How to get the CommandParameter value from view to viewModel

Question

This is my view (TypeAheadTextBox.xaml)

    <TextBox x:Name="textBox" Width="300" Text="{Binding SomeText, UpdateSourceTrigger=PropertyChanged}" TextChanged="textBox_TextChanged_1" SelectionChanged="textBox_SelectionChanged">
      <TextBox.InputBindings>                
        <KeyBinding Command="{Binding LeftCtrlKeyPressed, Mode=TwoWay}" Key="Space"  Modifiers="Control" />
        <KeyBinding Key="Down" Command="{Binding TextBoxDownArrow, Mode=TwoWay}" />
      </TextBox.InputBindings>
    </TextBox>

This is my view cs file(TypeAheadTextBox.xmal.cs)

public partial class TypeAheadControl
{
    public TypeAheadControl()
    {
        InitializeComponent();
    }


    private void textBox_TextChanged_1(object sender, TextChangedEventArgs e)
    {
        SetCommandParameter(sender);
    }

    private void textBox_SelectionChanged(object sender, RoutedEventArgs e)
    {
        SetCommandParameter(sender);
    }

    private void SetCommandParameter(object sender)
    {
        TextBox textBox = sender as TextBox;
        if (textBox != null && textBox.Text.Length > 0)
        {
            KeyBinding kb = textBox.InputBindings[0] as KeyBinding;
            if (kb != null)
            {
                string[] words = textBox.Text.Split(new char[] { ' ' });
                if (textBox.CaretIndex == textBox.Text.Length)
                {
                    //return last word
                    kb.CommandParameter = words[words.Length - 1];
                    Console.WriteLine(words[words.Length - 1]);
                }
                else
                {
                    int charCount = 0;
                    foreach (string word in words)
                    {
                        charCount += word.Length;
                        if (charCount >= textBox.CaretIndex)
                        {
                            kb.CommandParameter = word;
                            Console.WriteLine(word);
                            break;
                        }
                    }
                }
            }
        }
    }

}

And this is my ViewModel Class (part of it)

  private DelegateCommand _leftCtrlKeyPressed;

     public ICommand LeftCtrlKeyPressed
    {
        get
        {
            if (_leftCtrlKeyPressed == null)
            {
                _leftCtrlKeyPressed = new DelegateCommand(CtrlKeyDetected);
            }
            return _leftCtrlKeyPressed;  
        }
        set { }
    }

     public void CtrlKeyDetected()
     {

         Console.WriteLine("Test=====>>" + CurrentWord);
     }

My Problem :

Now I want to access the Textbox keybinding command parameter value in my viewModel deligateCommand Action

CtrlKeyDetected().

Can somebody please tell me how can I achieve that.

What the program actually do ?

Suppose you have write down some text in the text box and placed your cursor over a word and my target is to get the current word under the current position of the cursor. As soon as the user press ctrl+space key i want to get the value in the command binding method.

@Default: You are right. Generic version of delegate command solve my issue. — ifti24
– ifti24, Commented Sep 26, 2014 at 9:07

default · Accepted Answer · 2014-09-25 07:42:14Z

1

If you're using for instance PRISMs DelegateCommand there should be a generic version as well. The generic version accepts command parameters, so the following should work:

private DelegateCommand<string> _leftCtrlKeyPressed;

public ICommand LeftCtrlKeyPressed
{
    get
    {
        if (_leftCtrlKeyPressed == null)
        {
            _leftCtrlKeyPressed = new DelegateCommand<string>(CtrlKeyDetected);
        }
        return _leftCtrlKeyPressed;  
    }
    set { }
}

 public void CtrlKeyDetected(string parameter)
 {

     Console.WriteLine("Test=====>>" + parameter);
 }

answered Sep 25, 2014 at 7:42

default

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