Entity Framework 5 - multiple DbContext and a Generic Repository class

Question

All,

I'm using Unit Of Work and Generic Repository patterns for data access in my ASP.NET MVC app with Entity Framework 5. My app worked fine when I only had to deal with 1 database and DbContext.

My problem is, I have a second not-very-closely-related database I need data access for, so I'm assuming I need a second DbContext. However, I don't know how to refactor my Generic Repository to accommodate more than one DbContext. Help!

Here's a simplified look at what I'm attempting so with comments explaining what's failing:

public class UnitOfWork
{
    private Db1Entities db1Context  = new Db1Entities();
    private Db2Entities db2Context = new Db2Entities();

    public GenericRepository<ObjectA> ObjectARepository { // ObjectA is sourced from database 1, so it uses a different DbContext than ObjectB.
        get {
            return new GenericRepository<ObjectA>(db1Context);
        }
    }

    public GenericRepository<ObjectB> ObjectBRepository { // ObjectB is sourced from database 2, so it uses a different DbContext than ObjectA.
        get {
            return new GenericRepository<ObjectB>(db2Context);
        }
    }   
}

public class GenericRepository<T> where T : class
{
    internal DbContext context; // This line and the GenericRepository constructor are my problem. Type DbContext, being a base class, doesn't have the db objects that Db1Entities or Db2Entities have.
                                // When I used to only have to manage 1 DbContext, "context" was type Db1Entities and it worked fine. 
    internal DbSet<T> dbSet;

    public GenericRepository(DbContext context) {
        this.context = context;
        this.dbSet = context.set<T>();
    }

    public virtual T GetByID (int id) {
        // code to return a T object by id...
    }

    // Other repository methods...
}

FYI this is what I'm doing to get by for now. I don't consider it a solution because I'm duplicating "GenericRepository" by copying it as 2 generic repositories, each designed for a different DbContext. I think I ought to be able to use "GenericRepository" and be able to pass it a DbContext rather than making a GenericRepository class for each DbContext... I just don't know how to make it work. See below:

public class UnitOfWork
{
    private Db1Entities db1Context  = new Db1Entities();
    private Db2Entities db2Context = new Db2Entities();

    public GenericDb1Repository<ObjectA> ObjectARepository { // ObjectA is sourced from database 1, so it uses a different DbContext than ObjectB.
        get {
            return new GenericDb1Repository<ObjectA>(db1Context);
        }
    }

    public GenericDb2Repository<ObjectB> ObjectBRepository { // ObjectB is sourced from database 2, so it uses a different DbContext than ObjectA.
        get {
            return new GenericDb2Repository<ObjectB>(db2Context);
        }
    }   
}

public class GenericDb1Repository<T> where T : class
{
    internal Db1Entities  context; 
    internal DbSet<T> dbSet;

    public GenericRepository(Db1Entities context) {
        this.context = context;
        this.dbSet = context.set<T>();
    }

    public virtual T GetByID (int id) {
        // code to return a T object by id...
    }

    // Other repository methods...
}

public class GenericDb2Repository<T> where T : class
{
    internal Db2Entities  context; 
    internal DbSet<T> dbSet;

    public GenericRepository(Db2Entities context) {
        this.context = context;
        this.dbSet = context.set<T>();
    }

    public virtual T GetByID (int id) {
        // code to return a T object by id...
    }

    // Other repository methods...
}

Answer 1

    public class GenericDb1Repository<T, TContext> 
    where T : class
    where TContext : DbContext, new()
{
    internal TContext context; 
    internal DbSet<T> dbSet;

    public GenericRepository(TContext context) {
        this.context = context;
        this.dbSet = context.set<T>();
    }

    public virtual T GetByID (int id) {
        // code to return a T object by id...
    }

    // Other repository methods...
}**