MVVM捕获文本框粘贴事件

Question

I have tried to transform this this (from old application) to MVVM pattern but I don't see how I will do it.

textBoxLoader.AddHandler(CommandManager.ExecutedEvent, new RoutedEventHandler(PasteFunction), true);

    private void PasteFunction(object sender, RoutedEventArgs e)
        {       
            if ((e as ExecutedRoutedEventArgs).Command == ApplicationCommands.Paste)
            {             
                // verify that the textbox handled the paste command

                textBoxLoader.IsEnabled = false;
                List<string[]> MachineList = new List<string[]>();
                List<string> list = new List<string>(Regex.Split(textBoxLoader.Text, Environment.NewLine));
}}

How can I reproduce this and call command from WPF TextBox Paste event ? I can successfully bind Enter Key event , but how do I bind Paste event ?

Below is a code snippet on how I am binding a Icommand in new MVVM ( Enter Key listener )

<UserControl.InputBindings>
        <KeyBinding Key="Enter" Command="{Binding ClickCommand}" CommandParameter="{Binding Text, ElementName=textBoxLoader}"/>
    </UserControl.InputBindings>

Answer 1

In view :

<TextBox Text="{Binding Text, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="120" Height="200"/>

In view model :

class MainWindowViewModel : BindableBase
{
    private string text;

    public string Text
    {
        get { return text; }
        set { SetProperty(ref text, value); }
    }
}

In this way, when you paste the text or press Ctrl+V the Text value is updated and PropertyChanged event is raised. Thus you can identify the pasted text into textbox.

If you want to identify Ctrl+V for some special reason, try this :

void AssociatedObject_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (Keyboard.Modifiers == ModifierKeys.Control && e.Key == Key.V)
    {
          // Your action
    }
}

Answer 2

In MVVM the textbox is bound to a property on the VM. Why not simply subscribe to the VM's notify property change ( could be done on the VM itself actually ) and look for a change reported on that bound property.

Once a change notification is sent, do the logic needed.

Example

This working example, wouldn't be used in the real world because the work would be done in the setter of Name , demonstrates how to subscribe to the notify event. When Name is changed the VM catches the change from the event and FullName is computed and the property changed is raised for FullName from the subscription.

public class ExampleVM : INotifyPropertyChanged
{
    private string _Name;

    public string Name
    {
        get { return _Name; }
        set { _Name = value; OnPropertyChanged(); }
    }

    public string FullName { get; set; }

    public ExampleVM()
    {
        this.PropertyChanged += (s, a) =>
        {
            if (a.PropertyName == "Name")
            {
                FullName = $"Mr. {Name}";
                OnPropertyChanged("FullName");
            }
        };
    }

    public event PropertyChangedEventHandler PropertyChanged;

    void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

C# 6 coding is used, but can be rewritten in any other version of C#.