Question

I am trying to figure out how to prevent Entity Framework from creating a composite primary key on one of my tables. I have the following two entities:

public class Entry
{
   public Int64 EntryID { get; set; }
   public string UserName { get; set; }
   public string EntrySubject { get; set; }
}

public class Revision
{
   public Int64 RevisionID { get; set; }
   public string RevisionDescription { get; set; }

   public Int64 EntryID { get; set; }
   public Entry Entry { get; set; }
}

When Entity Framework generates the database, the Revisions table gets a composite primary key made up of RevisionID and EntryID. I would like the primary key for the Revisions table to be RevisionID only. Is there a way to do that? (I am using Entity Framework 4.3 with SQL Server CE, if that makes a difference.)

Answer 1

You can create a Key Data Annotation in your Revision class, to explicitly define your key:

public class Revision
{
   [Key]
   public Int64 RevisionID { get; set; }
   public string RevisionDescription { get; set; }

   public Int64 EntryID { get; set; }
   public Entry Entry { get; set; }
}

or using Fluent:

modelBuilder.Entity<Revision>().HasKey(r=>r.RevisionID)

EDIT: Added test app and diagram

I created a test app, with a Key annotation and it created the following database, with a primary key on Revisions table with only RevisionID

Entirety of the app:

namespace ExampleCF
{
    public class Entry
    {
        public Int64 EntryID { get; set; }
        public string UserName { get; set; }
        public string EntrySubject { get; set; }
    }

    public class Revision
    {
        [Key]
        public Int64 RevisionID { get; set; }
        public string RevisionDescription { get; set; }

        public Int64 EntryID { get; set; }
        public Entry Entry { get; set; }
    }

    public class ItemContext : DbContext
    {
        public DbSet<Entry> Entrys { get; set; }
        public DbSet<Revision> Revisions { get; set; }

        protected override void OnModelCreating(System.Data.Entity.DbModelBuilder modelBuilder)
        {

        }
    }   

    class Program
    {
        public static void Main()
        {
        }

    }
}