wpf 空字符串上的数据触发器
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/19236137/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Datatrigger on empty string
提问by Giffesnaffen
How can a DataTrigger change the visibility of stackpanel, based on a binded string? I have the following Xaml
DataTrigger 如何根据绑定字符串更改堆栈面板的可见性？我有以下 Xaml
<StackPanel HorizontalAlignment="Right"
Orientation="Horizontal"
Grid.Column="1"
Background="#FF7a7a7a">
<StackPanel.Style>
<Style TargetType="{x:Type StackPanel}">
<Style.Triggers>
<DataTrigger Binding="{Binding SearchText}" Value="">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
</Style.Triggers>
</Style>
</StackPanel.Style>
Content....
</StackPanel>
I Know that SearchTextgets updates and binds properly outside the StackPanel
我知道SearchText在外部获取更新并正确绑定StackPanel
Could somebody point me in the right direction?
有人能指出我正确的方向吗？
回答by Federico Berasategui
This:
这个：
<DataTrigger Binding="{Binding SearchText}" Value="">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
will work for empty string (""), however it will not work for null.
将适用于空字符串 ( "")，但不适用于null.
Add another DataTriggerfor the null case:
DataTrigger为空情况添加另一个：
<DataTrigger Binding="{Binding SearchText}" Value="{x:Null}">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
回答by Butsaty
Correct using String.Empty in XAML:
在 XAML 中正确使用 String.Empty：
xmlns:sys="clr-namespace:System;assembly=mscorlib"
...
<DataTrigger Binding="{Binding SearchText}" Value="{x:Static sys:String.Empty}">
回答by Tico
Weird as it might sound, the code below works for me:
听起来很奇怪，下面的代码对我有用：
<StackPanel Background="#FF7a7a7a">
<StackPanel.Style>
<Style TargetType="{x:Type StackPanel}">
<Style.Triggers>
<DataTrigger Binding="{Binding Text, ElementName=textBlock}" Value="">
<Setter Property="Visibility" Value="Hidden"/>
</DataTrigger>
</Style.Triggers>
</Style>
</StackPanel.Style>
<TextBox x:Name="textBlock" Text="" Width="100" Height="30"></TextBox>
</StackPanel>
Can you tell the value your Property is sending?
你能说出你的财产发送的价值吗？
回答by Rahul Misra
Try this
尝试这个
<StackPanel.Style>
<Style TargetType="StackPanel">
<Setter Property="Visibility" Value="Collapsed"/>
<Style.Triggers>
<DataTrigger Binding="{Binding YourBoundPropertyName}" Value="True">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</StackPanel.Style>
