DevForce 2010: Lazy load sort order

Lazy load sort order

Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce 2010
Forum Discription: For .NET 4.0
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=2872
Printed Date: 16-Aug-2026 at 8:16am

Topic: Lazy load sort order

Posted By: Togas
Subject: Lazy load sort order
Date Posted: 08-Aug-2011 at 7:23am

Is there a way to set the sort order when you are using lazy loading?

Replies:

Posted By: sbelini
Date Posted: 09-Aug-2011 at 3:45pm

Hi Togas,

Try

aCustumer.Orders.OrderBy(ord => ord.Freight)

Regards,

Silvio.

Posted By: Togas
Date Posted: 10-Aug-2011 at 7:16am

Silvio,

Where would I put that? My initial thought was that should be part of my initial load query but my child table isn't an option when I query the parent table and I also noticed you are only referencing a single customer.

The 2 tables are linked in my model

Posted By: sbelini
Date Posted: 10-Aug-2011 at 11:39am

Hi Togas,

I assume that if you want to sort the order of a navigation property (i.e. lazy loading) you are probably binding it to something.

If you want to load related entities during your initial load query, then you will need to use .Include:

var initialLoadQuery = mgr.Customer

.Include("Orders");

in the case above, Orders are not being ordered because it's not bound to anything. (it was simply loaded in the EntityCache using eager loading)

Could you explain in detail what you are trying to accomplish, so I can better understand your issue?

Regards,

Silvio.

Posted By: Togas
Date Posted: 10-Aug-2011 at 11:50am

Your assumption was correct, I'm binding to a datagrid. It's a basic Master-Detail type page.

<sdk:DataGrid AutoGenerateColumns="False" 
	ItemsSource="{Binding SelectedOrder.OshkoshEquipments}"
	SelectedItem="{Binding SelectedEquipment, Mode=TwoWay}">

...

</sdk:DataGrid>

Here is the relevant code from my view model

Public Property OshkoshOrders As ObservableCollection(Of Oshkosh)

Private Sub LoadData

      OshkoshOrders = New ObservableCollection(Of Oshkosh)
 
      Dim qOrders = _mgr.Oshkoshes
      qOrders.ExecuteAsync(Sub(o)
                             If o.HasError Then
                               Throw New InvalidOperationException("Query failed")
                             End If
                             o.Results.ForEach(Sub(oe)
                                                 OshkoshOrders.Add(oe)
                                               End Sub)
 
                             SelectedOrder = OshkoshOrders.FirstOrDefault
                           End Sub)

End Sub

Posted By: sbelini
Date Posted: 15-Aug-2011 at 12:17pm

Hi Togas,

Since you're doing the binding to the DataGrid in the XAML, you will need to use a CollectionViewSource. There you can set the sort order there and then bind it to your DataGrid.

Take for instance our Silverlight Tour of DevForce sample (in the http://drc.ideablade.com/xwiki/bin/view/Documentation/tour-devforce-silverlight-part1 - DevForce Resource Center ).

Instead of binding the Orders of currentEmployee directly into the DataGrid

<sdk:DataGrid Name="EmployeeOrdersGrid"

ItemsSource="{Binding ElementName=EmployeeDataForm,

Path=CurrentItem.Orders}" />

you'd bind the Orders to the CollectionViewSource, sort it, and bind the CollectionViewSource to the DataGrid

<Grid.Resources>

<CollectionViewSource x:Key="OrdersViewSource" Source="{Binding ElementName=EmployeeDataForm,

Path=CurrentItem.Orders}">

<CollectionViewSource.SortDescriptions>

<scm:SortDescription PropertyName="Freight"/>

</CollectionViewSource.SortDescriptions>

</CollectionViewSource>

</Grid.Resources>

...

<sdk:DataGrid Name="EmployeeOrdersGrid"

ItemsSource="{Binding Source={StaticResource OrdersViewSource}}"

Regards,

Silvio.

Posted By: Togas
Date Posted: 15-Aug-2011 at 12:44pm

Perfect

Thanks Silvio