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NullReferenceException GridView

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GridView

This is a migrated thread and some comments may be shown as answers.

Mike asked on 09 Jan 2012, 01:49 PM

Hi,

We are currently having issues running our application on Windows 7 tablet PC's. When the grid has data, we get a NullReferenceException. I found it that the exception will not occur when removing a specific column definition from the gridview:

<telerik:GridViewColumn     CellTemplate="{StaticResource StatusButtons}"
                                            IsFilterable="False"
                                            MaxWidth="120"
                                            MinWidth="120"
                                            />

The application works fine on non-touch devices, but on touch devices (Win 7, .Net 3.5) the error occurs. Stopping the "Tablet PC Input" service does not help as mentioned in other threads.

The exception plus stacktrace

2012-01-09 10:09:18,868 FATAL - User Interface : Unhandled Exception

System.NullReferenceException: De objectverwijzing is niet op een exemplaar van een object ingesteld.

bij System.Windows.Automation.Peers.AutomationPeer.EnsureChildren()

bij System.Windows.Automation.Peers.AutomationPeer.UpdateChildren()

bij System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()

bij System.Windows.ContextLayoutManager.fireAutomationEvents()

bij System.Windows.ContextLayoutManager.UpdateLayout()

bij System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg)

bij System.Windows.Media.MediaContext.InvokeOnRenderCallback.DoWork()

bij System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()

bij System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)

bij System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)

bij System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)

bij System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)

The Xaml:

<UserControl x:Class="BrabantWater.UI.Screens.ZInspectionListScreen"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:lex="http://schemas.root-project.org/xaml/presentation"

xmlns:imageFactory="clr-namespace:Sap.Eam.UI.Theme;assembly=CustomTheme_WPF"

xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"

Height="auto" Width="auto">

<UserControl.Resources>

<BooleanToVisibilityConverter x:Key="boolToVisConverter"/>

<DataTemplate x:Key="StatusButtons">

<StackPanel Orientation="Horizontal" Width="110">

<telerik:RadButton Click="RadButtonDelete_Click" MinWidth="50"

IsEnabled="{Binding Path=IsDeletable, Mode=OneWay}">

<Image Source="{Binding Path=DeleteImage, Mode=OneWay}" Width="32"/>

</telerik:RadButton>

<telerik:RadButton Click="RadButtonStatus_Click" MinWidth="50"

IsEnabled="{Binding Path=IsEditable,Mode=OneWay}">

<Image Source="{Binding Path=StatusImage, Mode=OneWay}" Width="32"/>

</telerik:RadButton>

</StackPanel>

</DataTemplate>

</UserControl.Resources>

<Grid x:Name="GridContainer">

<Grid.RowDefinitions>

<RowDefinition Height="auto"/>

<RowDefinition Height="*"/>

</Grid.RowDefinitions>

<StackPanel Grid.Row="0" Orientation="Horizontal" Margin="5,5,5,5" Height="35" HorizontalAlignment="Stretch" VerticalAlignment="Center">

<telerik:RadButton x:Name="ButtonNewInstallation" Content="{lex:LocText Key=Inspection_New_Installation, Dict=InspectionResources, Assembly=Win32Resources}" MinWidth="100" Click="ButtonNewInstallation_Click"/>

<telerik:RadButton x:Name="ButtonNewDamage" Content="{lex:LocText Key=Inspection_New_Defect, Dict=InspectionResources, Assembly=Win32Resources}" Margin="10,0,0,0" MinWidth="100" Click="ButtonNewDamage_Click"/>

</StackPanel>

<telerik:RadGridView x:Name="InspectionGrid"

AlternationCount="2"

AutoGenerateColumns="False"

CanUserFreezeColumns="False"

CanUserReorderColumns="False"

ColumnWidth="*"

EditTriggers="None"

Grid.Row="1"

Margin="5"

MouseDoubleClick="InspectionGrid_MouseDoubleClick"

RowIndicatorVisibility="Collapsed"

SelectionChanged="InspectionGrid_SelectionChanged"

SelectedItem="{Binding Path=CurrentInspection, Mode=TwoWay}"

ShowGroupPanel="false">

<telerik:RadGridView.Columns>

<telerik:GridViewDataColumn UniqueName="DamageCodeDescription"

Header="{lex:LocText Key=Inspection_Space, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=DamageCodeDescription, Mode=OneWay}"/>

<telerik:GridViewDataColumn UniqueName="ItemCodeDescription"

Header="{lex:LocText Key=Inspection_Part, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=ItemCodeDescription, Mode=OneWay}"/>

<telerik:GridViewDataColumn UniqueName="ItemDescription"

Header="{lex:LocText Key=Inspection_Addition, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=ItemDescription, Mode=OneWay}"/>

<telerik:GridViewDataColumn UniqueName="CauseCodeDescription"

Header="{lex:LocText Key=Inspection_Task, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=CauseCodeDescription, Mode=OneWay}" />

<telerik:GridViewDataColumn UniqueName="TaskCodeDescription"

Header="{lex:LocText Key=Inspection_Finding, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=TaskCodeDescription, Mode=OneWay}" />

<telerik:GridViewDataColumn UniqueName="ActivityCodeDescription"

Header="{lex:LocText Key=Inspection_Risk, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=ActivityCodeDescription, Mode=OneWay}" />

<telerik:GridViewImageColumn DataMemberBinding="{Binding Path=AttachmentImage, Mode=OneWay}"

Header="{lex:LocText Key=Inspection_Attachments, Dict=InspectionResources, Assembly=Win32Resources}"

ImageHeight="32"

ImageWidth="32"

IsFilterable="False"

MaxWidth="60"

MinWidth="60"

/>

<telerik:GridViewColumn CellTemplate="{StaticResource StatusButtons}"

IsFilterable="False"

MaxWidth="120"

MinWidth="120"

/>

</telerik:RadGridView.Columns>

</telerik:RadGridView>

</Grid>

</UserControl>

The version of the Telerik WPF components being used: 2010.2.0716.35.

