如何在WPF中的Validation.ErrorTemplate中进行DataTrigger绑定

Question

我有一个被ControlTemplate包围的CustomControl 。 该CustomControl包含另一个CustomControl与Label ， TextBox和Validation.ErrorTemplate为TextBox 。

我想做的是，当我将CustomControl悬停或将TextBox放在焦点上时，将弹出Validation.ErrorTemplate 。

现在并且仅当我将Border悬停在TextBox周围时，它才弹出Validation.ErrorTemplate 。 老实说，我不确定它是StackPanel的Border还是AdornedElementPlaceholder的Border 。 我真的不知道如何将绑定DataTrigger里面Validation.ErrorTemplate到外Border IsMouseOver财产或IsFocused物业TextBox 。

在我到目前为止的代码下面：

<ControlTemplate TargetType="{x:Type my:CustomControl}" x:Key="CustomTemplate">
<Border BorderBrush="Green" BorderThickness="1" x:Name="outerBorder">
    <my:LabelControl Label="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=ViewModel.Label}">
        <TextBox HorizontalAlignment="Stretch" Padding="3 0 3 0" Foreground="{DynamicResource Control.Foreground}">
            <TextBox.Resources>
                <Style TargetType="{x:Type Border}">
                    <Setter Property="CornerRadius" Value="3"/>
                </Style>
            </TextBox.Resources>
            <TextBox.Text>
                <Binding Path="ViewModel.Value" UpdateSourceTrigger="PropertyChanged" RelativeSource="{RelativeSource TemplatedParent}" ValidatesOnDataErrors="True"/>
            </TextBox.Text>
            <TextBox.Style>
                <Triggers>
                    ...
                </Triggers>
            </TextBox.Style>
            <Validation.ErrorTemplate>
                <ControlTemplate>
                    <StackPanel x:Name="BorderBorder">
                        <Border BorderThickness="1" BorderBrush="Red" CornerRadius="3" HorizontalAlignment="Left" >
                            <AdornedElementPlaceholder x:Name="textBox"/>
                        </Border>
                        <Border Background="LightGoldenrodYellow"  CornerRadius="3">
                            <TextBlock Text="{Binding [0].ErrorContent}"/>
                            <Border.Style>
                                <Style>
                                    <Setter Property="Border.Visibility" Value="Collapsed"></Setter>
                                    <Style.Triggers>
                                        <DataTrigger Binding="{Binding ElementName=BorderBorder, Path=IsMouseOver}" Value="true">
                                            <Setter  Property="Border.Visibility" Value="Visible"></Setter>
                                        </DataTrigger>
                                    </Style.Triggers>
                                </Style>
                            </Border.Style>
                        </Border>
                    </StackPanel>
                </ControlTemplate>
            </Validation.ErrorTemplate>
        </TextBox>
    </my:LabelControl>
</Border>
</ControlTemplate>

因此，如果可能的话， Validation.ErrorTemplate内部的DataTrigger应该绑定到ElementName=outerBorder 。

我猜问题是我在ControlTemplate内有一个ControlTemplate所以内部ControlTemplate （ Validation.ErrorTemplate ）中的DataTrigger Binding不了解外部Properties 。

Answer 1

您可以将TextBox的Tag属性绑定到控件本身的IsMouseOver属性，然后将DataTrigger绑定到装饰元素的Tag属性：

<ControlTemplate TargetType="{x:Type my:CustomControl}" x:Key="CustomTemplate">
    <Border BorderBrush="Green" BorderThickness="1" x:Name="outerBorder">
        <my:LabelControl Label="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=ViewModel.Label}">
            <TextBox HorizontalAlignment="Stretch" Padding="3 0 3 0" Foreground="{DynamicResource Control.Foreground}"
                     Tag="{Binding IsMouseOver, RelativeSource={RelativeSource AncestorType=my:CustomControl}}">
                <TextBox.Resources>
                    <Style TargetType="{x:Type Border}">
                        <Setter Property="CornerRadius" Value="3"/>
                    </Style>
                </TextBox.Resources>
                <TextBox.Text>
                    <Binding Path="ViewModel.Value" UpdateSourceTrigger="PropertyChanged" RelativeSource="{RelativeSource TemplatedParent}" ValidatesOnDataErrors="True"/>
                </TextBox.Text>
                <Validation.ErrorTemplate>
                    <ControlTemplate>
                        <StackPanel x:Name="BorderBorder">
                            <Border BorderThickness="1" BorderBrush="Red" CornerRadius="3" HorizontalAlignment="Left" >
                                <AdornedElementPlaceholder x:Name="textBox"/>
                            </Border>
                            <Border Background="LightGoldenrodYellow"  CornerRadius="3">
                                <TextBlock Text="{Binding [0].ErrorContent}"/>
                                <Border.Style>
                                    <Style>
                                        <Setter Property="Border.Visibility" Value="Collapsed"></Setter>
                                        <Style.Triggers>
                                            <DataTrigger Binding="{Binding AdornedElement.(TextBox.Tag), ElementName=textBox}" Value="True">
                                                <Setter  Property="Border.Visibility" Value="Visible"></Setter>
                                            </DataTrigger>
                                        </Style.Triggers>
                                    </Style>
                                </Border.Style>
                            </Border>
                        </StackPanel>
                    </ControlTemplate>
                </Validation.ErrorTemplate>
            </TextBox>
        </my:LabelControl>
    </Border>
</ControlTemplate>