Bind ICommand to enter pressed - mvvm-light

Question

So i have a windows 8 application with a basic view:
Example:
<TextBox Text="{Binding UserName}"/>
<PasswordBox Text="{Binding Password}"/>
<Button Content="Sign In" Command="{Binding Login}"/>
And a View Model with the ICommand implemented.
public class LoginViewModel : ViewModelBase
{
public ICommand Login { get; set; }
//Other properties
public LoginViewModel()
{
Login = ExecuteLogin;
}
public void ExecuteLogin()
{
//Logic
}
}
It all works fine. But now I want to trigger the ICommand when the user presses enter in the password box, just for a better User Experience. Anybody has any idea how to do it?

Answer 1

Yes, what you need is this class:
namespace SL
{
public sealed class EnterKeyDown
{
#region Properties
#region Command
/// <summary>
/// GetCommand
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public static ICommand GetCommand(DependencyObject obj)
{
return (ICommand)obj.GetValue(CommandProperty);
}
/// <summary>
/// SetCommand
/// </summary>
/// <param name="obj"></param>
/// <param name="value"></param>
public static void SetCommand(DependencyObject obj, ICommand value)
{
obj.SetValue(CommandProperty, value);
}
/// <summary>
/// DependencyProperty CommandProperty
/// </summary>
public static readonly DependencyProperty CommandProperty =
DependencyProperty.RegisterAttached("Command", typeof(ICommand), typeof(EnterKeyDown), new PropertyMetadata(null, OnCommandChanged));
#endregion Command
#region CommandParameter
/// <summary>
/// GetCommandParameter
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public static object GetCommandParameter(DependencyObject obj)
{
return (object)obj.GetValue(CommandParameterProperty);
}
/// <summary>
/// SetCommandParameter
/// </summary>
/// <param name="obj"></param>
/// <param name="value"></param>
public static void SetCommandParameter(DependencyObject obj, object value)
{
obj.SetValue(CommandParameterProperty, value);
}
/// <summary>
/// DependencyProperty CommandParameterProperty
/// </summary>
public static readonly DependencyProperty CommandParameterProperty =
DependencyProperty.RegisterAttached("CommandParameter", typeof(object), typeof(EnterKeyDown), new PropertyMetadata(null, OnCommandParameterChanged));
#endregion CommandParameter
#region HasCommandParameter
private static bool GetHasCommandParameter(DependencyObject obj)
{
return (bool)obj.GetValue(HasCommandParameterProperty);
}
private static void SetHasCommandParameter(DependencyObject obj, bool value)
{
obj.SetValue(HasCommandParameterProperty, value);
}
private static readonly DependencyProperty HasCommandParameterProperty =
DependencyProperty.RegisterAttached("HasCommandParameter", typeof(bool), typeof(EnterKeyDown), new PropertyMetadata(false));
#endregion HasCommandParameter
#endregion Propreties
#region Event Handling
private static void OnCommandParameterChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
SetHasCommandParameter(o, true);
}
private static void OnCommandChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
FrameworkElement element = o as FrameworkElement;
if (element != null)
{
if (e.NewValue == null)
{
element.KeyUp -= FrameworkElementKeyUp;
}
else if (e.OldValue == null)
{
element.KeyUp += FrameworkElementKeyUp;
}
}
}
private static void FrameworkElementKeyUp(object sender, KeyRoutedEventArgs e)
{
if (e.Key == VirtualKey.Enter)
{
var o = sender as DependencyObject;
var command = GetCommand(sender as DependencyObject);
var element = e.OriginalSource as FrameworkElement;
if (element != null)
{
// If the command argument has been explicitly set (even to NULL)
if (GetHasCommandParameter(o))
{
var commandParameter = GetCommandParameter(o);
// Execute the command
if (command.CanExecute(commandParameter))
{
command.Execute(commandParameter);
}
}
else if (command.CanExecute(element.DataContext))
{
command.Execute(element.DataContext);
}
}
}
}
#endregion
}
}
XAML namespace:
xmlns:sl="clr-namespace:SL;"
XAML code:
<TextBox sl:EnterKeyDown.Command="{Binding SearchClickCommand}"
Text="{Binding Input, Mode=TwoWay,
NotifyOnValidationError=True, ValidatesOnDataErrors=True,
ValidatesOnExceptions=True, ValidatesOnNotifyDataErrors=True}" />
<Button Content="Search"
Command="{Binding SearchClickCommand}" />