WP8：LongListMultiSelector点击项目触发MVVM

Question

Another question concerning the LongListMultiSelector (Windows Phone 8 Toolkit). I want to start a command when tapping on a single item in the LongListMultiSelector.

XAML

  <local:LongListMultiSelector
                    x:Name="FileList"
                    ItemsSource ="{Binding CurrentFileList}"
                    EnforceIsSelectionEnabled="{Binding IsInSelectionMode}" 
                    toolkit:TiltEffect.IsTiltEnabled="True" 
                    IsSelectionEnabled="True" 
                    ItemContainerStyle="{StaticResource FileBrowserLongListMultiSelectorStyle}" 
                    SelectedFiles="{Binding SelectedFiles}">
                    <local:LongListMultiSelector.ItemTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal" Margin="0,0,0,20">
                                <Rectangle Width="80" Height="80" Fill="{StaticResource BoxCryptorGreenBrush}"/>
                                <StackPanel Margin="10,0">
                                    <TextBlock Text="{Binding Name}" Style="{StaticResource PhoneTextLargeStyle}"/>
                                    <TextBlock Text="{Binding Size}" Style="{StaticResource PhoneTextSmallStyle}"/>
                                </StackPanel>                
                                <i:Interaction.Triggers>
                                    <i:EventTrigger EventName="Tap">
                                        <i:InvokeCommandAction Command="{Binding TapOnFileCommand}" CommandParameter="{Binding}"/>
                                    </i:EventTrigger>
                                </i:Interaction.Triggers>     
                            </StackPanel>
                        </DataTemplate>
                    </local:LongListMultiSelector.ItemTemplate>  
                </local:LongListMultiSelector>

and in my ViewModel:

FileBrowserViewModel

// command
public RelayCommand<File> TapOnFileCommand { get; private set; }

// constructor
public FileBrowserViewModel()
{
    TapOnFileCommand = new RelayCommand<File>(
            TapOnFile,
            (f) => true);
}

// method
private void TapOnFile(File file)
{
   if (file.IsFolder)
   {
        _currentFileList = file.Children;
   }
}

Now the TapOnFileCommand is never executed. IntelliSense even finds the command from the XAML file. What am I missing? I'm using Mvvm Light and I would prefer not to write (to much) code behind.

Answer 1

Here's my solution:

I had to move the TapOnFileCommand in a FileViewModel (elements inside the list). The DataContext inside of the is the single item itself. Output gave the relevant hints.