Question

I have an Entity Framework v1 project. I have two entities (Roles and Permissions), which have a many-to-many relationship with each other. I pass in a object to be saved (through a WCF call, I do not create it from a context myself), which has new entries in the many-to-many relationship.

I use “context.ApplyPropertyChanges” to update the record with the new properties. I know that this does not update relationships though. I attempt to either do a ChildCollection.Add(relatedObject); or ChildCollection.Attach(relatedObject).

When I use the “Add” method, I get the error that: The object cannot be added to the ObjectStateManager because it already has an EntityKey. Use ObjectContext.Attach to attach an object that has an existing key.

When I use the “Attach” method, I get the error that: The object cannot be added to the ObjectStateManager because it already has an EntityKey. Use ObjectContext.Attach to attach an object that has an existing key.

I am getting quite frustrated, and I think I can hear the Entity Framework laughing at me.

Does anyone know how I can resolve this?

MyRole x = context.Roles.FirstOrDefault(a => a.RoleId == this.RoleId);

context.ApplyPropertyChanges("Roles", this);
foreach (MyPermission p in this.Permissions)
{
     x.Permissions.Add(p);
    //  ^ or v
     x.Permissions.Attach(p);
}
context.SaveChanges();

Thanks.

Answer 1

Wow. After 20 or so straight hours on this problem, I’m starting to hate the Entity Framework. Here is the code that appears to be working currently. I would appreciate any advice on how to make this more streamlined.

I did rework the WCF service so that there is only the one data context. Thanks Craig.

Then I had to change the code to the following:

MyRole x = context.Roles.FirstOrDefault(a => a.RoleId == this.RoleId);

if (x == null) // inserting
{
    MyApplication t = this.Application;
    this.Application = null;
    context.Attach(t);
    this.Application = t;
}
else // updating
{
    context.ApplyPropertyChanges("Roles", this);
    x.Permissions.Load();

    IEnumerable<Guid> oldPerms = x.Permissions.Select(y => y.PermissionId);
    List<MyPermission> newPerms = this.Permissions.Where(y => !oldPerms.Contains(y.PermissionId)).ToList();
    IEnumerable<Guid> curPerms = this.Permissions.Select(y => y.PermissionId);
    List<MyPermission> deletedPerms = x.Permissions.Where(y => !curPerms.Contains(y.PermissionId)).ToList();

    // new 
    foreach (MyPermission p in newPerms)
    {
        x.Permissions.Add(context.Permissions.First(z => z.PermissionId == p.PermissionId));
    }

    // deleted
    foreach (MyPermission p in deletedPerms)
    {
        x.Permissions.Remove(context.Permissions.First(z => z.PermissionId == p.PermissionId));
    }
}