EF DbContext and Ninject

Question

I asked a question a while back about why the default equality comparer didn't seem to work when I was union two collections of entities.

EF Code First - Linq to Entities Union EqualityComparer

The answer was due to the fact that I was using two difference instances of my DbContext hence different references.

So now I am trying to share my DbContent across the request. I see a few "complicated" examples but I thought I'd try for a more simple solution.

So I created a IDbContext interface which simply outlines my Entities

public interface IDbContext {
   int SaveChanges();
   DbSet<News> News { get; set; }
   DbSet<Category> Categories { get; set; }
}

My DbContext is then implement like this:

public class SiteContext : DbContext, IDbContext {
   public DbSet<News> News { get; set; }
   public DbSet<Category> Categories { get; set; }

   protected override void OnModelCreating(DbModelBuilder modelBuilder) {
      ...
   }
}

Then in my two repositories (NewsRepository and CategoryRespository) I have the IDbContext as a constructor parameter

IDbContext _db;

public NewsRepository(IDbContext db) {
    _db = db;
}

So now I assume that if I bind IDbContext to SiteContext in the request scope my repositories will share the same context?

 kernel.Bind<IDbContext>().To<SiteContext>().InRequestScope();

However, when I try my union again from the previous question I still receive duplicate entities! What I am doing wrong? How can I tell if I am definitely using the same context in one request?

Answer 1

Because when each repository is constructed Ninject will is providing you with a new instance of SiteContext per repository. Thats why its not working. Its a good idea to use a unitofwork implementation which means all repositories use the same context.
The UnitOfWork would take in a IDbContext on construction.

Some thing like this would work

private IDbContext _context;

public UnitOfWork(IDbContext context)
{
    _context = context
}

private _INewsRepository;
public INewsRepoitory 
{
    get{
         if(_INewsRepository == null)
         {
              _INewsRepository = new NewsREpository(_context);
              return _INewsRepository;
         }
         else
         {
              return _INewsRepository;
         }    
}

Answer 2

To improve the solution of feanz I would still do property injection of the INewsRepository with Ninject:

[Inject]
public INewsRepository NewsRepo {get;set;}

Every time an IUnitOfWork is created there is also an INewsRepository created. This must still be added to your ninject bindings.