Converter to show description of an enum, and convert back to enum value on selecting an item from combo box in wpf

Question

I am using an enum to enlist values in my combobox. I want to write a converter that would show the "description" of the selected enum value. And, when selected, it would return the enum value.

Most of the converters online have not implemented the ConvertBack() method (which is why I am posting here).

For some really nice solutions, see http://stackoverflow.com/questions/58743/databinding-an-enum-property-to-a-combobox-in-wpf. — Contango, Jan 28 '16 at 13:09

Suresh · Accepted Answer · 2019-06-29T04:25:01.653

Here is ConvertBack method:

public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
    return value;
}

Full Converter Code:

public class EnumConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (value == null) return DependencyProperty.UnsetValue;

        return GetDescription((Enum)value);
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return value;
    }

    public static string GetDescription(Enum en)
    {
        Type type = en.GetType();
        MemberInfo[] memInfo = type.GetMember(en.ToString());
        if (memInfo != null && memInfo.Length > 0)
        {
            object[] attrs = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
            if (attrs != null && attrs.Length > 0)
            {
                return ((DescriptionAttribute)attrs[0]).Description;
            }
        }
        return en.ToString();
    }
}

EDIT

Here is my ComboBox XAML:

<ComboBox ItemsSource="{Binding SampleValues}" 
          SelectedItem="{Binding SelectedValue, Converter={StaticResource enumConverter}}">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Path=., Converter={StaticResource enumConverter}}" />
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

I am manipulating the data template of the combo box to show me the description values of the enum. But the selected item still shows the original enum value. Is there a way i can manipulate that as well? — aromore, Nov 29 '13 at 19:00
ohh..i just needed to pass it through the converter... thanks! — aromore, Nov 29 '13 at 19:26
@aromore Updated answer, please check the updated `ConvertBack` memthod. — Suresh, Nov 30 '13 at 02:02

score 10 · Answer 2 · answered May 02 '16 at 16:25

I know this is an old question, but for some reason, this is rather complicated, even though it seems like it'd be a pretty common task (I'm currently doing this on a UWP app). Using a combination of the accepted answer, some other items I found, and a bit of my own work, here's the simplest way I've found to accomplish this menial task. In short:

Define your enum along w/ setting the description in the Display attribute
Create a converter that converts from an enum value to the description
In your viewmodel, expose a collection of enum values from which to choose, the selected enum value, then initialize those
Define a couple of handy enum extension methods
Finally, some simple binding to the ComboBox, just overriding its ItemTemplate to use the converter.

Enum

public enum EnumOptions
{
    [Display(Description = "Option 1")]
    OptionOne= 1,
    [Display(Description = "Option 2")]
    OptionTwo,
    [Display(Description = "Option 3")]
    OptionThree
}

Converter

public class EnumToDisplayConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        var enumValue = value as Enum;

        return enumValue == null ? DependencyProperty.UnsetValue : enumValue.GetDescriptionFromEnumValue();
    }

    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        return value;
    }
}

Viewmodel (partial)

public IReadOnlyList<EnumOptions> Options { get; }

private EnumOptions _selectedOption;

public EnumOptions SelectedOption
{
    get { return _selectedOption; }
    set
    {
        _selectedOption = value;
        OnPropertyChanged(() => SelectedOption);
    }
}

// Initialization in constructor
Options = EnumExtensions.GetValues<EnumOptions>().ToArray();
// If you want to set a default.
SelectedOption = Options[0];

Extensions

public static class EnumExtensions
{
    public static string GetDescriptionFromEnumValue(this Enum value)
    {
        var attribute = value.GetType()
            .GetField(value.ToString())
            .GetCustomAttributes(typeof(DisplayAttribute), false)
            .SingleOrDefault() as DisplayAttribute;
        return attribute == null ? value.ToString() : attribute.Description;
    }

    /// <summary>
    /// Enumerates all enum values
    /// </summary>
    /// <typeparam name="T">Enum type</typeparam>
    /// <returns>IEnumerable containing all enum values</returns>
    /// <see cref="http://stackoverflow.com/questions/972307/can-you-loop-through-all-enum-values"/>
    public static IEnumerable<T> GetValues<T>()
    {
        return Enum.GetValues(typeof (T)).Cast<T>();
    }
}

XAML (partial)

