.Net v4 DataGridTextColumn.IsReadOnly seems to be

Question

If I create a binding to the IsReadOnly property of the DataGridTextColumn, it does not actualize. If I set it through markup, it works.

<DataGridTextColumn IsReadOnly="{Binding IsReferenceInactive}"/> <!-- NOP --> 

<DataGridTextColumn IsReadOnly="True"/> <!-- Works as expected, cell is r/o -->

The IsReferenceInactive property is a DP and works fine (For testing purposes I've bound it to a checkbox, that worked)

Is this a known limitation?

Update

Uups, other than I wrote, there is a message in the output window:

System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=IsReferenceInactive; DataItem=null; target element is 'DataGridTextColumn' (HashCode=23836176); target property is 'IsReadOnly' (type 'Boolean')

Seems to be this one:

http://connect.microsoft.com/VisualStudio/feedback/details/530280/wpf-4-vs2010-datagrid-isreadonly-does-not-work-with-binding-to-boolean-property

Answer 1

DataGridColumns are not part of the visual tree, and don't participate in binding like this. The way I get around it is to use DataGridTemplateColumn.

<DataGridTemplateColumn>
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Path=myProperty}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
    <DataGridTemplateColumn.CellEditingTemplate>
        <DataTemplate>
            <TextBox IsEnabled="{Binding Path=myBool}" Text="{Binding Path=myProperty, Mode=TwoWay}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>

There are other workarounds, which I've found a bit too hackish, but they do work; to wit: http://blogs.msdn.com/b/jaimer/archive/2008/11/22/forwarding-the-datagrid-s-datacontext-to-its-columns.aspx

Answer 2

I've found a nice solution to use DataGridColumns with binding by using a MarkupExtension. This way Bindings with converters could be used: https://stackoverflow.com/a/27465022/9758687

Answer 3

If you like @codekaizen's solution but will have the look of a disabled TextBox, then this will do the trick:

<DataGridTemplateColumn>
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <TextBox IsEnabled="{Binding Path=myBool}" Text="{Binding Path=myProperty}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
    <DataGridTemplateColumn.CellEditingTemplate>
        <DataTemplate>
            <TextBox IsEnabled="{Binding Path=myBool}" Text="{Binding Path=myProperty, Mode=TwoWay}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>

Answer 4

Same as codekaizen but simpler:

<DataGridTextColumn>
  <DataGridTextColumn.CellStyle>
    <Style>
      <Setter Property="UIElement.IsEnabled" Value="{Binding IsEditable}" />
    </Style>
  </DataGridTextColumn.CellStyle>
</DataGridTextColumn>

Answer 5

The Binding of the DataGridTextColumn works only for the Text property, but not for the other properties of DataGridTextColumn.

Solution: DataGridTextColumn tells the DataGrid to create a TextBlock for every row and that column. You can define a style for TextBlock and link the Style with the Style.Key to the TextBlock of that column (ElementStyle).

Of course, the TextBlock needs now to find the object from the datalist. It can do that with a RelativeSource Binding with the AncestorType=DataGridRow. The DataGridRow then provides access to the object.

Something like this:

<Window.Resources>
  <Style x:Key="IsReadOnlyStyle" TargetType="TextBlock">
    <Setter Property="IsReadOnly" 
      Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}, 
      Path =Item.NoOutput/>
  </Style>
</Window.Resources>

<DataGrid>
  <DataGrid.Columns>
    <DataGridTextColumn Header="Value" Width="*" Binding="{Binding Value}" ElementStyle="{StaticResource IsReadOnlyStyle}"/>
</DataGrid.Columns>

Complicated right ? I recommend you to read my detailed article about datagrid formatting at: http://www.codeproject.com/Articles/683429/Guide-to-WPF-DataGrid-formatting-using-bindings?msg=5037235#xx5037235xx

Good luck, you need it :-)

Answer 6

I found this solution which allows you to bind to data when the DataContext is not inherited: http://www.thomaslevesque.com/2011/03/21/wpf-how-to-bind-to-data-when-the-datacontext-is-not-inherited/

Add the BindingProxy class Thomas wrote and add this resource to your DataGrid:

<DataGrid.Resources>
    <local:BindingProxy x:Key="proxy" Data="{Binding}" />
</DataGrid.Resources>

Now you can bind to your DataContex via the Data property of the BindingProxy just as you would expect.

<DataGridTextColumn Header="Price"
                    Binding="{Binding Price}"
                    IsReadOnly="{Binding Data.LockFields, Source={StaticResource proxy}}"/>