how to annotate a parent-child relationship with Code-First

Question

When using the CTP 5 of Entity Framework code-first library (as announced here) I\'m trying to create a class that maps to a very simple hierarchy table.

Here\'s the SQL

Answer 1

It should work using a mapping like below:

class FamilyContext : DbContext
{
    public DbSet People { get; set; }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        builder.Entity().HasMany(x => x.Children).WithMany().Map(y =>
            {
                y.MapLeftKey((x => x.Id), "ParentID");
                y.MapRightKey((x => x.Id), "ChildID");

            });
    }
}

However that throws an exception: Sequence contains more than one matching element. Apperently that is a bug.

See this thread and the answer to @shichao question: http://blogs.msdn.com/b/adonet/archive/2010/12/06/ef-feature-ctp5-fluent-api-samples.aspx#10102970