数据绑定一个枚举属性在WPF组合框 [英] Databinding an enum property to a ComboBox in WPF

问题描述

作为一个例子采取以下code：

As an example take the following code:

public enum ExampleEnum { FooBar, BarFoo }

public class ExampleClass : INotifyPropertyChanged
{
    private ExampleEnum example;

    public ExampleEnum ExampleProperty 
    { get { return example; } { /* set and notify */; } }
}

我希望有一个数据绑定属性ExampleProperty到一个ComboBox，这样它就会显示选项foobar如果和BarFoo，并在工作模式下双向。最理想我希望我的组合框的定义看起来是这样的：

I want a to databind the property ExampleProperty to a ComboBox, so that it shows the options "FooBar" and "BarFoo" and works in mode TwoWay. Optimally I want my ComboBox definition to look something like this:

<ComboBox ItemsSource="What goes here?" SelectedItem="{Binding Path=ExampleProperty}" />

目前，我有处理程序ComboBox.SelectionChanged和ExampleClass.PropertyChanged装在我的窗口，在这里我做事件手动绑定。

Currently I have handlers for the ComboBox.SelectionChanged and ExampleClass.PropertyChanged events installed in my Window where I do the binding manually.

有没有更好的或某种规范的方法？你通常会用转换器和你将如何填充正确的价值观的组合框？我甚至不希望开始与国际化现在。

Is there a better or some kind of canonical way? Would you usually use Converters and how would you populate the ComboBox with the right values? I don't even want to get started with i18n right now.

修改

所以，一个问题是回答：我如何填充组合框与正确的价值观

So one question was answered: How do I populate the ComboBox with the right values.

通过从静态Enum.GetValues​​方法的ObjectDataProvider的检索枚举值作为字符串列表：

Retrieve Enum values as a list of strings via an ObjectDataProvider from the static Enum.GetValues method:

<Window.Resources>
    <ObjectDataProvider MethodName="GetValues"
        ObjectType="{x:Type sys:Enum}"
        x:Key="ExampleEnumValues">
        <ObjectDataProvider.MethodParameters>
            <x:Type TypeName="ExampleEnum" />
        </ObjectDataProvider.MethodParameters>
    </ObjectDataProvider>
</Window.Resources>

这我可以作为一个的ItemsSource为我的组合框使用

<ComboBox ItemsSource="{Binding Source={StaticResource ExampleEnumValues}}"/>

推荐答案

您可以创建自定义标记扩展。

You can create a custom markup extension.

使用示例：

enum Status
{
    [Description("Available.")]
    Available,
    [Description("Not here right now.")]
    Away,
    [Description("I don't have time right now.")]
    Busy
}

<ComboBox 
    ItemsSource="{Binding Source={my:Enumeration {x:Type my:Status}}}" 
    DisplayMemberPath="Description" 
    SelectedValue="{Binding CurrentStatus}"  
    SelectedValuePath="Value"  /> 

和实施

public class EnumerationExtension : MarkupExtension
  {
    private Type _enumType;


    public EnumerationExtension(Type enumType)
    {
      if (enumType == null)
        throw new ArgumentNullException("enumType");

      EnumType = enumType;
    }

    public Type EnumType
    {
      get { return _enumType; }
      private set
      {
        if (_enumType == value)
          return;

        var enumType = Nullable.GetUnderlyingType(value) ?? value;

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

        _enumType = value;
      }
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
      var enumValues = Enum.GetValues(EnumType);

      return (
        from object enumValue in enumValues
        select new EnumerationMember{
          Value = enumValue,
          Description = GetDescription(enumValue)
        }).ToArray();
    }

    private string GetDescription(object enumValue)
    {
      var descriptionAttribute = EnumType
        .GetField(enumValue.ToString())
        .GetCustomAttributes(typeof (DescriptionAttribute), false)
        .FirstOrDefault() as DescriptionAttribute;


      return descriptionAttribute != null
        ? descriptionAttribute.Description
        : enumValue.ToString();
    }

    public class EnumerationMember
    {
      public string Description { get; set; }
      public object Value { get; set; }
    }
  }

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