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Binding Enum with DescriptionAttribute in WPF

Binding an enumeration to a ComboBox can be done in several ways. In most cases you don't want to display the value itself, but a more user friendly description. One common approach is to use the DescriptionAttribute on the Enum values to supply a description for each value. This is all possible in a very MVVM friendly way.

First step is to add the DescriptionAttribute to the values of the enumeration.

public enum MyValues
{
    [Description("First value")]
    First,

    [Description("Second value")]
    Second
}

To retrieve the description from the enum we use a simple extension method. This method returns the value of the DescriptionAttribute if it exists, otherwise the string representation of the enum value is returned.

public static string GetDescription(this Enum value)
{
    var fieldInfo = value.GetType().GetField(value.ToString());
    var attribute = fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false).FirstOrDefault() as DescriptionAttribute;

    return attribute != null ? attribute.Description : value.ToString();
}

With this extension method it is really easy to write a generic enum description converter to use where ever an enum value is presented to the user. But the more interesting case is where we want to present the enumeration in a ComboBox or a similar control. To accomplish this you can use a MarkupExtension. (Please note that this code is stripped from all type validation and such to be easier to read.)

public class EnumExtension : MarkupExtension
{
    private readonly Type _enumType;

    public EnumExtension(Type enumType)
    {
        _enumType = enumType;
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return (from object enumValue in Enum.GetValues(_enumType)
                select new EnumMember {Value = enumValue, Description = ((Enum)enumValue).GetDescription()}).ToArray();
    }

    public class EnumMember
    {
        public string Description { get; set; }
        public object Value { get; set; }
    }
}

The DescriptionAttribute together with these extensions gives us a really neat way of populating the values of an enum into a ComboBox.

<ComboBox SelectedValue="{Binding MyValue}"
          ItemsSource="{Binding Source={my:EnumExtension {x:Type MyValues}}}"
          DisplayMemberPath="Description" SelectedValuePath="Value" />

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