MVVM Bind enum to Combobox

Question

I'm using caliburn micro framework in a WPF application. I need to bind this enum to a combobox.

Consider following enum in a ViewModel:

public enum MovieType
{
    [Description("Action Movie")]
    Action,
    [Description("Horror Movie")]
    Horror
}

How can I bind this enum to a combobox?
Is it possible to show the enum description insted of enum values in combobox?
Can I implement IvalueConverter for this purpose?

All 3 of these questions are handled in the link I posted above. — Mark Feldman, Nov 05 '15 at 10:39

Tomtom · Answer 1 · 2015-11-05T10:48:40.597

In the resources of your Window/UserControl/? you have to create an ObjectDataProvider like:

<ObjectDataProvider x:Key="MovieDataProvider" MethodName="GetValues" ObjectType="{x:Type namespace:MovieType}">
   <ObjectDataProvider.MethodParameters>
      <x:Type Type="namespace:MovieType"/>
   </ObjectDataProvider.MethodParameters>
</ObjectDataProvider>

To use it as itemssource of your ComboBox you have to do the following:

ItemsSource="{Binding Source={StaticResource MovieDataProvider}}"

If you want to display a custom value you can modify the ItemTemplate of your ComboBox like:

<ComboBox.ItemTemplate>
   <DataTemplate>
      <TextBlock Text="{Binding Converter={converters:MovieDisplayConverter}}"/>
   </DataTemplate>
</ComboBox>

The MovieDisplayConverter can look like the following if you want to return custom values:

internal class MovieDisplayConverter : MarkupExtension, IValueConverter
    {
        private static MovieDisplayConverter converter;

        public MovieDisplayConverter()
        {

        }

        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is MovieType)
            {


                switch ((MovieType)value)
                {
                    case MovieType.Action:
                        return "Action Movie";
                    case MovieType.Horror:
                        return "Horror Movie";
                    default:
                        throw new ArgumentOutOfRangeException("value", value, null);
                }
            }
            return value;
        }

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

        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            return converter ?? (converter = new MovieDisplayConverter());
        }
    }

If you want the description-attribute of your enum-values in the ComboBox replace the convert-method of the above converter with the following:

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is MovieType)
            {
                FieldInfo fieldInfo = value.GetType().GetField(value.ToString());
                if (fieldInfo != null)
                {
                    object[] attributes = fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), true);
                    if (attributes.Length > 0)
                    {
                        return ((DescriptionAttribute)attributes[0]).Description;
                    }
                }
            }
            return value;
        }

MVVM Bind enum to Combobox

1 Answers1