DataTriggerBehavior不能使用枚举？ [英] DataTriggerBehavior Doesn't Work With Enum?

问题描述

我正在尝试使用行为SDK中的 DataTriggerBehavior 。但是它似乎不适用于枚举...或者我做错了。

I'm trying to use a DataTriggerBehavior from the Behaviors SDK. But it doesn't seem to work with enums... or else I'm doing something wrong.

你可以假设 DataContext 这些例子是这样的（ INotifyPropertyChanged 被实现，但我不会在这里显示）：

You can assume that the DataContext for these examples is something like this (INotifyPropertyChanged is implemented, but I'm not going to show it here):

public class MyDataClass
{
    public MyEnum ItemCommand { get; set; }
    public string ItemCommandString { get; set; }
}

public enum MyEnum
{
    EnumValue1
}

_Button.DataContext = new MyDataClass() { ItemCommand = MyEnum.EnumValue1, 
                                          ItemCommandString = "EnumValue1" };

这是代码不起作用（试图指定枚举值并检查ItemCommand枚举属性）：

Here is the code that doesn't work (trying to specify an enum value and check against the ItemCommand enum property):

<ToggleButton x:Name="_Button">
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding ItemCommand}" 
                                  Value="EnumValue1">
            <Core:ChangePropertyAction PropertyName="Command" 
                                       TargetObject="{Binding ElementName=_Button}"
                                       Value="{x:Null}">
            </Core:ChangePropertyAction>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</ToggleButton>

此代码（针对枚举资源进行检查）也不起作用：

and this code (checking against an enum resource) also does not work:

<UserControl.Resources>
    <local:MyEnum x:Key="_MyEnumValue">EnumValue1</local:MyEnum>
</UserControl.Resources>

<ToggleButton x:Name="_Button">
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding ItemCommand}" 
                                  Value="{StaticResource _MyEnumValue}">
            <Core:ChangePropertyAction PropertyName="Command" 
                                       TargetObject="{Binding ElementName=_Button}"
                                       Value="{x:Null}">
            </Core:ChangePropertyAction>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</ToggleButton>

而这段代码（检查字符串）是否正常工作：

whereas this code (checking against a string) does work:

<ToggleButton x:Name="_Button">
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding ItemCommandString}" 
                                  Value="EnumValue1">
            <Core:ChangePropertyAction PropertyName="Command" 
                                       TargetObject="{Binding ElementName=_Button}"
                                       Value="{x:Null}">
            </Core:ChangePropertyAction>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</ToggleButton>

在 DataTriggerBehavior 中指定枚举值的正确方法是什么？ code> 值属性，以便这将工作？

What is the correct way to specify the enum value in the DataTriggerBehavior Value property so that this will work?

推荐答案

你可以写一个转换器：

 public class MyEnumConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, string language)
        {
            MyEnum myEnumValue = (MyEnum)value;
            return myEnumValue.ToString();
        }

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

并在XAML中使用它：

And use it in XAML:

<ToggleButton x:Name="_Button">
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding ItemCommand, Converter={StaticResource MyEnumConverter}}" 
                                  Value="EnumValue1">
            <Core:ChangePropertyAction PropertyName="Command" 
                                       TargetObject="{Binding ElementName=_Button}"
                                       Value="{x:Null}">
            </Core:ChangePropertyAction>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</ToggleButton>

或直接绑定到您的示例中的字符串。不幸的是WinRT中的DataTriggerBehavior更糟糕的是Windows Phone 8中的DataTrigger

Or bind direct to the string as in your sample. Unfortunately DataTriggerBehavior in WinRT is worse that DataTrigger in Windows Phone 8

这篇关于DataTriggerBehavior不能使用枚举？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！