Question

I have a Supplier entity, each Supplier object may reference another Supplier object as its ‘parent’.

public class Supplier
{
    public int? Id { get; set; }

    public virtual Supplier Parent { get; set; }
}

This all works as expected until I attempt to remove the relationship, as in, this supplier no longer has a parent. I can change it from null to a particular supplier and I can set it to a different supplier but setting it to null is not persisted after SaveChanges().

supplier.Parent = null;

The foreign key ‘ParentId’ in the Supplier table is set as nullable. Explicitly defining the relationship doesn’t help.

modelBuilder.Entity<Supplier>().HasOptional(s => s.Parent).WithMany();

I’m sure I’m missing something obvious.

Answer 1

Just found another place in my code where I do the exact same thing (that works) and found this;

// Must access property (trigger lazy-loading) before we can set it to null (Entity Framework bug!!!)
var colour = modelItem.Colour;
modelItem.Colour = null;

Did the same in the new code and it all works.