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Error "Parent grid cannot be null" when expanding child

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GridView

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Peter Meinl asked on 03 Feb 2010, 05:31 PM

I am trying to display hierarchical data from a WCF Data Service.
This works fine with the WPF grid. With the Silverlight version I have the following problem.

This Grid displays the Parent Data with fine.
When clicking on the + to expand a child grid a ge the error
System.ArgumentNullException: Parent grid cannot be null
Parameter name: parentGridViewDataControlPeer
   at Telerik.Windows.Controls.GridView.Automation.GridViewCellAutomationPeer..ctor(GridViewCell owner, GridViewDataControlAutomationPeer parentGridViewDataControlPeer)
   at Telerik.Windows.Controls.GridView.GridViewCell.OnCreateAutomationPeer()
   at System.Windows.UIElement.GetOrCreateAutomationPeer()
   at System.Windows.UIElement.OnCreateAutomationPeer(IntPtr nativeTarget, IntPtr& returnAP)

    
            Imports RadControlsSilverlightApplication1.ServiceReference1  
        
            Imports System.Data.Services.Client  
        
            Imports Telerik.Windows.Controls  
        
            Partial Public Class MainPage  
        
                Inherits UserControl  
        
                Dim ctx As New NorthwindEntities(New Uri("http://localhost:11702/WebDataService1.svc/"))  
        
                Public Sub New()  
        
                    InitializeComponent()  
        
                    Dim td As New GridViewTableDefinition()  
        
                    td.Relation = New Telerik.Windows.Data.PropertyRelation("Orders")  
        
                    radGridView.ChildTableDefinitions.Add(td)  
        
                End Sub 
        
                Private Sub ShowButton_Click(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles ShowButton.Click  
        
                    ShowData()  
        
                End Sub 
        
                Private Sub ShowData()  
        
                    Dim query As DataServiceQuery(Of Customers) = ctx.Customers.Expand("Orders")  
        
                    query.BeginExecute(AddressOf RequestCompleted, query)  
        
                End Sub 
        
                Private Sub RequestCompleted(ByVal asyncResult As IAsyncResult)  
        
                    Dim query As DataServiceQuery(Of Customers) = TryCast(asyncResult.AsyncState, DataServiceQuery(Of Customers))  
        
                    Dim customers = query.EndExecute(asyncResult).ToList()  
        
                    Me.radGridView.ItemsSource = customers  
        
                End Sub 
        
            End Class

    
            <UserControl xmlns:telerik="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls"  xmlns:telerikGridView="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.GridView"  x:Class="RadControlsSilverlightApplication1.MainPage" 
        
                xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"   
        
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        
                xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"   
        
                mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480">  
        
                 <Grid x:Name="LayoutRoot">  
        
                    <StackPanel> 
        
                     <telerik:RadButton x:Name="ShowButton" Content="Show"> </telerik:RadButton> 
        
                     <telerikGridView:RadGridView x:Name="radGridView"/>  
        
                    </StackPanel> 
        
              </Grid> 
        
            </UserControl>

Error &quot;Parent grid cannot be null&quot; when expanding child

3 Answers, 1 is accepted

Error "Parent grid cannot be null" when expanding child