How to bind dropdownlist from enum - drop-down-menu

Question

I have an enum
public enum LookupTypes
{
[StringValue("UNIV")]
University,
[StringValue("COUR")]
Course}
How can i bind this in dropdownlist with UNIV as value and University as Text
c#/WPF

Answer 1

You'll need a few converters:
To display enum list ("University", "Course"), you'll need EnumValuesConverter, it's wrapping "enumType.getValues()"
Then you can use the provided extension method StringValue() to get the attribute's value.
Or use a converter EnumToStringValueConverter which does the same, to display the value on the UI (see Labels)
If by "with UNIV as value" you meant, combo.SelectedValue to be string UNIV tough luck, because SelectedValuePath doesn't handle functions, only properties.
Try this beast:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:app="clr-namespace:WpfApplication1"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<app:EnumValuesConverter x:Key="enumValuesConverter" />
<app:EnumToStringValueConverter x:Key="enumToStringValueConverter" />
</Window.Resources>
<StackPanel x:Name="context">
<ComboBox x:Name="combo"
ItemsSource="{Binding Source={x:Type app:LookupTypes}, Mode=OneTime, Converter={StaticResource enumValuesConverter}}"
SelectedItem="{Binding EnumProp, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
<ComboBox.ItemTemplate>
<DataTemplate>
<Label Content="{Binding}" ToolTip="{Binding Converter={StaticResource enumToStringValueConverter}}" />
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
<Label Content="{Binding EnumProp}" ContentStringFormat="Selected Enum: {0}" />
<Label Content="{Binding EnumProp, Converter={StaticResource enumToStringValueConverter}}" ContentStringFormat="Selected StringValue: {0}" />
<Button Click="Button_Click" Content="Alert enum" />
</StackPanel>
</Window>
Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace WpfApplication1 {
public partial class MainWindow : Window {
public MainWindow() {
InitializeComponent();
context.DataContext = new MyViewModel {
EnumProp = LookupTypes.Course
};
}
private void Button_Click(object sender, RoutedEventArgs e) {
LookupTypes type = (LookupTypes)combo.SelectedItem;
MessageBox.Show(string.Format("Are you sure you want to use {0} ({1}) as lookup type?", type, type.StringValue()));
}
}
[global::System.AttributeUsage(AttributeTargets.Field, AllowMultiple = false)]
public sealed class StringValueAttribute : Attribute {
public StringValueAttribute(string stringValue) {
StringValue = stringValue;
}
public string StringValue { get; private set; }
}
public static class StringValueExtensions {
public static string StringValue(this Enum This) {
System.Reflection.FieldInfo fieldInfo = This.GetType().GetField(This.ToString());
StringValueAttribute[] attribs = fieldInfo.GetCustomAttributes(typeof(StringValueAttribute), false) as StringValueAttribute[];
return attribs.Length == 0 ? null : attribs[0].StringValue;
}
}
public enum LookupTypes {
[StringValue("UNIV")]
University,
[StringValue("COUR")]
Course
}
class MyViewModel {
public LookupTypes EnumProp { get; set; }
}
[ValueConversion(typeof(Enum), typeof(string[]))]
public class EnumValuesConverter : IValueConverter {
#region IValueConverter Members
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) {
if (value == null) return Binding.DoNothing;
return Enum.GetValues((Type)value);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) {
throw new NotImplementedException();
}
#endregion
}
[ValueConversion(typeof(Enum), typeof(string))]
public class EnumToStringValueConverter : DependencyObject, IValueConverter {
#region IValueConverter Members
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) {
if (value == null) return Binding.DoNothing;
return ((Enum)value).StringValue();
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) {
throw new NotImplementedException();
}
#endregion
}
}