Master-Detail Data Binding in WPF with Entity Framework

re: Master-Detail Data Binding in WPF with Entity Framework

wagenb — Mon, 13 Jun 2011 19:28:41 GMT

Hi Beth, great video series on WPF/EF. I used your sample to build 2 Master Detail applications for my 1st WPF application. How would I incorporate data validation on the listview data?

re: Master-Detail Data Binding in WPF with Entity Framework

mr anto — Mon, 21 Feb 2011 11:29:10 GMT

hi beth,

im a .Net newbie. My question is: is there a way to create and manage a master/details relation only by VB code?

In my Window.Xaml I created two DataGrids, masterDataGrid and detailsDataGrid, which should be linked to TAB_MASTER and TAB_DETAILS DB tables. No binding is set in my XAML code.

Then, in VB code, I created a DataSet, two CollectionViewSource objects, vMaster and vDetails; I loaded them with data from my tables, and bound them to my data grids by these statements:

masterDataGrid.ItemsSource = vMaster.View

detailsDataGrid.ItemsSource = vDetails.View

when I run my application, data are loaded to the grids; but changing the masterDataGrid selected item, detailsDataGrid is not refreshed. If I create my relation at design time, all works. Where is the bug? Please help, thanks

re: Master-Detail Data Binding in WPF with Entity Framework

Siggy — Sat, 13 Nov 2010 23:54:36 GMT

HI Beth, thanks for your post.

Do you have any posts/videos using a DataGrid rather than a ListView object bound to Entity Framework? I am having problems replicating your master-detail example using a DataGrid and would appreciate being able to work through such an example.

re: Master-Detail Data Binding in WPF with Entity Framework

Anwar — Tue, 02 Nov 2010 05:33:33 GMT

Dear Beth , i have gone through your c# version of masterdetail with Entity framework, the issue is with MasterView.AddNew, when there is data in the order and order details table , your app works fine , but when i deleted the data in both these table, it fails giving the follwing error because MasterView.AddNew.CanAddNew = false.

"'AddNew' is not allowed for this view".

can you please tell me how to overcome this with C#

re: Master-Detail Data Binding in WPF with Entity Framework

Beth Massi — Thu, 02 Sep 2010 20:32:53 GMT

Hi Tim, here are a couple explanations from the EF Team:

1. The POCO template allows for POCO change tracking proxies. This means that when you get an entity form the database, the actual runtime type of the collection navigation properties are going to be EntityCollection<T>, and not the ObservableCollection based collections that you get when you create a new instance of an entity using “new”.

2. EntityCollection<T> implements IListSource.GetList that returns an IBindingList and has AssociationChanged, but the default ObservableCollections you get in new instances don’t. That is proabably why sometimes you see BindingListCollectionView on existing entities and ListCollectionView on new entities.

3. You can use ObjectContext.CreateObject<TEntity>() instead of new to obtain a proxy for a new entity. The proxy will have EntityCollection<T> instances in its collection properties.

4. Not sure what the behavior is for AssociationChanged in added entities, but suspect it won’t help in a detached entity: don’t think you will get AssociationChanged until the new entity gets actually added to its set.

5. While you don’t get AssociatedChanged on the collections of new instances, they are based on ObservableCollection<T>, so you could listen to the CollectionChanged event to learn about changes.

HTH,

-Beth

re: Master-Detail Data Binding in WPF with Entity Framework

Tim — Mon, 23 Aug 2010 19:11:47 GMT

Hi Beth,

I have implemented a version of your example using the POCO Template objects instead of interacting directly with EF. This means I do not have access to the AssociationChanged events in my ObservableCollection.

I am not sure if this is the cause but when I try to add a new MasterRecord the DetailViewSource.View becomes a ListCollectionView instead of a BindingListCollectionView. (In the MasterView_CurrentChanged function.) Can you provide any help?

re: Master-Detail Data Binding in WPF with Entity Framework

Giancarlo — Sat, 08 May 2010 17:14:27 GMT

P.S.: I have tried adding the OMS db to the server using sql server management studio and it works

BUT

if I copy the same db to the project folder and use it in the project to create the OMSmodel etc, this error occurs.

There is something missing because it happens only for the order query, the «Dim customers = From ...» works in both ways.

re: Master-Detail Data Binding in WPF with Entity Framework

Giancarlo — Sat, 08 May 2010 12:36:44 GMT

I have another error which I can't locate.

I run the application in debug, just after the line

---

Dim orders = From o In db.Orders _

Where o.OrderDate >= #1/1/2009# _

Order By o.OrderDate Descending, _

o.Customer.LastName, o.Customer.FirstName _

Select o

---

if I move the mouse over the word "orders" I get the exception error «the name of the column 'Modified' is not valid» (I have translated literally, I have the italian version of vbexpress).

There is no mention of the column in the instruction, the name in the db is correct, I don't understand why an error and, above all, HOW the above instruction is connected to that column.

Thanks

re: Master-Detail Data Binding in WPF with Entity Framework

Beth Massi — Fri, 16 Apr 2010 22:22:17 GMT

@GG @Giancarlo,

The only thing I can suggest is to make sure the database is accessible. Tyr to create a manual connection to it in code. It sounds like EF cannot connect the the database.

You probably want to ask your question on the EF forum:

http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/

HTH,

-B

re: Master-Detail Data Binding in WPF with Entity Framework

Giancarlo — Mon, 12 Apr 2010 20:49:33 GMT

Hi,

I have the same error as GG.

I thought I had made some mistakes so I downloaded the code but I get the same error in

CustomerCollection.vb

Sub New(ByVal customers As IEnumerable(Of Customer), ByVal context As OMSEntities)

MyBase.New(customers)

_context = context

End Sub