How to access the texblocks in a listbox?

Question

Hi All,
I have a listbox which I can successfully update with the data but now I want to access two specific textblocks which I want to  collapse and make the other visible.
<ListBox Grid.Row="3" Grid.Column="0" Grid.ColumnSpan="3" HorizontalAlignment="Stretch" Name="myPM_MListBox" Margin="-5,0,-5,0" SelectionChanged="myPMListBox_SelectionChanged">
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch"></Setter>
</Style>
</ListBox.ItemContainerStyle>
<ListBox.ItemTemplate>
<DataTemplate>
<Grid Margin="0,0,0,0" HorizontalAlignment="Stretch">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="150" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Border Grid.Row="0" Grid.Column="0" Margin="5,0,0,0" Background="#FF009E49" BorderThickness="1" BorderBrush="#FF505050">
<TextBlock Margin="5,5,5,5" Text="Message Date" FontSize="16" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="#FFFFFFFF" FontWeight="Normal"/>
</Border>
<Border Grid.Row="0" Grid.Column="1" Margin="0,0,5,0" Background="#FFEFEFEF" BorderThickness="1" BorderBrush="#FF505050">
<TextBlock Margin="5,5,5,5" x:Name="PMMessagePubDate" Text="{Binding shdMsgPublishTime}" FontSize="16" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="#FF000000" FontWeight="Normal"/>
</Border>
<Border Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" Margin="5,0,5,0" Background="#FFEFEFEF" BorderThickness="1,1,1,0" BorderBrush="#FF505050">
<TextBlock Margin="5,5,5,5" x:Name="PM_MLimitedBody" Text="{Binding shdMessageText}" FontSize="16" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="#FF000000" FontWeight="Normal"/>
</Border>
<Border Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2" Margin="5,0,5,0" Background="#FFEFEFEF" BorderThickness="1,0,1,1" BorderBrush="#FF505050">
<TextBlock Margin="5,5,5,5" x:Name="PM_MFullBody" Text="Show more..." FontSize="16" HorizontalAlignment="right" TextWrapping="Wrap" VerticalAlignment="Top" Foreground="Blue" FontWeight="Normal" Tapped="ShowFullBody_Tap"/>
</Border>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I want to hide PM_MLimitedBody textblock and show the PM_MFullBody textblock for the ShowFullBody_Tap event handler I have. But seems like I can't access the Visibility properties of these textblok in my .cs file. is there a way for me to
access these textblock's visibility property in my .cs file?
Thank You!   
mujno

Answer 1

Hi Mujno,
>>I want to hide PM_MLimitedBody textblock and show the PM_MFullBody textblock for the ShowFullBody_Tap event handler I have. But seems like I can't access the Visibility properties of these textblok in my .cs file. is there a way
for me to access these textblock's visibility property in my .cs file?
Yes, as you said, we can not access the textblock controls which are in the DataTemplate by using their names in the .cs file. But we can use the
VisualTreeHelper to help us find these textblock controls.
I have created the following example, in my example the PM_MLimitedBody textblock will be hidden in the ShowFullBody_Tap event, for more information, please try to check it:
private void ShowFullBody_Tap(object sender, TappedRoutedEventArgs e)
TextBlock MyTextBlock = (TextBlock)MyFindListBoxChildByName(this.myPM_MListBox.ContainerFromItem(this.myPM_MListBox.SelectedItem), "PM_MLimitedBody");
MyTextBlock.Visibility = Visibility.Collapsed;
public static DependencyObject MyFindListBoxChildByName(DependencyObject parant, string ControlName)
int count = VisualTreeHelper.GetChildrenCount(parant);
for (int i = 0; i < count; i++)
var MyChild = VisualTreeHelper.GetChild(parant, i);
if (MyChild is FrameworkElement && ((FrameworkElement)MyChild).Name == ControlName)
return MyChild;
var FindResult = MyFindListBoxChildByName(MyChild, ControlName);
if (FindResult != null)
return FindResult;
return null;
Best Regards,
Amy Peng
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