I answered a question a week or so ago, and was unable to point to an example of using an IValueConverter
to select a View. I said I would publish something, so here it is.
One of the things a value converter can be used for is set the View
. A good choice for the property to bind to is the ViewModel
. The value converter can then set the View
depending on the type of the ViewModel
:
class ViewModelViewValueConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
if (value is UserControlViewModel1)
return new View1();
else if (value is UserControlViewModel2)
return new View2();
return null;
}
public object ConvertBack(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
The application I have created to show this concept is really basic. Many of the class are empty, including the UserControl
ViewModel
classes, and the each of the UserControls
only contain some text and no extra code behind. The ViewModel
for the main form contains only two DelegateCommand
properties to change the ViewModel
in the ViewModel
property to one of the two classes. If you are familiar with binding in WPF, you will see that the MainViewModel
inherits from INotifyPropertyChanged
since I need to be able to inform the View
when the ViewModel
property is changed. The only other significant part of the solution is the binding. I used a ContentControl
in the ViewModel
and bind to its Content
property:
<ContentControl Content="{Binding ViewModel,
Converter={StaticResource ValueConverter}}"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch" />