ASP MVC EF6 Architecture

Question

We have ASP MVC web project. After reading a lot of articles and discussions here in stackoverflow about the correct architechture we have decided to go with the following one, although there is not only one correct way of doing things this is the way we have decided, but we still have some doubts.

We are publishing this here not only to be helped but also to show what we have done in case it is helpful to somebody.

We are working in ASP .NET MVC project, EF6 Code first with MS SQL Server. We have divided the project into 3 main layers that we have separate into 3 projects: model, service and web.

• The model creates the entities and setup the DataContext for the database.
• The service make the queries to the data base and transform those entities into DTOs to pass them to the web layer, so the web layer doesn't know anything about the database.
• The web uses AutoFac for the DI (dependency Injection) to call the services we have in the service layer and obtain the DTOs to transform those DTOs into Model Views to use them in the Views.

After reading a lot of articles we decided not to implement a repository pattern and unit of work because, in summary, we have read the EF acts as a unit of work itself. So we are simplifying things a little here. https://cockneycoder.wordpress.com/2013/04/07/why-entity-framework-renders-the-repository-pattern-obsolete/

This is the summary of our project. Now I'm going to go through every project to show the code. We are going to show only a couple of entities, but our project has more than 100 different entities.

MODEL

Data Context

public interface IMyContext
{
    IDbSet<Language> Links { get; set; }
    IDbSet<Resources> News { get; set; }
    ...

    DbSet<TEntity> Set<TEntity>() where TEntity : class;
    DbEntityEntry<TEntity> Entry<TEntity>(TEntity entity) where TEntity : class;
}

public class MyDataContext : DbContext, IMyContext
{
    public MyDataContext() : base("connectionStringName") 
    { 

    }

    public IDbSet<Language> Links { get; set; }
    public IDbSet<Resources> News { get; set; }
    ...

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
        modelBuilder.Properties<DateTime>().Configure(c => c.HasColumnType("datetime2"));
    }
}   

Here is how we declare the entities

public class Link
{
    public int Id{ get; set; }
    public string Title { get; set; }
    public string Url { get; set; }
    public bool Active { get; set; }
}

SERVICES

These are the generic classes we use for all the services. As you see we use the DTOs to get data from the web layer. Also we connect to the database using Dbset = Context.Set()

public interface IService
{
}

public interface IEntityService<TDto> : IService where TDto : class
{
    IEnumerable<TDto> GetAll();
    void Create(TDto entity);
    void Update(TDto entity);
    void Delete(TDto entity);

    void Add(TDto entity);
    void Entry(TDto existingEntity, object updatedEntity);
    void Save();
}

public abstract class EntityService<T, TDto> : IEntityService<TDto> where T : class where TDto : class
{
    protected IClientContext Context;
    protected IDbSet<T> Dbset;

    protected EntityService(IClientContext context) { Context = context; Dbset = Context.Set<T>(); }


    public virtual IEnumerable<TDto> GetAll()
    {
        return Mapper.Map<IEnumerable<TDto>>(Dbset.AsEnumerable());
    }

    public virtual void Create(TDto entity)
    {
        if (entity == null)
        {
            throw new ArgumentNullException(nameof(entity));
        }

        Dbset.Add(Mapper.Map<T>(entity));
        Context.SaveChanges();
    }

    public virtual void Update(TDto entity)
    {
        if (entity == null) throw new ArgumentNullException(nameof(entity));
        Context.Entry(entity).State = EntityState.Modified;
        Context.SaveChanges();
    }

    public virtual void Delete(TDto entity)
    {
        if (entity == null) throw new ArgumentNullException(nameof(entity));
        Dbset.Remove(Mapper.Map<T>(entity));
        Context.SaveChanges();
    }


    public virtual void Add(TDto entity)
    {
        Dbset.Add(Mapper.Map<T>(entity));
    }

    public virtual void Entry(TDto existingEntity, object updatedEntity)
    {


        Context.Entry(existingEntity).CurrentValues.SetValues(updatedEntity);
    }

    public virtual void Save()
    {
        Context.SaveChanges();
    }
}

We declare the DTOs in this project (this is a very simple example so we don't have to put all the code here):

public class LinkDto
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Url { get; set; }
    public bool Active { get; set; }
}

