Binding with ElementName does not work

Question

Here is the 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>

Binding returns error: System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element.

What do I miss?

Update:

Here is the answer: 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.

Update 2: Good article about DataGrid's caveats: http://blogs.msdn.com/b/vinsibal/archive/2009/04/07/5-random-gotchas-with-the-wpf-datagrid.aspx

I don't think `ElementName` works *within* the same element. — ChrisF, Nov 01 '11 at 09:11
Here is the answer: 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. — Pavel Voronin, Nov 01 '11 at 09:39
yet another funny bug that proves the only thing WPF is good for is writing tutorials, this technology is driving me crazy. — lot, Jan 27 '21 at 18:13

score 1 · Accepted Answer · edited May 23 '17 at 11:46

1

Binding on DataGridColumn for Header abd Visibility properties needs special treatment...

See this...

Bind datagrid column visibility MVVM

edited May 23 '17 at 11:46

Community

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1

answered Nov 01 '11 at 10:11

WPF-it

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Yep this worked for me too. `ProxyElement` approach is a very good hack. :-) – Nov 01 '11 at 10:52

Emond · Answer 2 · 2011-11-01T10:39:28.030

0

If you are interested in the Count property of the object that is referred to in the DataContext you try and use regular databinding:

<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>

EDIT

Apparently the columns of a datagrid are not part of the Visual Tree So using ElementName and RelativeSource will not work. Perhaps you should add the property to the object the column is bound to.

edited Nov 01 '11 at 10:39

answered Nov 01 '11 at 09:29

Emond

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I need the DataContext of DataGrid. – Pavel Voronin Nov 01 '11 at 09:37
@voroninp - Did you try RelativeSource Ancestor? – Emond Nov 01 '11 at 09:40
@voroninp - I added to my answer – Emond Nov 01 '11 at 10:39

Binding with ElementName does not work

2 Answers2