layer Services Controllers

        mapping and etc. in services and services works with BLL, whereas some WebApi project can work directly with BLL

  23. Can I apply this solution architecture if I have 2 or multiple databases?

  24. Hi, thank you very much, awesome article!

  25. Thank you for your effort on this tutorial but I have a question.

    Assume that I have two entities that have many – many relationship. How do I implement it in my service layer?

  26. Hello,
    Sir, what do you think of implementing ASP.NET Identity with generic repository pattern?
    Have you ever tried to do that?
    Maybe you plan to write an article about it?

    I am working on it and I have to admit that it is difficult…
    Do you have any interesting samples/articles to resolve this issue?

    Thank you in advance for the answer.

  27. awsome sir!

  28. Excellent work. Happy thanksgiving

  29. Thank You. It’s amazing

  30. Hi Sir, amazing article!
    I have one question, Where do you create the object of: ICategoryRepository and IUnitOfWork?
    I made somwhing like this but is not well:

    public CategoryService(ICategoryRepository categorysRepository, IUnitOfWork unitOfWork)
    {
    IDbFactory df = new DbFactory();
    this.categorysRepository = new CategoryRepository(df);
    this.unitOfWork = new UnitOfWork(df);
    }

    • Check Presentation Layer part,

      The services themeselfs will later be injected in to the controllers constructors and this is how our application will work. To achieve this, we need to setup Dependancy Injection and for thish reason I decided to use Autofac. Make sure you install Autofac ASP.NET MVC 5 Integration through Nuget

      • Hoo good!
        Why did you inject the repository on the presentation layer and not in the aervice layer?

      • I dont know, I have the same question for Chris S. I already have implemented it on one project and i had must added repositories layer reference on presentation layer.

        I am waiting for Chris S answer.

      • We need to add the reference in order to set the Dependency Injection and this is done in the Bootstrapper.cs of the Store.Web project. Referencing the repositories layer doesn’t mean that you use the repositories in the controllers. We inject the services and through them we have access to the database.

      • Thanks Chris.

      • It is good questions about why the presentation layer should know about Repositories. It allows developers to use classes(repositories) directly (without services). I know that it is the pattern. If I have multiple DLLs where I need IoC, so should the PL know all them??? I will be looking for a workaround further.

  31. Great article!!
    I already have implemeted on my last recent project(invoice online)
    I used NHibernate instead of EntityFramework

  32. Is there a name for this architecture type? Are there other references for it?

  33. hello thank you for the article, but how should we handle the complexity that appears when we try to save complex(3 levels or more) parent model and add /update/delete it’s nested items ?

  34. Very nice article
    but just one question why you have used this code :
    public StoreEntities DbContext
    {
    get { return dbContext ?? (dbContext = dbFactory.Init()); }
    }

    in your unit of work directly?

    was it better to abstract StoreEntities one leve then use the abstraction in UOW?

  35. Hi, Thanks for sharing this with us. I was wondering if this approach is needed with MVC 6 ASP.NET 5 since there was an improvements in DI using Service container. Thanks

  36. Hey Chris, can you update this article using Asp.net MVC 6 (Core version). DI pattern is by default implemented in that. Or if you explain how to layout web application architecture without using extra nuget packages.

  37. Hey Chris, what do you think about the idea of putting all repositories as properties inside UnitOfWork, and accessing them using unitOfWork.Gadgets or unitOfWork.Categories? I saw and example like this in a course.

    Is it strictly necessary to have all operations called by Controllers in ServiceLayer? Because there are so simple operations that it would be called directly from the repositories. Would it be a bad practice? Why?

    Hey guys, you can also answer to me, not only Chris 🙂

    Take care!

  38. this post is by far the best out there.
    I went to this Microsoft conference and the speaker was talking about unit of work and how your controllers need to be lesser code. I understand why, just that he did not give us samples.

    I think this is what he was talking about.

  39. Hi.. I think best architeture is to write minimum code to get maximum output with re-usability and also with taking care of light-weight, you have written a lot code for just 2 entities.

    Thanks.

  40. When you add a new entitity, is there a way to get the id of the newly inserted row? From you examples both Add, and Save/Commit return void.

  41. It’s very useful articles thanks for you. Can you see us how we can do this in case database first please.

  42. Hello, would this architecture stay good using the EF database first approach
    Regards, and great article !

  43. excellent post. Thanks sir

  44. Really Nice article Christos… Thnx a lot.

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Chara Plessa

The purpose of this blog is to broaden my education, promote experimentation and enhance my professional development. Albert Einstein once said that “If you can’t explain it simply, you don’t understand it well enough” and I strongly believe him!

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