Using WPF Validation rules and the disabling of a 'Save' button

Question

I have a page where a few textboxes cannot be empty before clicking a Save button.

Answer 1

Because it's still missing, here is an adaption of Developer's answer in case the link ever goes away:

XAML:

CodeBehind/C#:

private int _numberOfValidationErrors;
public bool HasNoValidationErrors => _numberOfValidationErrors = 0;

private void handleValidationError(object sender, ValidationErrorEventArgs e)
{
    if (e.Action == ValidationErrorEventAction.Added)
        _numberOfValidationErrors++;
    else
        _numberOfValidationErrors--;
}