为什么我不能用一个DataTrigger设置TextBox.IsEnabled =真实的吗？ [英] Why can't I use a DataTrigger to set TextBox.IsEnabled = True?

问题描述

在我的申请，我有，我想根据我的datacontext枚举启用/禁用一个TextBox。枚举有三个值（任何人，我，有人），我想，当值有人设置为启用文本框。我能够通过设置在反（见下文）的值来破解的溶液。然而，有人可以请解释为什么第一个解决方案没有奏效？

这不工作...

 ＆LT;文本框的文本={结合ModifiedUser，UpdateSourceTrigger =的PropertyChanged}
         IsEnabled =FALSE＆GT;
    ＆LT; TextBox.Style＆GT;
        ＆LT;风格的TargetType ={X：TextBox类型}＆GT;
            ＆LT; Style.Triggers＆GT;
                ＆LT; D​​ataTrigger绑定={结合ModifiedBy}
                             值=有人＆GT;
                    ＆LT; setter属性=IsEnabled
                            值=真/＆GT;
                ＆LT; / DataTrigger＆GT;
            ＆LT; /Style.Triggers>
        ＆LT; /样式和GT;
    ＆LT; /TextBox.Style>
＆LT; /文本框＆GT;
 

奇怪的是，这个code 确实的工作。

 ＆LT;文本框的文本={结合ModifiedUser，UpdateSourceTrigger =的PropertyChanged}＆GT;
    ＆LT; TextBox.Style＆GT;
        ＆LT;风格的TargetType ={X：TextBox类型}＆GT;
            ＆LT; Style.Triggers＆GT;
                ＆LT; D​​ataTrigger绑定={结合ModifiedBy}
                             值=任何人＆GT;
                    ＆LT; setter属性=IsEnabled
                            值=FALSE/＆GT;
                ＆LT; / DataTrigger＆GT;
                ＆LT; D​​ataTrigger绑定={结合ModifiedBy}
                             VALUE =我＆GT;
                    ＆LT; setter属性=IsEnabled
                            值=FALSE/＆GT;
                ＆LT; / DataTrigger＆GT;
            ＆LT; /Style.Triggers>
        ＆LT; /样式和GT;
    ＆LT; /TextBox.Style>
＆LT; /文本框＆GT;
 

解决方案

您必须设置初始isEnabled在你的风格了。否则你的本地IsEnabled = FALSE将永远是赢家！

改变你的风格，它会正常工作。

 ＆LT;文本框的文本={结合ModifiedUser，UpdateSourceTrigger =的PropertyChanged}＆GT;
＆LT; TextBox.Style＆GT;
    ＆LT;风格的TargetType ={X：TextBox类型}＆GT;
        ＆LT; setter属性=IsEnabledVALUE =FALSE/＆GT;
        ＆LT; Style.Triggers＆GT;
            ＆LT; D​​ataTrigger绑定={结合ModifiedBy}
                         值=有人＆GT;
                ＆LT; setter属性=IsEnabled
                        值=真/＆GT;
            ＆LT; / DataTrigger＆GT;
        ＆LT; /Style.Triggers>
    ＆LT; /样式和GT;
＆LT; /TextBox.Style>
 

In my application, I have a TextBox that I want to enable/disable based on an enum in my datacontext. The enum has three values (Anyone, Me, Someone) and I want to enable the Textbox when the value "Someone" is set. I am able to hack a solution by setting the value in reverse (see below). However, can someone please explain why the first solution didn't work?

This does not work...

<TextBox Text="{Binding ModifiedUser, UpdateSourceTrigger=PropertyChanged}"
         IsEnabled="False">
    <TextBox.Style>
        <Style TargetType="{x:Type TextBox}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding ModifiedBy}"
                             Value="Someone">
                    <Setter Property="IsEnabled"
                            Value="True" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TextBox.Style>
</TextBox>

Strangely, this code does work.

<TextBox Text="{Binding ModifiedUser, UpdateSourceTrigger=PropertyChanged}">
    <TextBox.Style>
        <Style TargetType="{x:Type TextBox}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding ModifiedBy}"
                             Value="Anyone">
                    <Setter Property="IsEnabled"
                            Value="False" />
                </DataTrigger>
                <DataTrigger Binding="{Binding ModifiedBy}"
                             Value="Me">
                    <Setter Property="IsEnabled"
                            Value="False" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TextBox.Style>
</TextBox>

解决方案

you have to set the initial isEnabled in your style too. otherwise your "local" IsEnabled=false will always win!

change your style and it will work.

<TextBox Text="{Binding ModifiedUser, UpdateSourceTrigger=PropertyChanged}">
<TextBox.Style>
    <Style TargetType="{x:Type TextBox}">
        <Setter Property="IsEnabled" Value="False" />
        <Style.Triggers>
            <DataTrigger Binding="{Binding ModifiedBy}"
                         Value="Someone">
                <Setter Property="IsEnabled"
                        Value="True" />
            </DataTrigger>
        </Style.Triggers>
    </Style>
</TextBox.Style>

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