How can we solve this issue?

Kind regards,

Mike

6 Answers, 1 is accepted

answered on 10 Jan 2012, 11:03 AM

Hi Vlad,

We have another screen which is simular, but this screen has not the same issue, but its also using a GridView with a column defined in the UserControl.Resources.. I dont understand why one screen works and the other doesnot work.

<UserControl x:Class="BrabantWater.UI.Screens.ZPrioritairListScreen"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:lex="http://schemas.root-project.org/xaml/presentation"

xmlns:Common="clr-namespace:Sap.Eam.UI.UIControl.Common"

xmlns:imageFactory="clr-namespace:Sap.Eam.UI.Theme;assembly=CustomTheme_WPF"

xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"

Height="auto" Width="auto">

<UserControl.Resources>

<BooleanToVisibilityConverter x:Key="BooleanToVisibility" />

<DataTemplate x:Key="StatusButtons">

<StackPanel Orientation="Horizontal" Width="110">

<telerik:RadButton Click="RadButtonOk_Click"

IsEnabled="{Binding Path=IsEditable, Mode=OneWay}"

Width="50">

<Image Source="{Binding Path=OkImage, Mode=OneWay}" Width="32"/>

</telerik:RadButton>

<telerik:RadButton Click="RadButtonNok_Click"

IsEnabled="{Binding Path=IsEditable, Mode=OneWay}"

Width="50">

<Image Source="{Binding Path=NokImage, Mode=OneWay}" Width="32"/>

</telerik:RadButton>

</StackPanel>

</DataTemplate>

<DataTemplate x:Key="GroupHeader">

<Grid Height="50" VerticalAlignment="Center">

<Grid.ColumnDefinitions>

<ColumnDefinition Width="288" />

<ColumnDefinition />

</Grid.ColumnDefinitions>

<TextBlock VerticalAlignment="Center" Text="{Binding Group.Key, Mode=OneWay}" />

<telerik:RadButton Click="RadButtonGroup_Click" Tag="{Binding Group.Key, Mode=OneWay}"

IsEnabled="{Binding Path=IsEditable, Mode=OneWay}" Height="40" Width="50" Grid.Column="1">

<Image Source="pack://application:,,,/CustomTheme_WPF;component/Common/Images/ok48.png"/>

</telerik:RadButton>

</Grid>

</DataTemplate>

</UserControl.Resources>

<Grid x:Name="GridContainer">

<telerik:RadGridView x:Name="PrioritairGrid"

AutoExpandGroups="True"

AutoGenerateColumns="false"

ColumnWidth="*"

EditTriggers="None"

CanUserFreezeColumns="False"

GroupHeaderTemplate="{StaticResource GroupHeader}"

HorizontalContentAlignment="Stretch"

MouseDoubleClick="PrioritairGrid_MouseDoubleClick"

RowIndicatorVisibility="Collapsed"

SelectedItem="{Binding Path=CurrentPrioritair, Mode=TwoWay}"

SelectionChanged="PrioritairGrid_SelectionChanged"

ShowColumnHeaders="False"

ShowGroupPanel="false"

>

<telerik:RadGridView.Columns>

<telerik:GridViewDataColumn DataMemberBinding="{Binding Path=ItemCode, Mode=OneWay}" IsVisible="False" IsGroupable="True"/>

<telerik:GridViewDataColumn DataMemberBinding="{Binding Path=ItemCodeDescription, Mode=OneWay}" IsGroupable="True" IsVisible="False" />

<telerik:GridViewDataColumn DataMemberBinding="{Binding Path=DamageCodeDescription, Mode=OneWay}" IsGroupable="False" MinWidth="250" />

<telerik:GridViewColumn CellTemplate="{StaticResource StatusButtons}" MaxWidth="125"/>

<telerik:GridViewDataColumn DataMemberBinding="{Binding Path=TaskCodeDescription, Mode=OneWay}" IsGroupable="False" MinWidth="100" />

<telerik:GridViewDataColumn DataMemberBinding="{Binding Path=ActivityCodeDescription, Mode=OneWay}" IsGroupable="False" MinWidth="100" />

</telerik:RadGridView.Columns>

</telerik:RadGridView>

</Grid>

</UserControl>

answered on 11 Jan 2012, 11:13 AM

Ticket-499415-RadGridView.zip

Hello,

We were able to reproduce the described issue with version 2010.2.716.35. Actually, our Q2 SP1 2010 (2010.2.812.35) version includes the fix and we would suggest you to upgrade to it. I have attached a project with updated binaries so you can test it on your side.

Greetings,
Vera
the Telerik team

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