WPF – Enum Binding in a ComboBox – The Other Way

Hello Devz,

In a previous post I was talking about the fact that there is no “out-of-the-box” solution to bind an Enum to a ComboBox. And I described the WPF way of doing it with the ObjectDataProvider defined in the XAML.

Here is another way, more code oriented than XAML.

This is the XAML part:

<ComboBox HorizontalAlignment="Center" VerticalAlignment="Center" MinWidth="150" 
ItemsSource="{Binding Source={local:EnumBindingSource {x:Type local:StatusEnum}}}"/>

Here is our Enum:

public enum StatusEnum
{
    None = 0,
    Waiting = 1,
    Running = 2,
    Success = 3,
    Warning = 4,
    Error = 5
}

And here is our MarkupExtension:

using System;
using System.Windows.Markup;

namespace EnumBindingMarkupExtension
{
    public class EnumBindingSourceExtension : MarkupExtension
    {
        private Type _enumType;
        public Type EnumType
        {
            get { return this._enumType; }
            set
            {
                if (value != this._enumType)
                {
                    if (null != value)
                    {
                        Type enumType = Nullable.GetUnderlyingType(value) ?? value;

                        if (!enumType.IsEnum)
                            throw new ArgumentException("Type must be an Enum.");
                    }

                    this._enumType = value;
                }
            }
        }

        public EnumBindingSourceExtension() { }

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

        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            if (null == this._enumType)
                throw new InvalidOperationException("The EnumType must be specified.");

            Type actualEnumType = Nullable.GetUnderlyingType(this._enumType) ?? this._enumType;
            Array enumValues = Enum.GetValues(actualEnumType);

            if (actualEnumType == this._enumType)
                return enumValues;

            Array tempArray = Array.CreateInstance(actualEnumType, enumValues.Length + 1);
            enumValues.CopyTo(tempArray, 1);
            return tempArray;
        }
    }
}

If you want to go further, please have a look to the best way to bind your Enum to a ComboBox with the Description Attribute in your MVVM WPF application.

Happy binding!  😉

Related posts:

WPF – Enum Binding in a ComboBox – The Classic Way WPF – Enum Binding With Description in a ComboBox WPF – Nullable binding C# – Enum Color Converter with IValueConverter