Question

I am working with Attached Property in MVVM and encountered a interesting problem.

I am making an attached property called WorkType to a button as follow:

public static DependencyProperty WorkTypeProperty = DependencyProperty.RegisterAttached("WorkType",
           typeof(WorkTypeEnum),
           typeof(MyControl),
           new PropertyMetadata(WorkTypeChanged));

public static void SetWorkType(DependencyObject target, WorkTypeEnum value)
{
    target.SetValue(WorkTypeProperty, value);
}

public static WorkTypeEnum GetWorkType(DependencyObject target)
{
    return (WorkTypeEnum)target.GetValue(WorkTypeProperty);
}

public static void WorkTypeClick(object sender, MouseButtonEventArgs e)
{
    var control = (Control)sender;
    WorkTypeEnume workType = (WorkTypeEnum)control.GetValue(WorkTypeProperty);
    (Instance of MyControl).DoWork(workType); ??? <--How to know the instance of MyControl?
}

private static void WorkTypeChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)
{
    var control = target as Control;
    if (control != null)
    {
        if ((e.NewValue != null) && (e.OldValue == null))
        {
            control.MouseDown += WorkTypeClick;
        }
        else if ((e.NewValue == null) && (e.OldValue != null))
        {
            control.MouseDown -= WorkTypeClick;
        }
    }
}

I am wondering how could I bind the WorkType to a button so that it will execute the instance of MyControl.DoWork(WorkTypeEnum workType)?

Is there anyway I can assign the instance of MyControl to the button?

Thank you so much!

Answer 1

You are using an attached property, there is no instance of MyControl. If you are looking to pass parameters when a button is pressed, it might be worth look at using Commands.