WPF 相对源 - 找不到与引用绑定的源
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WPF Relative source- Cannot find source for binding with reference
提问by Mateusz Dembski
have you ever have a problem like this:
你有没有遇到过这样的问题：
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.UserControl', AncestorLevel='1''. BindingExpression:Path=DataContext; DataItem=null; target element is 'ContextMenu' (Name=''); target property is 'DataContext' (type 'Object')
Code:
代码：
<ContextMenu DataContext="{Binding Path=DataContext, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}"
Context Menu is in the:
上下文菜单位于：
ListBox-> ListBoxItemTemplate -> DataGrid -> DataGrid.ContextMenu
I have also another Binding in ListBox control, that works with no problems at all.
我在 ListBox 控件中还有另一个 Binding，它完全没有问题。
回答by Mateusz Dembski
The solution:
解决方案：
1) Set Tag property on ContextMenu owner to DataContext you wanted. 2) Set DataContext of ContextMenu to
1) 将 ContextMenu 所有者的 Tag 属性设置为您想要的 DataContext。2）将ContextMenu的DataContext设置为
DataContext="{Binding PlacementTarget, RelativeSource={RelativeSource Self}}
3) Bind your elements like this:
3）像这样绑定你的元素：
Name_Of_Property="{Binding Tag.Name_Of_Property}"
回答by blindmeis
context menu is not part of the visual tree, so you use PlacementTarget within your binding
上下文菜单不是可视化树的一部分，因此您可以在绑定中使用 PlacementTarget
<ContextMenu DataContext="{Binding Path=PlacementTarget.DataContext, RelativeSource=Self}" />
this would use the DataContext of the DataGrid
这将使用 DataGrid 的 DataContext
