Question

I have a DataGrid with DataGridTemplateColumns. In the TemplateColumn, I use a DataTrigger which works fine. It retrieves the Item Count from the DataGrid parent.

<DataGridTemplateColumn>                                                         
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
             ...
             <!-- this works fine! -->
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource FindAncestor,
                AncestorType={x:Type DataGrid}}, Path=Items.Count}" Value="1">
                    ...
             </DataTrigger>
          </DataTemplate>

Is it possible, to retrieve the current RowIndex in which the template is placed ?
I think that it is possible to bind to the current DataGridRow. A Binding Path of “GetIndex()” won’t be supported, like:

<DataTrigger Binding="{Binding RelativeSource={RelativeSource FindAncestor, 
    AncestorType={x:Type DataGridRow}}, Path=GetIndex()}" Value="0"> <!-- error: GetIndex() -->

Is there an alternative, to bind to DataGridRow.GetIndex() from xaml ?

Answer 1

You can only bind to Properties and not methods of an object. You need to use a IValueConverter in case you want to bind to method –

public class MyConverter : DependencyObject, IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, 
                             System.Globalization.CultureInfo culture)
    {
        return (value as DataGridRow).GetIndex();
    }

    public object ConvertBack(object value, Type targetType, object parameter,
                               System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

and bind it like this –

<DataTrigger Binding="{Binding RelativeSource={RelativeSource FindAncestor, 
                        AncestorType={x:Type DataGridRow}},
                        Converter={StaticResource MyConverter}}"
            Value="0">