Why WPF button's command's CanExecute method is not called even if I call CommandManager.InvalidateRequerySuggested()?

Question

I\'m facing the same issue reported in these questions:

Button Command CanExecute not called when property changed

How can I force a textbox change to enable

Answer 1

While the "PropertyChanged" events are automatically marshalled, the call to CommandManager.InvalidateRequerySuggested() is not.

So to fix the issue just ensure the call is made on the Dispatcher thread as follows:

    private void DataContext_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        switch (e.PropertyName)
        {
            case "Ready":
                var d = Application.Current.Dispatcher;
                if (d.CheckAccess())
                    CommandManager.InvalidateRequerySuggested();
                else
                    d.BeginInvoke((Action)(() => { CommandManager.InvalidateRequerySuggested(); }));
                break;
        }
    }

Be careful when relying on property changes that are triggered by asynchronous tasks.

I hope this can help some of you in saving some days of work...