自定义文本框的 WPF 验证 ErrorTemplate
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WPF Validation ErrorTemplate for Custom TextBox
提问by Duke Cyrillus
Branching off of thisquestion -
这个问题的分支-
When attaching a validation error template to my custom textbox like this -
当像这样将验证错误模板附加到我的自定义文本框时 -
<local:CustomTextBox CustomText="{Binding ViewModelProperty}" Validation.ErrorTemplate="{StaticResource errorTemplate}"/>
<ControlTemplate x:Key="errorTemplate">
<DockPanel>
<Border BorderBrush="Red" BorderThickness="1">
<AdornedElementPlaceholder x:Name="controlWithError"/>
</Border>
<TextBlock Foreground="Red" FontSize="20" FontFamily="Segoe UI" Margin="3,0,0,0" MouseDown="Exclamation_MouseDown" Tag="{Binding AdornedElement.(Validation.Errors)[0].ErrorContent, ElementName=controlWithError}">!</TextBlock>
</DockPanel>
</ControlTemplate>
If there was a validation error in the ViewModelProperty, my application was throwing an exception -
如果 ViewModelProperty 中存在验证错误，我的应用程序将抛出异常 -
Key cannot be null.
Parameter name: key
I'm not sure why this is happening. Is there something that needs to be done in order to assign a new error template to a custom control?
我不确定为什么会这样。是否需要做一些事情才能将新的错误模板分配给自定义控件？
UPDATE:
更新：
I've figured out that the issue is with the Tag property in the error template. If I remove the Tag, it works just fine.
我发现问题出在错误模板中的 Tag 属性上。如果我删除标签，它工作得很好。
Thanks
谢谢
回答by Duke Cyrillus
Alright so the way I managed to fix the issue was by removing the AdornedElement keyword and changing the error template as follows:
好吧，我设法解决这个问题的方法是删除 AdornedElement 关键字并按如下方式更改错误模板：
<local:CustomTextBox CustomText="{Binding ViewModelProperty}">
<Validation.ErrorTemplate>
<ControlTemplate>
<DockPanel>
<Border BorderBrush="Red" BorderThickness="1">
<AdornedElementPlaceholder x:Name="controlWithError"/>
</Border>
<TextBlock Foreground="Red" FontSize="20" FontFamily="Segoe UI" Margin="3,0,0,0" MouseDown="Exclamation_MouseDown">!</TextBlock>
</DockPanel>
</ControlTemplate>
</Validation.ErrorTemplate>
<local:CustomTextBox.Style>
<Style TargetType="{x:Type local:CustomTextBox}">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors)[0].ErrorContent}"/>
<Setter Property="Tag" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors)[0].ErrorContent}"/>
</Trigger>
</Style.Triggers>
</Style>
</local:CustomTextBox.Style>
</local:CustomTextBox>
What I don't understand is why it behaves differently when using the AdornedElement keyword but works fine when binding the Tag/Tooltip using the RelativeSource. While the problem is solved, I would welcome any ideas as to why this happened.
我不明白的是为什么它在使用 AdornedElement 关键字时表现不同，但在使用 RelativeSource 绑定标签/工具提示时却能正常工作。虽然问题解决了，但我欢迎任何关于为什么会发生这种情况的想法。
Thanks
谢谢
