用的ElementName绑定不起作用

Question

这里是XAML：

<DataGrid Grid.Column="0" AutoGenerateColumns="False" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" ItemsSource="{Binding Path=Columns}" 
       x:Name="ColumnsGrid" RowHeaderWidth="0"> 
     <DataGrid.Columns> 
      <DataGridTextColumn Width="*" Binding="{Binding Path=Header}" 
           Header="{Binding ElementName=ColumnsGrid, Path=DataContext.Count, StringFormat=Columns ({0}), diag:PresentationTraceSources.TraceLevel=High}"/> 
     </DataGrid.Columns> 
    </DataGrid> 

绑定返回错误：System.Windows.Data错误：2：找不到理事FrameworkElement的或FrameworkContentElement上的目标元素。

我错过了什么？

更新：

下面是答案： http://blogs.msdn.com/b/jaimer/archive/2008/11/22/forwarding-the-datagrid-s-datacontext-to-its-columns.aspx

What is happening here? The Columns collection is just a property in the Datagrid; this collection is not in the logical (or visual) tree, therefore the DataContext is not being inherited, which leads to there being nothing to bind to.

更新2： 约DataGrid的告诫好文章：http://blogs.msdn.com/b/vinsibal/archive/2009/04/07/5-random-gotchas-with-the-wpf-datagrid.aspx

Answer 1

绑定上DataGridColumn为Header ABD Visibility性质需要特殊处理...

看到这个...

Bind datagrid column visibility MVVM

Answer 2

如果你有兴趣在计数DataContext中引用的对象的属性您尝试使用常规数据绑定：

<DataGrid Grid.Column="0" AutoGenerateColumns="False" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" ItemsSource="{Binding Path=Columns}" 
      x:Name="ColumnsGrid" RowHeaderWidth="0"> 
    <DataGrid.Columns> 
     <DataGridTextColumn Width="*" Binding="{Binding Path=Header}" 
          Header="{Binding Path=Count, StringFormat=Columns ({0}), diag:PresentationTraceSources.TraceLevel=High}"/> 
    </DataGrid.Columns> 
</DataGrid> 

编辑

显然the columns of a datagrid are not part of the Visual Tree 因此，使用的ElementName和的RelativeSource将无法正常工作。 也许你应该将该属性添加到列绑定到的对象。