Code-behind can't find control declared in XAML

Question

After googling for sometime, x:Name should be a solution to my problem.

In my wtfapp.xaml there is a TextBlock that will be created during runtime:

<TextBlock x:Name="wtf" Text="{Binding fTx}"/>

In the code-behind, it should be accessible so I tried to change its Foreground color:

wtf.Foreground = Brushes.DarkGreen;

When I compile, an error shows up:

The name "wtf" does not exist in the current context.

If I'm not mistaken, that means TextBlock "wtf" is not accessible.

How can I resolve the reference?

EDIT:

XAML:

    <DataTemplate x:Key="ItemTemplate_NextAnime_HOVER">
        <Grid Margin="2,0,1,0" Width="82" Height="120" >
            <Image x:Name="NxtAnime_Image" Width="82" Height="120" Stretch="UniformToFill" Panel.ZIndex="0">
                <Image.Source>
                    <BitmapImage UriCachePolicy="Revalidate" UriSource="{Binding rLocalPic}"/>
                </Image.Source>
            </Image>
            <Grid Panel.ZIndex="1" >
                <Border Background="#7F000000" Panel.ZIndex="0" x:Name="brd">
                    <Popup IsOpen="True" StaysOpen="True" PlacementTarget="{Binding ElementName=brd}" Placement="Top">
                        <StackPanel Background="#FFC54B4B" Orientation="Horizontal" Height="334" Width="430">
                            <Image Width="213" Height="326" Stretch="UniformToFill" Margin="4,4,4,6" Source="{Binding LocalPic}"/>
                            <StackPanel Orientation="Vertical" Margin="4,4,4,4" Name="are">
                                <TextBlock Margin="0,0,0,10" Text="{Binding Title}" FontSize="22" Foreground="White" TextWrapping="Wrap" MaxWidth="200" FontWeight="Bold"/>
                                <StackPanel Orientation="Horizontal">
                                    <TextBlock Text="Relation: " FontSize="20" Foreground="White"/>
                                    <TextBlock x:Name="wtf" Text="{Binding Type}" FontSize="20" Foreground="White"/>
                                </StackPanel>
                            </StackPanel>
                        </StackPanel>
                    </Popup>
                </Border>
            </Grid>
        </Grid>
    </DataTemplate>

This is a DataTemplate for ListBoxItem.

@SLaks it doesn't work :( you may want to see this:http://stackoverflow.com/questions/13569782/how-to-access-control-in-code-behind-that-was-created-in-xaml — Wahyu, Jan 03 '16 at 14:47
That's because in that example it's a user-defined control. In your case you want Name, not x:Name. — Jeff, Jan 03 '16 at 14:50
can you provide the xaml code where your textblock is defined, so we can see the context? — Alex Butenko, Jan 03 '16 at 14:51
is that enough? pasting the whole xaml would be a problem but i will do if it neccesary — Wahyu, Jan 03 '16 at 15:06
You're inside a Popup so at the page level those fields won't be in scope. — Jeff, Jan 03 '16 at 15:08
@Jeff Oh i see, then is there any alternative? Or is there a way so it would be accessible? Sorry, im very new to wpf :D — Wahyu, Jan 03 '16 at 15:09
It depends what you're trying to do. How are you using the popup? — Jeff, Jan 03 '16 at 15:15
I copied that XAML into a UserControl and managed to get the `wft` element just fine. — Cameron MacFarland, Jan 03 '16 at 15:15
@CameronMacFarland Ah, you're right. Sorry for the red herring. In that case if it's not in a template I have no idea. Possibly a build issue. — Jeff, Jan 03 '16 at 15:22
To get a `TextBlock` inside an template and change it's properties in code you should use `FrameworkTemplate.FindName` Method. Check this answer: http://stackoverflow.com/questions/34117944/listbox-items-return-string-when-datatemplate-is-button — Salah Akbari, Jan 03 '16 at 15:24
Yes, as @user2946329 pointed out you'll need to find the control since it's part of a template. My original assertion was incorrect. — Jeff, Jan 03 '16 at 15:26

score 3 · Accepted Answer · edited May 23 '17 at 11:44

It's difficult to get an element from a template, as a template is like a factory, and will generate multiple instances.

As suggested by user2946329 in the comments, ListBox items return string, when DataTemplate is Button answers how to get the element, but there might be another way to do what you want.

For example, if you want to change the color of the wtf element you can do so with a trigger.

<DataTemplate.Triggers> <DataTrigger Binding="{Binding ...}" Value="False"> <Setter TargetName="wtf" Property="Foreground" Value="DarkGreen"/> </DataTrigger> </DataTemplate.Triggers>

Code-behind can't find control declared in XAML

1 Answers1