WPF 数据验证中的绑定失败
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【中文标题】WPF 数据验证中的绑定失败【英文标题】：Failed Binding in WPF Data Validation 【发布时间】：2012-12-22 13:32:54 【问题描述】：我正在尝试将我的控件样式中的属性绑定到控件中定义的属性。该控件继承自 TextBox，称为 ChangeTextBoxWithRangeUnits。我正在尝试从我创建的 ValidationRule 类绑定到它们。这是我尝试验证文本的设置器
<Setter Property="Text">
<Setter.Value>
<Binding RelativeSource="RelativeSource Self"
Path="Text"
NotifyOnValidationError="True">
<Binding.ValidationRules>
<basic:DoubleValidationRule>
<basic:DoubleValidationRule.MinMaxDependencyObject>
<basic:MinMaxDependencyObject Minimum="Binding RelativeSource=RelativeSource Mode=FindAncestor, AncestorType=x:Type local:ChangeTextBoxWithRangeUnits, Path=MinimumValue"
Maximum="Binding RelativeSource=RelativeSource Mode=FindAncestor, AncestorType=x:Type local:ChangeTextBoxWithRangeUnits, Path=MaximumValue" />
</basic:DoubleValidationRule.MinMaxDependencyObject>
</basic:DoubleValidationRule>
</Binding.ValidationRules>
</Binding>
</Setter.Value>
</Setter>
我不明白为什么它说找不到源绑定。这是错误：
System.Windows.Data 错误：4：找不到与引用“RelativeSource FindAncestor，AncestorType='Frasca.Simplicity.Controls.UnitControls.ChangeTextBoxWithRangeUnits'，AncestorLevel='1''的绑定源。绑定表达式：路径=最小值；数据项=空；目标元素是“MinMaxDependencyObject”（HashCode=16320155）；目标属性是“最小”（类型“双”）
编辑完整的 XAML
<Style x:Key="ChangeTextBoxWithRangeUnits"
TargetType="x:Type local:ChangeTextBoxWithRangeUnits"
BasedOn="StaticResource x:Type TextBox">
<Setter Property="Validation.ErrorTemplate"
Value="x:Null" />
<Setter Property="Height"
Value="64" />
<Setter Property="FontSize"
Value="22" />
<Setter Property="Margin"
Value="5" />
<Setter Property="Background"
Value="LightGray" />
<Setter Property="BorderThickness"
Value="0" />
<Setter Property="KeyboardNavigation.TabNavigation"
Value="None" />
<Setter Property="AllowDrop"
Value="true" />
<Setter Property="ScrollViewer.PanningMode"
Value="VerticalFirst" />
<Setter Property="Stylus.IsFlicksEnabled"
Value="False" />
<Setter Property="Text">
<Setter.Value>
<Binding RelativeSource="RelativeSource Self"
Path="Text"
NotifyOnValidationError="True">
<Binding.ValidationRules>
<basic:DoubleValidationRule>
<basic:DoubleValidationRule.MinMaxDependencyObject>
<basic:MinMaxDependencyObject Minimum="Binding RelativeSource=RelativeSource Mode=FindAncestor, AncestorType=x:Type local:ChangeTextBoxWithRangeUnits, Path=MinimumValue"
Maximum="Binding RelativeSource=RelativeSource Mode=FindAncestor, AncestorType=x:Type local:ChangeTextBoxWithRangeUnits, Path=MaximumValue" />
</basic:DoubleValidationRule.MinMaxDependencyObject>
</basic:DoubleValidationRule>
</Binding.ValidationRules>
</Binding>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="x:Type local:ChangeTextBoxWithUnits">
<Grid>
<Border Name="bg"
Background="TemplateBinding Background"
BorderBrush="TemplateBinding BorderBrush"
BorderThickness="TemplateBinding BorderThickness"
Width="TemplateBinding Width"
CornerRadius="15"
SnapsToDevicePixels="true">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="3*" />
<RowDefinition Height="Auto" />
<RowDefinition Height="2*" />
</Grid.RowDefinitions>
<StackPanel Orientation="Horizontal"
Grid.Row="0"
Name="mValueStackPanel"
VerticalAlignment="Bottom"
HorizontalAlignment="Center">
<ScrollViewer x:Name="PART_ContentHost"
SnapsToDevicePixels="TemplateBinding SnapsToDevicePixels" />
<TextBox Name="PART_UnitTextBlock"
Style="DynamicResource InlineTextBox"
Text="Binding RelativeSource=RelativeSource FindAncestor, AncestorType=x:Type local:ChangeTextBoxWithUnits, Path=Units"
FontSize="14"
Margin="3,0,0,0"
Foreground="TemplateBinding Foreground" />
</StackPanel>
<StackPanel Orientation="Horizontal"
Grid.Row="2"
HorizontalAlignment="Center"
VerticalAlignment="Top">
<TextBlock Text="Binding RelativeSource=RelativeSource FindAncestor, AncestorType=x:Type local:ChangeTextBoxWithUnits, Path=Label"
FontSize="14"
Foreground="TemplateBinding Foreground" />
</StackPanel>
<TextBlock Text="Binding RelativeSource=RelativeSource FindAncestor, AncestorType=x:Type local:ChangeTextBoxWithUnits, Path=DisabledText"
Foreground="TemplateBinding Foreground"
