MVC 3 EF 4.1 dbContext - Deleting one-to-many data object with non-nullable foreign-key relation

Question

I am using MVC 3, EF 4.1, and dbContext. I need to know how to delete an entity in one-to-many relation with a non-nullable foreign-key.

When I Remove the child entity

Answer 1

I solved the same problem following the section "Cascade Delete Rules on Relationships" at the MSDN guide page here http://msdn.microsoft.com/en-us/library/bb738695.aspx Hope tu be helpfull :D

Answer 2

You can configure the relation to cascade ... this will propagate the delete to dependent entities.

But it's very dangerous :)

I prefer setting a flag in the row that prevents the data tier from including it in future queries, most applications do not need physical delete (and will be a chance to undo).

Answer 3

well, implement your own ICollection and mark those child objects for deletion along with removing it. And then, in your own SaveChanges method override, delete those objects.

Answer 4

I managed to solve the problem as follows:

First, I was able to fetch the ObjectContext by casting my DbContext (eg "ctx") to an IObjectContextAdapter and then obtaining reference to the ObjectContext.

Next, I simply called the DeleteObject method passing the UserContact record to be deleted.

When SaveChanges gets the deletes in the database happen as expected.

if (c.isDeleted == true)  // Deleted UserContact
{
    ObjectContext oc = ((IObjectContextAdapter)ctx).ObjectContext;
    oc.DeleteObject(uc)
}

Here is a snippet of the relevant code:

foreach (var c in model.Contacts)
{
    UserContact uc = null;
    if (c.UserContactId != 0)
    {
        uc = ctx.UserContacts.Find(c.UserContactId);
    }
    if (uc != null)
    {
        if (c.isDeleted == true)  // Deleted UserContact
        {
            ObjectContext oc = ((IObjectContextAdapter)ctx).ObjectContext;
            oc.DeleteObject(uc);
        }
        else  //  Modified UserContact
        {
            uc.userContactData = c.ContactData;
            uc.userContactTypeId = c.ContactType;
            ctx.Entry(uc).State = EntityState.Modified;
        }
    }
    else  // New UserContact
    {
        usr.UserContacts.Add(new UserContact { userContactData = c.ContactData, userContactTypeId = c.ContactType });
    }
}

ctx.Entry(usr).State = EntityState.Modified;
ctx.SaveChanges();

Hope this helps someone in future.