how to access a control within Data Template from code behind? [closed]

Question

I have a MediaElement within the DataTemplate but I am unable to access it from the code behind.

I am posting XAML code below:

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="605*"/>
        <ColumnDefinition Width="151*"/>
    </Grid.ColumnDefinitions>
    <GroupBox Header="My Videos" Height="177" VerticalAlignment="Top" Margin="5,320,5,0" Grid.ColumnSpan="2">
        <ListBox x:Name="VideoList" ItemsSource="{Binding Videos }" Width="auto" Height=" auto" Margin="0,0,0,0" Grid.ColumnSpan="2" >
            <DataTemplate x:Name="DTVideos">
                <ListBoxItem Name="lbivid1" BorderThickness="2"  Width="240" Selected="lbivid_Selected" >
                    <MediaElement Name="vidList" Height="150" Width="150" Source="{Binding SourceUri}" Position="00:00:05" LoadedBehavior="Pause" ScrubbingEnabled="True"/>
                </ListBoxItem>
            </DataTemplate>
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <StackPanel Orientation="Horizontal" Margin="0,0,0,0"/>
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
        </ListBox>
    </GroupBox>     
    <GroupBox Header="Preview" Height="320" Width="400" VerticalAlignment="Top" DockPanel.Dock="Left">
        <MediaElement x:Name="videoPreview" HorizontalAlignment="Left" Height="300" VerticalAlignment="Top" Width="388"/>
    </GroupBox>
</Grid>

Code behind:

 private void lbivid_Selected(object sender, RoutedEventArgs e)
 {   
    imagePreview.Visibility = Visibility.Hidden;   
    string urlStr = (VidList.Source).ToString();          
    Uri temp = new Uri(UrlStr);
    videoPreview.Source = temp;                         
 }   

Can anyone of you please tell me how can it be done?

Answer 1

You should be able to access your control using the FrameworkTemplate.FindName method... first, get the ContentPresenter from one of the ListBoxItems:

ContentPresenter contentPresenter = FindVisualChild<ContentPresenter>(yourListBoxItem);

Then get the DataTemplate from the ContentPresenter:

DataTemplate yourDataTemplate = contentPresenter.ContentTemplate;

Then get the MediaElement from the DataTemplate:

MediaElement yourMediaElement = yourDataTemplate.FindName("vidList", contentPresenter) 
as MediaElement;
if (yourMediaElement != null)
{
    // Do something with yourMediaElement here
}

Please see the FrameworkTemplate.FindName Method page on MSDN for more information.