Grid.Row="0"
FontSize="14"
HorizontalAlignment="Center"
VerticalAlignment="Bottom"
Visibility="Collapsed"
x:Name="mDisabledTextBlock" />
<!-- Horizontal line -->
<Rectangle Height="1"
Margin="10,0"
Grid.Row="1"
Opacity="0.15"
SnapsToDevicePixels="True"
Fill="TemplateBinding Foreground" />
<!-- Object which flashes when the textbox is selected -->
<Border Grid.RowSpan="3"
Background="White"
Name="FlashObject"
CornerRadius="15"
Opacity="0">
<Border.Effect>
<BlurEffect Radius="20" />
</Border.Effect>
</Border>
<!-- Object which flashes when the textbox has a validation error-->
<Border Grid.RowSpan="3"
Grid.ColumnSpan="2"
Background="Red"
Name="ErrorFlashObject"
CornerRadius="15"
Opacity="0">
<Border.Effect>
<BlurEffect Radius="20" />
</Border.Effect>
</Border>
</Grid>
</Border>
<!-- Object which glows when the user makes a change to the text value. -->
<Border Width="Binding ElementName=bg, Path=ActualWidth"
Height="Binding ElementName=bg, Path=ActualHeight"
CornerRadius="15"
Background="#FFF066"
Name="ChangeGlowObject"
Panel.ZIndex="-1"
Visibility="Collapsed">
<Border.Effect>
<BlurEffect Radius="20" />
</Border.Effect>
</Border>
</Grid>
<ControlTemplate.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="HasChangedValue"
Value="True" />
<Condition Property="IsEnabled"
Value="True" />
</MultiTrigger.Conditions>
<Setter Property="Visibility"
TargetName="ChangeGlowObject"
Value="Visible" />
</MultiTrigger>
<Trigger Property="IsEnabled"
Value="False">
<Setter Property="Background"
Value="#686868" />
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsEnabled"
Value="False" />
<!--<Condition Property="ShowTextWhenDisabled"
Value="False" />-->
</MultiTrigger.Conditions>
<Setter Property="Visibility"
TargetName="mDisabledTextBlock"
Value="Visible" />
<Setter Property="Visibility"
TargetName="mValueStackPanel"
Value="Collapsed" />
</MultiTrigger>
<!-- trigger to flash the object when the textbox has an error -->
<Trigger Property="Validation.HasError"
Value="True">
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation BeginTime="00:00:00"
Duration="00:00:00.2"
From="0"
To="1"
Storyboard.TargetName="ErrorFlashObject"
Storyboard.TargetProperty="Opacity">
<DoubleAnimation.EasingFunction>
<PowerEase Power="2"
EasingMode="EaseIn" />
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
<DoubleAnimation BeginTime="00:00:00.2"
Duration="00:00:00.5"
From="1"
To="0"
Storyboard.TargetName="ErrorFlashObject"
Storyboard.TargetProperty="Opacity">
<DoubleAnimation.EasingFunction>
<PowerEase Power="2"
EasingMode="EaseIn" />
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
</Trigger>
<!-- trigger to flash the object when the textbox is selected -->
<EventTrigger RoutedEvent="FocusManager.GotFocus">
<BeginStoryboard>
<Storyboard>
<DoubleAnimation BeginTime="00:00:00"
Duration="00:00:00.2"
From="0"
To="1"
Storyboard.TargetName="FlashObject"
Storyboard.TargetProperty="Opacity">
<DoubleAnimation.EasingFunction>
<PowerEase Power="2"
EasingMode="EaseIn" />
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
<DoubleAnimation BeginTime="00:00:00.2"
Duration="00:00:00.5"
From="1"
To="0"
Storyboard.TargetName="FlashObject"
Storyboard.TargetProperty="Opacity">
<DoubleAnimation.EasingFunction>
<PowerEase Power="2"
EasingMode="EaseIn" />
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
【问题讨论】：
您能否添加一个完整的 XAML 示例？ 【参考方案1】：RelativeSource 绑定不会沿着您的 XML 前进，它们会沿着 Visual Tree 前进。这意味着您可以仅在您绑定的元素在该树中时使用它。
在这种情况下，您的DoubleValidationRule 不是 UIElement，并且它在可视化树中不是，因此RelativeSouce 在此规则上的绑定将失败。
不幸的是，在不知道您的DoubleValidationRule.MinMaxDependencyObject 的实现或目的的情况下，很难说您应该做什么。您可以通过更改验证规则的实现来绕过此限制。
一种可行的方法是，您可以通过 x:Name 值引用树中的元素
Minimum="Binding MinimumValue, ElementName=TheMinimumTarget
但这可能意味着您不能使用 Style 来执行此操作，因为每次使用都会（可能）绑定到表单上的不同元素。
查看您的编辑... Wat？您要将控件的文本绑定到控件的文本以附加验证规则吗？那是……我什至没有。
我建议对控件进行子类化以添加验证逻辑（例如，覆盖 Text 依赖属性的属性元数据），然后将您的模板应用于这种新类型。
【讨论】：
对，这是一种风格，所以我不能应用名称。 MinMaxDependencyObject 是一个简单的类，它继承具有最小值和最大值的 DependencyObject。它的唯一目的是让我可以对 DoubleValidationRule 使用绑定。你有什么建议吗？谢谢。以上是关于WPF 数据验证中的绑定失败的主要内容，如果未能解决你的问题，请参考以下文章