Question

I have a class that contains objects of another class:

public class Container
{
    public BindingList<Item> Items { get; set; }
}
public class Item
{
    ...
}

Objects of the Container are attached to a DbContext. I want to override the DbContext's SaveChanges() to send all changes via a WCF service.

Primitive attributes are no problem. They are reflected in the Entries. But if the relationship between an Item and its Container changes (e.g. a new item is added or an existing item is deleted) there is no entry about that in the ChangeTracker.

I could add a ForeignKey in the Item class to force a Modified entry, but this does not help me much, because I need to know the containing object.

I also tried to convert the DbContext to ObjectContext to get all related items of an entity. But I see no way to get the actual object of a RelatedEnd.

Is there a way to track changes of the contained collection?

Update

As requested, some code I already have:

//In a DbContext subclass
public override int SaveChanges()
{
    //get all modified entities
    var changes = this.ChangeTracker.Entries();
    foreach (var c in changes)
    {
        //check the state of the entity
        switch (c.State)
        {
            //send according WCF callback to the clients
            case System.Data.EntityState.Added:
                App.Current.ServerManager.SendEvent(s => s.EntityAdded((IIdentifiable)c.Entity), causedBy);
                break;
            ...
        }
    }
    return base.SaveChanges();
}

With this code, I cannot detect changes of the Items collection.

Answer 1

Take a look at this question it shows how to get added relationships. Hopefuly it will help you get what you need.