wpf 绑定错误：无法找到引用“RelativeSource FindAncestor”的绑定源
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原文地址: http://stackoverflow.com/questions/34591499/
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Binding Error : Cannot find source for binding with reference 'RelativeSource FindAncestor
提问by A K P
I have a customized Textbox which has some property SelfPropertyInfo(which further has some property like IsValid and RuleDescription).
我有一个自定义的文本框，它有一些属性 SelfPropertyInfo（它还有一些像 IsValid 和 RuleDescription 这样的属性）。
I am trying to add below style on every Textbox of this type.
我试图在这种类型的每个文本框上添加以下样式。
<Style TargetType="{x:Type CustomControls:TextBox}">
<Setter Property="Height" Value="22"/>
<Setter Property="Margin" Value="2,2,2,2"/>
<Style.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Background" Value="DarkGray" />
</Trigger>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=SelfPropertyInfo.IsValid}" Value="False">
<Setter Property="BorderBrush" Value="Red"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="ToolTip" >
<Setter.Value>
<ToolTip >
<TextBlock Foreground="Red" Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type CustomControls:TextBox},AncestorLevel=2},Path=SelfPropertyInfo.RuleDescription}"/>
</ToolTip>
</Setter.Value>
</Setter>
</DataTrigger>
</Style.Triggers>
</Style>
In above code I am not getting Tooltip Text. (Result of below code)
在上面的代码中，我没有收到工具提示文本。（以下代码的结果）
<TextBlock Foreground="Red" Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type CustomControls:TextBox},AncestorLevel=2},Path=SelfPropertyInfo.RuleDescription}"/>
I am getting below error:
我收到以下错误：
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='CustomControls.TextBox', AncestorLevel='2''. BindingExpression:Path=SelfPropertyInfo.RuleDescription; DataItem=null; target element is 'TextBlock' (Name=''); target property is 'Text' (type 'String')
System.Windows.Data 错误：4：无法找到引用“RelativeSource FindAncestor、AncestorType='CustomControls.TextBox'、AncestorLevel='2'”的绑定源。BindingExpression:Path=SelfPropertyInfo.RuleDescription；数据项=空；目标元素是 'TextBlock' (Name=''); 目标属性是“文本”（类型“字符串”）
Can anybody suggest the mistake I did in Text binding?
有人可以建议我在文本绑定中犯的错误吗？
Note: I can't change the way Tooltip is added :(
注意：我无法更改添加工具提示的方式:(
回答by A K P
First of all I would like to say thanks to nkoniishvtfor this link. It helped me to understand the problem. By using below code it worked as expected:
首先我要感谢nkoniishvt提供这个链接。它帮助我理解了这个问题。通过使用下面的代码，它按预期工作：
<Style TargetType="{x:Type CustomControls:TextBox}">
<Setter Property="Height" Value="22"/>
<Setter Property="Margin" Value="2,2,2,2"/>
<Style.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Background" Value="DarkGray" />
</Trigger>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=SelfPropertyInfo.IsValid}" Value="False">
<Setter Property="BorderBrush" Value="Red"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Tag" Value= "{Binding RelativeSource={RelativeSource Self}}"/>
<Setter Property="ToolTip">
<Setter.Value>
<ToolTip Height="28" Background="Red" DataContext="{Binding RelativeSource={RelativeSource Self},Path=PlacementTarget.Tag}">
<TextBlock Foreground="White" Text="{Binding Path=SelfPropertyInfo.RuleDescription}"/>
</ToolTip>
</Setter.Value>
</Setter>
</DataTrigger>
</Style.Triggers>
</Style>
