Null exception in UI for Silverlight

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Null exception

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Window

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Artur asked on 07 Jul 2010, 10:59 AM

Hi,

I'm trying to make one custom controller that extends the RadWindow. This controller will have 2 different zones: 1 is the content and the second one footer.
So, to do this, i tried to change the dataTemplate of the content.

    
             <telerik:RadWindow.Resources> 
        
                    <ResourceDictionary>        
        
                        <DataTemplate x:Key="ChangedTemplate"> 
        
                            <Grid> 
        
                                <Grid.RowDefinitions> 
        
                                    <RowDefinition Height="*"/> 
        
                                    <RowDefinition Height="60"/> 
        
                                </Grid.RowDefinitions> 
        
                            <ContentPresenter Grid.Row="0" Content="{Binding Content, RelativeSource={RelativeSource TemplatedParent}}"/> 
        
                                <Button Grid.Row="1" Content="ola"/> 
        
                            </Grid> 
        
                        </DataTemplate> 
        
                        <Style TargetType="local:Dialog"> 
        
                            <Setter Property="ContentTemplate" Value="{StaticResource ChangedTemplate}"/> 
        
                    </Style> 
        
                    </ResourceDictionary> 
        
                </telerik:RadWindow.Resources>

The code above is the just with the content with one button (marking the area of the footer).

Then in mainpage i call this dialog and add one button to the content:

    
            <my3:Dialog x:Name="xdialog" BorderBackground="#FF121010" 
        
                                Background="Lime" BorderBrush="Blue" BorderThickness="1" 
        
                                WindowStartupLocation="CenterScreen" Opacity="10" Header="This is popup" 
        
                            DialogResult="True"> 
        
                        <StackPanel> 
        
                             <TelerikControl:RadButton x:Name="buttontoDisable" Height="50" Width="50" Content="TryIt"/> 
        
                        </StackPanel> 
        
                    </my3:Dialog>

The strange thing (at least for me!!) is when in the code-behind of the mainWindow (c#) if i try to call the "buttontoDisable" (say for example disable it), gives to me a "System.NullReferenceException".

What i'm doing wrong here?

4 Answers, 1 is accepted

Accepted

answered on 12 Jul 2010, 03:03 PM

Hello David,

Thank you for contacting us!

Defining a window in the xaml (i.e. not as a root tag) is not a good approach and we don't support it because it might lead to unexpected behavior. The x:names of the buttons you want to find are defined in different namecope - that's why they couldn't be resolved in the InitializeComponent method. You can get them from the namescope of your custom window. You can use FindName method of the window, for example:

this.xdialog.FindName("buttonOfContainer") as Button;

You can work around this approach with initializing the objects you use in your custom dialog, so you can call them through your custom window, for example.
If you want your footer to participate in the namescope of your custom window, you should edit the ControlTemplate of the window and add a new ControlPresenter for the footer.

I hope this information helps. I will be glad to assist you further.

Sincerely yours,
George
the Telerik team

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Accepted

answered on 14 Jul 2010, 04:20 PM

window.zip

Hello Artur,

Thank you for getting back to me.

First, you need to create two dependency properties Footer and FooterTemplate in your custom window control, same as Content and ContentTemplate properties. Then, apply the attached theme to your control.

I hope this helps. I will be glad to assist you further.

Sincerely yours,
George
the Telerik team