EF4 How to expose the join table in a many to many relationship

Question

Say I have the following tables:

Essence, EssenceSet, and Essence2EssenceSet where Essence2EssenceSet holds just the IDs of the 1st 2 tables to form the M:M relationship

Answer 1

You can create M:N relation in EF without retrieving objects as well:

using (var context = new MyContext())
{
   var firstEntity = new FirstEntity { Id = firstId };
   var secondEntity = new SecondEntity { Id = secondId; }

   context.FirstEntities.Attach(firstEntity);
   context.SecondEntities.Attach(secondEntity);

   firstEntity.SecondEntities = new HashSet();
   firstEntity.SecondEntities.Add(secondEntity);

   context.SaveChanges();
}

Anyway exposing junction table as entity is possible but you will lose comfort of EF and fallback to SQL like approach:

1. Delete M:N relation created by designer
2. Add new entity
3. Add two columns to the new entity representing foreign keys
4. Map the new entity to junction table
5. Add associations to related entities
6. Set referential constraints for added relations