Entity Framework - Clear a Child Collection

Question

I have run into an interesting problem with Entity Framework and based on the code I had to use to tackle it I suspect my solution is less than ideal. I have a 1-to-Many rel

Answer 1

Trick: When setting up the relationship between Parent and Child, you'll HAVE TO create a "composite" key on the child. This way, when you tell the Parent to delete 1 or all of its children, the related records will actually be deleted from the database.

To configure composite key using Fluent API:

modelBuilder.Entity().HasKey(t => new { t.ParentId, t.ChildId });

Then, to delete the related children:

var parent = _context.Parents.SingleOrDefault(p => p.ParentId == parentId);

var childToRemove = parent.Children.First(); // Change the logic 
parent.Children.Remove(childToRemove);

// you can delete all children if you want 
// parent.Children.Clear();

_context.SaveChanges();

Done!