Question

I am using .NET’s IIdentity and IPrincipal objects for role based security, and I am at the step of modifying controls shown based on roles the current user has.

My question is what the recommended method is for enabling/disabling fields in a WPF window – showing/hiding fields dependent on IIdentity.IsInRole type calls.

Can this be done in XAML, or do I have to abstract this into code with what I think is a bit messy in the code behind;

this.txtUserName.IsReadOnly = !MyPrincipal.CurrentPrincipal.IsInRole("Administrator");
this.mnuCreateUser.Visibility = MyPrincipal.CurrentPrincipal.IsInRole("Administrator");
 ? Visibility.Hidden : Visibility.Visible;

(Note; my code checks roles when executing functions, what I am looking to do is modifying the GUI dependent on the roles, so users do not see/see readonly elements that they do not have access to)

Answer 1

Although previous answer will work, to me it looks little ugly to detect visibility in logic objects. I would use converter for that…

<Control Visibility={Binding Path=CurrentPrincipal, Converter={StaticResource RoleToVisibilityConverter}, ConverterParameter=Administrator}/>

And then the converter itself

public class RoleToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var principal = value as Principal;
        if(principal != null) {
            return principal.IsInRole((string)parameter) ? Visibility.Visible : Visibility.Collapsed;
        }

        return null;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
         throw new NotImplementedException();
    }
}