Question

I have a WPF application. I am using MVVM.
I have Person Model which is bound to WPF CreatePerson view.
In CreatePerson view, There is textbox in which I bound Text property to Person.FirstName
Now my default focus to FirstName textbox.
When I hit tab key without doing anything, it does not fire validation, but when i write something then it fires properly.

All validations are set properly.

Now I want when I hit tab key, it should fire validation.

If more clearance is required, please let me know.

Answer 1

the validation is called when any attempt to update the binding source occurs. If you want to fire validation when the events GotFocus occurs, you must update your binding programmatically, i.e. in the event handler of GotFocus you can force the binding

private void textBox1_GotFocus(object sender, RoutedEventArgs e)
{
      BindingExpression binding = BindingOperations.GetBindingExpression(textBox1, TextBox.TextProperty);
 binding.UpdateSource(); 
}