wpf 无法找到引用“RelativeSource FindAncestor”的绑定源
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Cannot find source for binding with reference 'RelativeSource FindAncestor'
提问by Hodaya Shalom
I get this error:
我收到此错误：
Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.UserControl', AncestorLevel='1''
on this Binding:
在此绑定上：
<DataGridTemplateColumn Visibility="{Binding DataContext.IsVisible, RelativeSource={RelativeSource AncestorType={x:Type UserControl}},Converter={StaticResource BooleanToVisibilityConverter}}">
The ViewModel is sitting as DataContext in UserControl. The DataContext of the DataGrid (sitting in UserControl) is property within the ViewModel, in ViewModel I have a variable that says whether to show a certain line or not, its binding fails, why?
ViewModel 位于 UserControl 中的 DataContext。DataGrid 的 DataContext（位于 UserControl 中）是 ViewModel 中的属性，在 ViewModel 中我有一个变量表示是否显示某行，其绑定失败，为什么？
Here my property :
这是我的财产：
private bool _isVisible=false;
public bool IsVisible
{
get { return _isVisible; }
set
{
_isVisible= value;
NotifyPropertyChanged("IsVisible");
}
}
When it comes to the function: NotifyPropertyChanged the PropertyChanged event null - mean he failed to register for the binding.
当涉及到函数时：NotifyPropertyChanged PropertyChanged 事件 null - 意味着他未能注册绑定。
It should be noted that I have more bindings to ViewModel in such a way that works, here is an example:
应该注意的是，我以这种有效的方式对 ViewModel 进行了更多绑定，这是一个示例：
Command="{Binding DataContext.Cmd, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"
回答by Cameron MacFarland
DataGridTemplateColumnis not part of the visual or logical tree, and therefore has no binding ancestor (or any ancestor) so the RelativeSourcedoesn't work.
DataGridTemplateColumn不是可视化或逻辑树的一部分，因此没有绑定祖先（或任何祖先），因此RelativeSource不起作用。
Instead you have to give the binding the source explicitly.
相反，您必须明确地为绑定提供源。
<UserControl.Resources>
<local:BindingProxy x:Key="proxy" Data="{Binding}" />
</UserControl.Resources>
<DataGridTemplateColumn Visibility="{Binding Data.IsVisible,
Source={StaticResource proxy},
Converter={StaticResource BooleanToVisibilityConverter}}">
And the binding proxy.
和绑定代理。
public class BindingProxy : Freezable
{
protected override Freezable CreateInstanceCore()
{
return new BindingProxy();
}
public object Data
{
get { return (object)GetValue(DataProperty); }
set { SetValue(DataProperty, value); }
}
// Using a DependencyProperty as the backing store for Data.
// This enables animation, styling, binding, etc...
public static readonly DependencyProperty DataProperty =
DependencyProperty.Register("Data", typeof(object),
typeof(BindingProxy), new UIPropertyMetadata(null));
}
学分。
