CODEWITHSUNDEEP
c#wpfmvvm
Neha
Neha

Reputation: 184

Command getting null in my Attached property used for converting Event to command

I am using mvvm so i am trying to have less (or possibly no) code in code behind. I want to convert KeyDown event on a TextBox to Command.I am using Interactivity dll my Xaml code is:

  <TextBox Background="White" Name="txtHigh" AcceptsReturn="False" Height="23" Width="98"  Margin="3" Grid.Column="3" Text="{Binding SelectionHigh, Mode=TwoWay,Converter={StaticResource formatCell}}">
                    <i:Interaction.Triggers>
                        <i:EventTrigger EventName="KeyDown">
                            <commands:EventToCommand Command="{Binding  HighValueChangedCmd}" ></commands:EventToCommand>
                        </i:EventTrigger>
                    </i:Interaction.Triggers>


and the code for converting EventToCommand is:

  public class EventToCommand : TriggerAction<FrameworkElement>
{
    public ICommand Command
    {
        get { return (ICommand)GetValue(CommandProperty); }
        set { SetValue(CommandProperty, value); }
    }

    public static readonly DependencyProperty CommandProperty =
        DependencyProperty.Register("Command", typeof(ICommand), typeof(EventToCommand), new UIPropertyMetadata(null));


    public object CommandParameter
    {
        get { return (object)GetValue(CommandParameterProperty); }
        set { SetValue(CommandParameterProperty, value); }
    }

    // Using a DependencyProperty as the backing store for CommandParameter.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty CommandParameterProperty =
        DependencyProperty.Register("CommandParameter", typeof(object), typeof(EventToCommand), new UIPropertyMetadata(null));

    protected override void Invoke(object parameter)
    {
        if (Command == null) return;
        if (Command is RoutedCommand)
        {
            var rc = Command as RoutedCommand;
            if (rc.CanExecute(CommandParameter, base.AssociatedObject))
            {
                rc.Execute(CommandParameter, base.AssociatedObject);
            }
        }
        else
        {
            if (Command.CanExecute(CommandParameter))
                Command.Execute(CommandParameter);
        }
    }

}

problem is in my Invoke method I am Getting Command=null..Am not getting why so? and I want to excecute logic in ExecuteCommand method only if the pressed key in enter or tab. In code behind we can do this by using KeyEventArgs.

               KeyEventArgs e;        
               if (e.Key == Key.Enter || e.Key == Key.Tab)
              //logic

how can I achieve this in ExecuteCommand method???

Upvotes: 3

Views: 181

Answers (1)

Den
Den

Reputation: 380

Maybe you should try an alternative way, without implementing Interaction and EventToCommand.

<TextBox Background="White" Name="txtHigh" AcceptsReturn="False" Height="23" Width="98"  Margin="3" Grid.Column="3" Text="{Binding SelectionHigh, Mode=TwoWay,Converter={StaticResource formatCell}}">
 <TextBox.InputBindings>
        <KeyBinding Key="Enter"  Command="{Binding DataContext.HighValueChangedCmd, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Grid}}}" />
        <KeyBinding Key="Tab"  Command="{Binding DataContext.HighValueChangedCmd, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Grid}}}" />
 </TextBox.InputBindings>
</TextBox>

Upvotes: 2

Related Questions