Merge MyDbContext with IdentityDbContext

1. Move the ApplicationUser definition to your DAL.
2. Inherit your MyDbContext from IdentityDbContext<ApplicationUser> or IdentityDbContext
3. OnModelCreating - Provide the foreign key info.
4. Pass MyDbContext while creating the UserManager<ApplicationUser>

It's worth noting that if you merge the DBContexts you are tying an authentication approach (ASP's Identity in this case) to the data access implementation (EF). From a code design point of view that could be seen as mixing your concerns and a violation of Single Responsibility Principle.

That's probably fine in the majority of cases, but if you want to reuse your data layer in other non-web applications (e.g. for a desktop or server app) this will present an issue because IdentityDbContext lives in the Microsoft.AspNet.Identity.EntityFramework namespace and your desktop or server apps are unlikely to be using AspNet Identity as their authentication mechanism.

We were in that situation and ended up keeping ASP's second DB Context, which stayed in the web project. We then cross-loaded some of the data about the user (first name, last name, etc.) into the Identity's claims object when the user signed in.

This may be an old thread, but this article was very helpful in demonstrating how to get the solution to the above question working: http://blogs.msdn.com/b/webdev/archive/2014/03/20/test-announcing-rtm-of-asp-net-identity-2-0-0.aspx

I did end having to include

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

because without it, I would get the following error:

EntityType 'IdentityUserRole' has no key defined. Define the key for this EntityType. EntityType 'IdentityUserLogin' has no key defined. Define the key for this EntityType. EntitySet 'IdentityUserRoles' is based on type 'IdentityUserRole' that has no keys defined. EntitySet 'IdentityUserLogins' is based on type 'IdentityUserLogin' that has no keys defined.

If I add these configurations as mentioned above:

public class IdentityUserLoginConfiguration : EntityTypeConfiguration<IdentityUserLogin>
{
    public IdentityUserLoginConfiguration()
    {
        HasKey(iul => iul.UserId);
    }
}

public class IdentityUserRoleConfiguration : EntityTypeConfiguration<IdentityUserRole>
{
    public IdentityUserRoleConfiguration()
    {
        HasKey(iur => iur.RoleId);
    }
}

it would create an additional foreign key called Application_User.

You may get the following message if you follow the above steps but can't work out how to provide the key information. The error you may receive is:

IdentityUserLogin: : EntityType 'IdentityUserLogin' has no key defined. Define the key for this EntityType. Context.IdentityUserRole: : EntityType 'IdentityUserRole' has no key defined. Define the key for this EntityType.

Create the two following classes

public class IdentityUserLoginConfiguration : EntityTypeConfiguration<IdentityUserLogin>
{

    public IdentityUserLoginConfiguration()
    {
        HasKey(iul => iul.UserId);
    }

}

public class IdentityUserRoleConfiguration : EntityTypeConfiguration<IdentityUserRole>
{

    public IdentityUserRoleConfiguration()
    {
        HasKey(iur => iur.RoleId);
    }

}

In the OnModelCreating method within your Applications DbContext add the two configurations outlined above to the model:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {

        modelBuilder.Configurations.Add(new IdentityUserLoginConfiguration());
        modelBuilder.Configurations.Add(new IdentityUserRoleConfiguration());

    }

This should now get rid of the error methods when your model is being created. It did for me.