Then one of our services:

public interface ILinkService : IEntityService<LinkDto>
{
    IPagedList<LinkDto> GetAllLinks(string searchTitle = "", bool searchActive = false, int pageNumber = 1, int pageSize = 10);
    LinkDto FindById(int id);
    LinkDto Test();
}

public class LinkService : EntityService<Link, LinkDto>, ILinkService
{
    public LinkService(IClientContext context) : base(context) { Dbset = context.Set<Link>(); }

    public virtual IPagedList<LinkDto> GetAllLinks(bool searchActive = false, int pageNumber = 1, int pageSize = 10)
    {
        var links = Dbset.Where(p => p.Active).ToPagedList(pageNumber, pageSize);
        return links.ToMappedPagedList<Link, LinkDto>();
    }

    public virtual LinkDto FindById(int id)
    {
        var link = Dbset.FirstOrDefault(p => p.Id == id);
        return Mapper.Map<LinkDto>(link);
    }

    public LinkDto Test()
    {
        var list = (from l in Context.Links
                    from o in Context.Other.Where(p => p.LinkId == l.Id)
                    select new OtherDto
                    { l.Id, l.Title, l.Url, o.Other1... }).ToList();

        return list;
    }
}

As you see we use AutoMapper (version 5 which has changed a little) to transform from Entities to DTOs the data. One of the doubts we have is if the use of "Dbset.Find" or "Dbset.FirstOrDefault" is correct and also if the use of "Context.Links" (for any entity).

WEB

FInally the web project where we receive the DTOs and transform those DTOs into ModelViews to show in our views.

We need to call, in the Global.asax Application_Start, AutoFac to do the DI so we can use our services.

protected void Application_Start()
{
    ...
    Dependencies.RegisterDependencies();
    AutoMapperBootstrapper.Configuration();
    ...
}

public class Dependencies
{
    public static void RegisterDependencies()
    {
        var builder = new ContainerBuilder();

        builder.RegisterControllers(typeof(MvcApplication).Assembly).PropertiesAutowired();

        builder.RegisterModule(new ServiceModule());
        builder.RegisterModule(new EfModule());

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

public class ServiceModule : Autofac.Module
{
    protected override void Load(ContainerBuilder builder)
    {
        builder.RegisterAssemblyTypes(Assembly.Load("MyProject.Service")).Where(t => t.Name.EndsWith("Service")).AsImplementedInterfaces().InstancePerLifetimeScope();
    }

}

public class EfModule : Autofac.Module
{
    protected override void Load(ContainerBuilder builder)
    {
        builder.RegisterType(typeof(MyDataContext)).As(typeof(IMyContext)).InstancePerLifetimeScope();
    }
}

As you see we also call AutoMapper to configure the different maps.

Then in our controllers we have this.

public class LinksController : Controller
{
    private readonly ILinkService _linkService;
    public LinksController(ILinkService linkService)
    {
        _linkService = linkService;
    }

    public ActionResult Index()
    {
        var links = _linkService.GetAllLinks();
        return View(links.ToMappedPagedList<LinkDto, LinksListModelAdmin>());
    }

...

   public ActionResult Create(LinksEditModelAdmin insertedModel)
    {
        try
        {
            if (!ModelState.IsValid) return View("Create", insertedModel);

            var insertedEntity = Mapper.Map<LinkDto>(insertedModel);
            _linkService.Create(insertedEntity);

            return RedirectToAction("Index");
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }
}

Well, this is it...I hope this can be useful for somebody...and also I hope we can have a little help with the questions we have.

1) Although we are separating database from the web project we do need a reference in the web project to initialize the database and also to inject dependencies, is this correct?

2) Is it correct the approach we have done having our Entities->DTOs->ViewModels? It's a little more work but we have everything separated.

3) In the Service project, when we need to reference a different entity than the main one we are using in the service, is it correct to call Context.Entity? For example, if we need to retrieve also data from the News entity in the links service, is it correct to call "Context.News.Where..."?

4) We do have a little problem with Automapper and EF proxy, because when we call "Dbset" to retrieve data, it gets a "Dynamic proxies" object so Automapper can't find the proper map so, in order to work, we have to set ProxyCreationEnabled = false in the DataContext definition. This way we can get an Entity in order to map it to the DTO. This disables LazyLoading, which we don't mind, but is this a correct approach or there is a better way to solve this?

Thanks in advance for your comments.

Answer 1

For Question no. 2

Entities->DTOs->ViewModels? is good approach because you are doing the clean separation, the programmer can work together with ease. The person who design ViewModels, Views and Controllers don't have to worry about the service layer or the DTO implementation because he will make the mapping when the others developpers finish their implementation.

For Question no. 4

When the flag ProxyCreationEnabled is set to false, the proxy instance will not be created with creating a new instance of an entity. This might not be a problem but we can create a proxy instance using the Create method of DbSet.

using (var Context = new MydbEntities())  
{  
    var student = Context.StudentMasters.Create();  
}  

The Create method has an overloaded version that accepts a generic type. This can be used to create an instance of a derived type.

using (var Context = new MydbEntities())  
{  
    var student = Context.StudentMasters.Create<Student>();  
}  

The Create method just creates the instance of the entity type if the proxy type for the entity would have no value (it is nothing to do with a proxy). The Create method does not add or attach the entity with the context object.

Also i read some where if you set ProxyCreationEnabled = false the child element will not loaded for some parent object unless Include method is called on parent object.