WPF Window Return Value

Question

I have a Window which pop-ups another Window. I want the second Window to be able to return an object to the first Window when a button is pressed. How would I do this?

Answer 1

You can expose a property on the second window, so that the first window can retrieve it.

public class Window1 : Window
{
    ...

    private void btnPromptFoo_Click(object sender, RoutedEventArgs e)
    {
        var w = new Window2();
        if (w.ShowDialog() == true)
        {
            string foo = w.Foo;
            ...
        }
    }
}

public class Window2 : Window
{
    ...

    public string Foo
    {
        get { return txtFoo.Text; }
    }

}

Answer 2

If you don't want to expose a property, and you want to make the usage a little more explicit, you can overload ShowDialog:

public DialogResult ShowDialog(out MyObject result)
{
   DialogResult dr = ShowDialog();
   result = (dr == DialogResult.Cancel) 
      ? null 
      : MyObjectInstance;
   return dr;
}