Entity Framework - Add reference to child object without retrieving entire list of objects?

Question

I have parent object which has childs property which is itself an collection object. ie. Parent.Childs I am exposing these EF object through WCF. Said another way parent can have multiple children as in the case of Invoice(parent) and LineItems (childs).

Client side how do i reference a Child object and add it to the Childs collection without going through the service and getting the entire list of children and setting manually Parent.Childs.Add(child) for each child object that matches.

I would like to do something like Parent.Childs = new Childs(){ new Child{childId=1}, new Child{childId=2}}; and then when i send Parent to server the server knows that a children with id=1 and id=2 already exists and hooks it up. I am sure there is away.

I was reading about EntityKey property but my objects client side do not have this property at all.

thanks

Answer 1

using(var context = new MyEntities())
{
    var child1 = new Child{ childId = 1 };
    context.Children.Attach(child1);
    var parent = new Parent();
    parent.Children.Add(child1);
    context.SaveChanges();
}