WPF Binding a ListBox to an enum, displaying the Description Attribute.

Question

Is it possible to use the ObjectDataProvider method to bind a ListBox to an enum, and style it somehow to display the Description attriibute? If so how would one go about doing this...?

Answer 1

If you bind to the Enum, you could probably convert this to the description through an IValueConverter.

See http://stackoverflow.com/questions/1281490/binding-comboboxes-to-enums-in-silverlight for a description on how to accomplish this.

See http://msdn.microsoft.com/en-us/library/system.windows.data.ivalueconverter.aspx for more information.

Answer 2

Yes, it is possible. This will do it. Say we have the enum

public enum MyEnum
{
    [Description("MyEnum1 Description")]
    MyEnum1,
    [Description("MyEnum2 Description")]
    MyEnum2,
    [Description("MyEnum3 Description")]
    MyEnum3
}

Then we can use the ObjectDataProvider as

xmlns:MyEnumerations="clr-namespace:MyEnumerations"

<ObjectDataProvider MethodName="GetValues"
                ObjectType="{x:Type sys:Enum}"
                x:Key="MyEnumValues">
    <ObjectDataProvider.MethodParameters>
        <x:Type TypeName="MyEnumerations:MyEnum" />
    </ObjectDataProvider.MethodParameters>
</ObjectDataProvider>

And for the ListBox we set the ItemsSource to MyEnumValues and apply an ItemTemplate with a Converter.

<ListBox Name="c_myListBox" SelectedIndex="0" Margin="8"
        ItemsSource="{Binding Source={StaticResource MyEnumValues}}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Converter={StaticResource EnumDescriptionConverter}}"/>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

And in the converter we get the description and return it

public class EnumDescriptionConverter : IValueConverter
{
    private string GetEnumDescription(Enum enumObj)
    {
        FieldInfo fieldInfo = enumObj.GetType().GetField(enumObj.ToString());

        object[] attribArray = fieldInfo.GetCustomAttributes(false);

        if (attribArray.Length == 0)
        {
            return enumObj.ToString();
        }
        else
        {
            DescriptionAttribute attrib = attribArray[0] as DescriptionAttribute;
            return attrib.Description;
        }
    }

    object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        MyEnum myEnum = (MyEnum)value;
        string description = GetEnumDescription(myEnum);
        return description;
    }

    object IValueConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return string.Empty;
    }
}

The GetEnumDescription method should probably go somewhere else but you get the idea :)