<TextBlock Grid.Row="1">Choose an option</TextBlock>
<ComboBox Grid.Row="2"
          ItemsSource="{Binding Options}"
          SelectedItem="{Binding SelectedOption, Mode=TwoWay}">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Converter={StaticResource EnumToDisplayConverter}}"></TextBlock>
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

I tried your approach, but I get the exception: "Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead." related to the SelectedItem while I run the application. — Francesco, Jan 19 '17 at 09:26

score 2 · Answer 3 · answered Nov 29 '13 at 17:45

[ValueConversion(typeof(MyEnum), typeof(String))]
public class MyEnumConverter : IValueConverter
{
    public object Convert(object value,
        Type targetType,
        object parameter,
        CultureInfo culture)
    {
        var enumVal = (MyEnum)value;

        // in this example, this is an extension method
        return enumValue.Description();
    }

    public object ConvertBack(object value,
        Type targetType,
        object parameter,
        CultureInfo culture)
    {
        var enumDesc = value as string;
        MyEnum val;
        if (Enum.TryParse(typeof(MyEnum), strValue, out val))
        {
            return val;
        }
        return DependencyProperty.UnsetValue;
    }
}

The extension method in the example might look like this:

public static string Description(this MyEnum enumVal)
{
    // you could use a switch statement here;
    // or maybe a Dictionary
}

VijayKP · Answer 4 · 2013-11-29T19:47:33.277

Supplement to the above examples to show decorating the enum with attributes.

sealed class DescriptionAttribute : Attribute
{
    readonly string description;

    public DescriptionAttribute(string description)
    {
        this.description = description;
    }

    public string Description
    {
        get { return description; }
    }
}

enum Vehicle
{
    [Description("Benz")]
    Car,
    [Description("Volvo")]
    Bus,
    [Description("Honda")]
    Bike
}

BTW, I wonder why you needed to convert back the description to enum. If you provide the enums itself as ItemSource, you can use the description technique to show the display value in the ComboBox, however, once an item is selected you can directly have an enum as selected item.

score 0 · Answer 5 · answered Feb 12 '16 at 19:41

Here is my working well example:

Enum definition:

public enum MyEnum
{
    [Description("Exchange 2007")]
    E2007,
    [Description("Exchange 2010")]
    E2010,
    [Description("Exchange 2013")]
    E2013,
};

Helper class:

public static class cHelperClass
{
    #region GetValuesAndDescriptions
    public static object[] GetValuesAndDescriptions(Type enumType)
    {
        var kvPairList = new List<KeyValuePair<string, string>>();

        var listValue = Enum.GetValues(enumType);
        for (var i = 0; i < listValue.Length; i++)
        {
            var value = listValue.GetValue(i);
            var enumValue = (Enum)listValue.GetValue(i);
            kvPairList.Add(new KeyValuePair<string, string>(value.ToString(), GetDescription(enumValue)));
        }

        var valuesAndDescriptions = from kv in kvPairList select new
        {
            Value = kv.Key,
            Description = kv.Value
        };

        return valuesAndDescriptions.ToArray();
    }

    public static string GetDescription(this Enum value)
    {
        var fieldInfo = value.GetType().GetField(value.ToString());
        var attributes = (DescriptionAttribute[])fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);
        return (attributes.Length > 0) ? attributes[0].Description : value.ToString();
    }
    public static string GetStringValue(this Enum enumItem)
    {
        return enumItem
            .GetType()
            .GetField(enumItem.ToString())
            .GetCustomAttributes<StringValueAttribute>()
            .Select(a => a.Value)
            .FirstOrDefault() ?? enumItem.ToString();
    }

    public static string GetName(Type enumType, object value)
    {
        return Enum.GetName(enumType, value);
    }
    #endregion
}

XAML:

<UserControl.Resources>
    <!-- ObjectDataProvider für WindowStyles -->
    <ObjectDataProvider x:Key="myEnumResource" MethodName="GetValuesAndDescriptions" ObjectType="classes:cHelperClass">
        <ObjectDataProvider.MethodParameters>
            <x:Type TypeName="classes:MyEnum" />
        </ObjectDataProvider.MethodParameters>
    </ObjectDataProvider>
</UserControl.Resources>


<ComboBox ItemsSource="{Binding Source={StaticResource myEnumResource}}" DisplayMemberPath="Description" SelectedValuePath="Value" SelectedValue="{Binding MyEnum, Mode=TwoWay}" />

Converter to show description of an enum, and convert back to enum value on selecting an item from combo box in wpf

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