将转换后的Enum绑定到ComboBox

Question

我试图将以下枚举绑定到ComboBox

Public Enum PossibleActions
  ActionRead
  ActionWrite
  ActionVerify
End Enum

我不能改变Enum本身,但我不想显示这些字符串.我的目的只是剪切前缀'Action'并在ComboBox中显示'Read','Write'和'Verify'.因此我写了一个ValueConverter

Public Class PossibleActionsConverter
  Implements IValueConverter

      Public Function Convert(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.Convert
        Dim actions() As PossibleActions
        Dim strings() As String

        actions = CType(value, PossibleActions())
        ReDim strings(actions.GetUpperBound(0))
        For i = 0 To actions.GetUpperBound(0)
          strings(i) = actions(i).ToString.Substring(6)
        Next
        Return strings
      End Function

      Public Function ConvertBack(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.ConvertBack
        Dim s As String

        s = CStr(value)

        Return [Enum].Parse(GetType(PossibleActions), "Action" & s)
      End Function
    End Class

我的XAML看起来像

xmlns:sys="clr-namespace:System;assembly=mscorlib"
xmlns:local="clr-namespace:StepEditor"

[...]

<Window.Resources>
    <ObjectDataProvider x:Key="possibleActionsEnum" MethodName="GetValues"
                        ObjectType="{x:Type sys:Enum}">
        <ObjectDataProvider.MethodParameters>
            <x:TypeExtension Type="local:PossibleActions"></x:TypeExtension>
        </ObjectDataProvider.MethodParameters>
    </ObjectDataProvider>
    <local:PossibleActionsConverter x:Key="possibleActionsConverter"></local:PossibleActionsConverter>
</Window.Resources>

[...]
要么:

<ComboBox ItemsSource="{Binding Source={StaticResource possibleActionsEnum}, Converter={StaticResource possibleActionsConverter}}"
          SelectedItem="{Binding SelectedAction}"></ComboBox>

要么:

<ComboBox ItemsSource="{Binding Source={StaticResource possibleActionsEnum}, Converter={StaticResource possibleActionsConverter}}"
          SelectedItem="{Binding SelectedAction, Converter={StaticResource possibleActionsConverter}}"></ComboBox>

我的问题是所选项目的绑定.它失败了,但我无法弄清楚原因.

Answer 1

SelectedItem 的绑定是错误的，因为您将 Enum 转换为字符串，但 SelectedItems 是单个字符串。如果您想坚持这种架构，请编写一个转换器将单个字符串转换回您的枚举。现有转换器的 Convert 和 ConvertBack 方法接近解决方案。它们可以看起来像：

  Public Function Convert(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.Convert
    Dim action As PossibleActions

    action = CType(value, PossibleActions)
    Return action.ToString.Substring(6)
  End Function

  Public Function ConvertBack(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.ConvertBack
    Dim s As String

    s = CStr(value)
    Return [Enum].Parse(GetType(PossibleActions), "Action" & s)
  End Function