PropertyChanged event firing twice?

Curtmantle posted on Friday, January 16, 2009

I am trapping the PropertyChanged event of my business classes on my WinForms and have noticed that the event handler is called twice when a property is changed.

eg:

BusinessClass bo = BusinessClass.NewBusinessClass();
bo.PropertyChanged += PropertyChangedEventHandler(Base_PropertyChanged);

private void Base_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    //will display twice when a BO property is changed
    MessageBox.Show("Huh?");
}

The only thing that springs to mind is that I am storing the Business Object as a member variable, and setting the BindingSource's datasource to that member variable, but I don't really see why that should make a difference as it's a reference.

Is there a technical reason for this that I am unaware of? The business class is only firing the event once, so it appears to be Binding related. I am using CSLA 3.0.4.0.

Thanks

Curtmantle replied on Friday, January 16, 2009

I have found the reason for this, and I'm happy to say it's not a problem with CSLA, but the idiot who programmed the form used as a base for all the forms in my app. That idiot being me!

I was inadvertently setting the PropertyChanged handler twice: ie - bo.PropertyChanged += etc...

Doh!