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

user_271106 0
Viewed 48461

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...?

enums data-binding listbox wpf c#
5 Answers

Another solution would be a custom MarkupExtension that generates the items from enum type. This makes the xaml more compact and readable. 

using System.ComponentModel;

namespace EnumDemo
{
    public enum Numbers
    {
        [Description("1")]
        One,

        [Description("2")]
        Two,

        Three,
    }
}

Example of usage:

<Window x:Class="EnumDemo.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:EnumDemo">

    <ListBox ItemsSource="{local:EnumToCollection EnumType={x:Type local:Numbers}}"/>

</Window>

MarkupExtension implementation

using System;
using System.ComponentModel;
using System.Linq;
using System.Windows.Markup;

namespace EnumDemo
{
    public class EnumToCollectionExtension : MarkupExtension
    {
        public Type EnumType { get; set; }

        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            if (EnumType == null) throw new ArgumentNullException(nameof(EnumType));

            return Enum.GetValues(EnumType).Cast<Enum>().Select(EnumToDescriptionOrString);
        }

        private string EnumToDescriptionOrString(Enum value)
        {
            return value.GetType().GetField(value.ToString())
                       .GetCustomAttributes(typeof(DescriptionAttribute), false)
                       .Cast<DescriptionAttribute>()
                       .FirstOrDefault()?.Description ?? value.ToString();
        }
    }
}
user_56127800

You can define a ressource file in your project (*.resx file). In this file you must define "key-value-pairs", something like this:

"YellowCars" : "Yellow Cars",
"RedCars" : "Red Cars",

and so on...

The keys are equals to your enum-entries, something like this:

public enum CarColors
{
    YellowCars,
    RedCars
}

and so on...

When you use WPF you can implement in your XAML-Code, something like this:

<ComboBox ItemsSource="{Binding Source={StaticResource CarColors}}" SelectedValue="{Binding CarColor, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Converter={StaticResource CarColorConverter}}" />
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

Then you must write your Converter, something like this:

using System;
using System.Globalization;
using System.Resources;
using System.Windows.Data;

public class CarColorConverter : IValueConverter
{
    private static ResourceManager CarColors = new ResourceManager(typeof(Properties.CarColors));

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var key = ((Enum)value).ToString();
        var result = CarColors.GetString(key);
        if (result == null) {
            result = key;
        }

        return result;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

My answer comes 7 years to late ;-) But maybe it can be used by someone else!

user_20639210

Yeah, possible.

ListBox can help us do that, without converters.

The steps of this method are below:
create a ListBox and set the ItemsSource for the listbox as the enum and binding the SelectedItem of the ListBox to the selected property.

Then each ListBoxItem will be created.

  • Step 1: define your Enum.
public enum EnumValueNames
{ 
   EnumValueName1, 
   EnumValueName2, 
   EnumValueName3
}

Then add below property to your DataContext (or ViewModel of MVVM), which records the selected item which is checked.

public EnumValueNames SelectedEnumValueName { get; set; }
  • Step 2: add the enum to static resources for your Window, UserControl or Grid etc.
    <Window.Resources>
        <ObjectDataProvider MethodName="GetValues"
                            ObjectType="{x:Type system:Enum}"
                            x:Key="EnumValueNames">
            <ObjectDataProvider.MethodParameters>
                <x:Type TypeName="local:EnumValueNames" />
            </ObjectDataProvider.MethodParameters>
        </ObjectDataProvider>
    </Window.Resources>
  • Step 3: Use the List Box to populate each item
<ListBox ItemsSource="{Binding Source={StaticResource EnumValueNames}}"
              SelectedItem="{Binding SelectedEnumValueName, Mode=TwoWay}" />

References: https://www.codeproject.com/Articles/130137/Binding-TextBlock-ListBox-RadioButtons-to-Enums

user_60753310
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