WPF binding ComboBox to enum (with a twist)

Asked 2009-05-27T15:04:12.940

Well the problem is that I have this enum, BUT I don't want the combobox to show the values of the enum. This is the enum:

public enum Mode
    {
        [Description("Display active only")]
        Active,
        [Description("Display selected only")]
        Selected,
        [Description("Display active and selected")]
        ActiveAndSelected
    }

So in the ComboBox instead of displaying Active, Selected or ActiveAndSelected, I want to display the DescriptionProperty for each value of the enum. I do have an extension method called GetDescription() for the enum:

public static string GetDescription(this 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;
            }
        }

So is there a way I can bind the enum to the ComboBox AND show it's content with the GetDescription extension method?

Thanks!

Edit Report

2 Answers

I like the way you think. But GetCustomAttributes uses reflection. What is that going to do to your performance?

Check out this post: WPF - Displaying enums in ComboBox control http://www.infosysblogs.com/microsoft/2008/09/wpf_displaying_enums_in_combob.html

answered 2009-05-27T15:20:38.400

I suggest you use a markup extension I had already posted here, with just a little modification :

[MarkupExtensionReturnType(typeof(IEnumerable))]
public class EnumValuesExtension : MarkupExtension
{
    public EnumValuesExtension()
    {
    }

    public EnumValuesExtension(Type enumType)
    {
        this.EnumType = enumType;
    }

    [ConstructorArgument("enumType")]
    public Type EnumType { get; set; }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        if (this.EnumType == null)
            throw new ArgumentException("The enum type is not set");
        return Enum.GetValues(this.EnumType).Select(o => GetDescription(o));
    }
}

You can then use it like that :

<ComboBox ItemsSource="{local:EnumValues local:Mode}"/>

EDIT: the method I suggested will bind to a list of string, which is not desirable since we want the SelectedItem to be of type Mode. It would be better to remove the .Select(...) part, and use a binding with a custom converter in the ItemTemplate.

answered 2009-05-27T15:33:31.837

WPF binding ComboBox to enum (with a twist)

2 Answers

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