WPF : Creating a Behavior for a TextBox which invokes a command when Enter key is pressed

Goal :  Execute a command when an enter key is pressed ,while focus is in a text-box.  This command can be a command bounded to a Button or any UI element.

Look at following code

Here I am going to create an attached property of ICommand type, which would be applied to TextBoxes. While that property is getting attached to a TextBox, I register an EventHandler for KeyUp event and in that I check for Enter key cod, if it matches I execute attached command property for that object.

/// <summary>

/// EnterKeyCommand Attached Dependency Property

/// </summary>

public static readonly DependencyProperty EnterKeyCommandProperty =

DependencyProperty.RegisterAttached("EnterKeyCommand", typeof(ICommand), typeof(TextBoxBehaviours), new FrameworkPropertyMetadata(null, new PropertyChangedCallback(OnEnterKeyCommandChanged)));

/// <summary>

/// Gets the EnterKeyCommand property. This dependency property 

/// indicates ....

/// </summary>

public static ICommand GetEnterKeyCommand(DependencyObject d)

{

 return (ICommand)d.GetValue(EnterKeyCommandProperty);

}

/// <summary>

/// Sets the EnterKeyCommand property. This dependency property 

/// indicates ....

/// </summary>

public static void SetEnterKeyCommand(DependencyObject d, ICommand value)

{

 d.SetValue(EnterKeyCommandProperty, value);

}

/// <summary>

/// Handles changes to the EnterKeyCommand property.

/// </summary>

private static void OnEnterKeyCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

{

 ICommand oldEnterKeyCommand = (ICommand)e.OldValue;

 ICommand newEnterKeyCommand = (ICommand)d.GetValue(EnterKeyCommandProperty);

 if (d is TextBox )

 {

   (d as TextBox).KeyUp += new KeyEventHandler(TextBoxBehaviours_KeyUp);

 }

}