Many-To-Many mappings and key based access

Question

Hi,

i know that i can have two properties on a entity if i have a many-to-one mapping, for example

class User
{
...
public virtual Company {get; set; }
public Guid CompanyId {get; set; }
...
}

which is easy as i have defined the CompanyId as table field anyway.

 

But is such a thing also possible with many-to-many mappings too? If i have a entity like the following:

class TestLoc
{
	...
	public virtual ICollection<Category> TestCategories { get; set; }
	...
}

with a mapping like this

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
	modelBuilder.Entity<TestLoc>()
		.HasMany(x => x.TestCategories)
		.WithMany()
		.Map(m =>
			{
				m.ToTable("TestLocTestCat");
				m.MapLeftKey("TestLocId");
				m.MapRightKey("TestCatId");
			});
}

 

Is it possible that i can access the many-to-many mapping using some Key only method - something like a ICollection<Guid> in paralell with the ICollection<Category> as is need to interact (add, remove) with it sometimes by key only (where loading the whole Category instance is superfluous).

 

Thanks