EF 4: Removing child object from collection does not delete it - why?

Question

I use Entity Framework 4 and I have parent - child relation with \"Cascade Delete\" set. So i would expect when i remove a child from the parent that the child is deleted wh

Answer 1

If you make the relationship between child and parent an identifying one then you can remove child entities from the collection. You need to make the child's key a composite key containing the primary id key of the parent. That way EF knows it needs to remove the child.

Identifying relationship basically says if the parent doesn't exist then the child has no meaning. This means EF knows it is safe to delete the child when the relationship is removed.

See this question Identifying Relationship and inserting child entities causes "Cannot insert explicit value for identity column in table" and this one Is it possible to remove child from collection and resolve issues on SaveChanges?