I went off on a WCF tangent, but am back on EF tonight and will spend some time with you code ASAP.

Thanks for the resources. Looking forward to the POCO article.

Bob

That said, you’ll be glad to know I wrote a sample app in EF 3.5 that does exactly what you’re asking about: http://is.gd/42QlK.
In here you’ll see that you set the Reference propery’s EntityKey in the Create and Update methods of your service. This is necessary in order to relate a new or updated Product with a particular category. As you can see, it is quite clumsy and will no longer be necessary in EF 4.0. But that’s how you do it for now.
Cheers!

was revisitng your app, doing some work with WCF. Where would you do this?

“The proper way to go about it is to set the EntityKey property of the Order’s CustomerReference property, like so:

order.CustomerReference.EntityKey = new EntityKey
(”NorthwindEntities.CustomerSet”, “CustomerID”, od.CustomerID);”

Appreciate it if you have a moment to respond, though I certainly also understand if its been a while since you revisited this.

Bob

Thanks for finding that typo … don’t know how we missed that one!

The way I’ve configured the service reference in each client is to use the change tracking collection for ALL lists. If you have classes that you’re not updating (such as Customer and Product) you can configure the service reference to return List instead and then convert it to the ChangeTrackingCollection (or ChangeTrackngList) only for the items you want to track changes on.

In terms of performance, the initial slow fetch is most likely due to WCF setting up the communication channel. The performance impact of event notifications is negligibl because .NET events are fired only if there are one or more handlers.

I’m happy the sample app is helpful to folks wanting to use LINQ in n-tier apps. I have learned quite a bit about Entity Framework since writing the article, and I plan to incorporate those lessons in a future version of the sample app (coming in the next couple of weeks!).

Cheers,
Tony

I LOVE this app. Here it is a month latter and I’m still playing with it in a variety of incarnations pretty much daily (along with the new CSLA 3.6). Thank you for making it so comprehensive, i.e. all the CRUD operations, 1:M and M:M relationships, etc. Most “sample” apps don’t go to the lengths you have. Thanks for covering ALL the bases for once in a digestable app.

Wanted to point out one critical typo in the EntityDataProvider’s UpdateOrder method. When you build your list of new OrderDetails to be inserted, you have:

List insertedDetails =
(from od in order.OrderDetails
where od.TrackingState == TrackingInfo.Updated
select od).ToList();

TrackingInfo.Updated should be TrackingInfo.Created (As it stands you’ll get duplicate primary key violations).

Sure would be nice to be able to toggle off PropertyChanged and ListChanged notifications when simply fetching data, wouldn’t it. Nice thing about the WinForms version is that BindingList has a RaiseListChangedEvents property that at least allows you to toggle off list changed events. I havn’t stumbled across a WPF counterpart yet though. Fetching is SLOW, and I suspect supressing all the event notifications would be a major performance enhancement.

Thanks again. Back at it tomorrow probably.

Bob

Ah yes, you’ve discovered the missing relationship! What I did was to run the EF wizard but deselect the Customers table. Then right-click on the diagram, select “Update Model from Database” and select the Customers table, removing the association between Customer and Order in the diagram. The end result is that the Order entity contains the CustomerID foreign key, making it much easier to update the Customer of an Order simply by setting the CustomerID property.

The reason I went to all that trouble was that, at the time, I did not know how to update an Order’s Customer property in a disconnected fashion. The proper way to go about it is to set the EntityKey property of the Order’s CustomerReference property, like so:

order.CustomerReference.EntityKey = new EntityKey
(“NorthwindEntities.CustomerSet”, “CustomerID”, od.CustomerID);

I will shortly post a new version of the article sample app which contains this and other improvements.