Wpf – Capturing the Enter key in a TextBox

wpf

In my WPF view, I am trying to tie an event to the Enter key as follows:

<TextBox Width="240" VerticalAlignment="Center" Margin="2" Text="{Binding SearchCriteria, Mode=OneWayToSource}">
  <TextBox.InputBindings>
      <KeyBinding Key="Enter" Command="{Binding EnterKeyCommand}"/>
      <KeyBinding Key="Tab" Command="{Binding TabKeyCommand}"/>
  </TextBox.InputBindings>
</TextBox>

This code works and my EnterKeyCommand fires when the users presses the Enter key. However, the problem is that when the event fires, WPF hasn't yet bound the text in the textbox to 'SearchCriteria'. So when my event fires, the contents of 'SearchCriteria' is blank. Is there a simple change I can make in this code so that I can get the contents of the textbox when my EnterKey command fires?

Best Answer

You need to change the UpdateSourceTrigger on your TextBox.Text binding to PropertyChanged. See here.

Related Solutions

C# – How should the ViewModel close the form

I was inspired by Thejuan's answer to write a simpler attached property. No styles, no triggers; instead, you can just do this:

<Window ...
        xmlns:xc="clr-namespace:ExCastle.Wpf"
        xc:DialogCloser.DialogResult="{Binding DialogResult}">

This is almost as clean as if the WPF team had gotten it right and made DialogResult a dependency property in the first place. Just put a bool? DialogResult property on your ViewModel and implement INotifyPropertyChanged, and voilà, your ViewModel can close the Window (and set its DialogResult) just by setting a property. MVVM as it should be.

Here's the code for DialogCloser:

using System.Windows;

namespace ExCastle.Wpf
{
    public static class DialogCloser
    {
        public static readonly DependencyProperty DialogResultProperty =
            DependencyProperty.RegisterAttached(
                "DialogResult",
                typeof(bool?),
                typeof(DialogCloser),
                new PropertyMetadata(DialogResultChanged));

        private static void DialogResultChanged(
            DependencyObject d,
            DependencyPropertyChangedEventArgs e)
        {
            var window = d as Window;
            if (window != null)
                window.DialogResult = e.NewValue as bool?;
        }
        public static void SetDialogResult(Window target, bool? value)
        {
            target.SetValue(DialogResultProperty, value);
        }
    }
}

I've also posted this on my blog.

C# – WPF: A TextBox that has an event that fires when the Enter Key is pressed

Have a look at this blog post from a few months back where I attach a 'global' event handler to TextBox.GotFocus to select the text.

Essentially you can handle the KeyUp event in your App class, like this:

protected override void OnStartup(StartupEventArgs e)
{
    EventManager.RegisterClassHandler(typeof(TextBox),
        TextBox.KeyUpEvent,
        new System.Windows.Input.KeyEventHandler(TextBox_KeyUp));

    base.OnStartup(e);
}

private void TextBox_KeyUp(object sender, System.Windows.Input.KeyEventArgs e)
{
    if (e.Key != System.Windows.Input.Key.Enter) return;

    // your event handler here
    e.Handled = true;
    MessageBox.Show("Enter pressed");
}

... and now every TextBox in your application will call the TextBox_KeyUp method as users type into them.

Update

As you've pointed out in your comment, this is only useful if every TextBox needs to execute the same code.

To add an arbitrary event like an Enter keypress, you might be better off looking into Attached Events. I believe this can get you what you want.

Best Answer

Related Solutions

C# – How should the ViewModel close the form

C# – WPF: A TextBox that has an event that fires when the Enter Key is pressed

Related Topic