Why do I have 2 Data context classes when creating a controller in EF

Question

I added a database to my project, then I want to add a controller.

When the Add Controller window pops up, I am asked to choose Data context class.

Surprisingly, I found that there are 2 context classes: One is called: my_database_name_dbEntities(projectname)

Another one is called:

ApplicationDbContext(projectname.Models) which is what I created when I added the Entity Framework object which connects to my database.

I am confused about

1. which one to use
2. what are the differences

Here is the screenshot

---

Update

I tried both of them and here is what I have got:

1. If I choose the databasename_dbEntities, VS generates views and controller perfectly with no problems.
2. If I choose ApplicationDbContext, VS throws an error:

Error

There was an error running the selected code generator:

'Unable to retrieve metadata for 'lrc.Event'. One or more validation errors were detected during model generation:

AspNetUserLogin: : EntityType 'AspNetUserLogin' has no key defined. Define the key for this EntityType.

AspNetUserLogins: EntityType: EntitySet 'AspNetUserLogins' is based on type 'AspNetUserLogin' that has no keys defined.

'

Update

Now, I changed the super class from DbContext to IdentityDbContext for the projectname_dbEntities. So it looks like this now:

    public partial class projectname_dbEntities : IdentityDbContext<ApplicationUser>
{
        public projectname_dbEntities()
             : base("projectname_dbEntities", throwIfV1Schema: false)
            //: base("name=projectname_dbEntities")
        {
        }

        public static projectname_dbEntities Create()
        {
            return new projectname_dbEntities();
        }

.....
}

I wonder :

what are the advantages of using the the derived class from IdentityDbContext over the DbContext?

Answer 1

Out of the box, when you create an ASP.NET MVC 5 project using the default template in Visual Studio 2013, you get a basic, ready-to-run website with the elementary Identity and Account management classes already in place.

There is a class ApplicationDbContext. This is the Entity Framework context used to manage interaction between your application and the database where your Account data is persisted (which may, or may not be the same database that will be used by the rest of our application) and this class inherits from IdentityDbContext.

IdentityDbContext is basically a regular DbContext with two DbSets. One for the Users and one for the Roles.

If you don't want use ASP.NET Identity, you can ignore it or mix it into your own DbContext class.