Simple way to display row numbers on WPF DataGrid

Question

I just want to display row numbers in the left-most column of my DataGrid. Is there some attribute to do this?

Keep in mind, this isn't a primary key for my table. I don't want these row numbers to move with their rows when a column is sorted. I basically want a running count. It doesn't even need to have a header.

Answer 1

Using attached properties, full source here.

using System.Windows;
using System.Windows.Controls;

public static class Index
{
    private static readonly DependencyPropertyKey OfPropertyKey = DependencyProperty.RegisterAttachedReadOnly(
        "Of",
        typeof(int),
        typeof(Index),
        new PropertyMetadata(-1));

    public static readonly DependencyProperty OfProperty = OfPropertyKey.DependencyProperty;

    public static readonly DependencyProperty InProperty = DependencyProperty.RegisterAttached(
        "In",
        typeof(DataGrid),
        typeof(Index),
        new PropertyMetadata(default(DataGrid), OnInChanged));

    public static void SetOf(this DataGridRow element, int value)
    {
        element.SetValue(OfPropertyKey, value);
    }

    public static int GetOf(this DataGridRow element)
    {
        return (int)element.GetValue(OfProperty);
    }

    public static void SetIn(this DataGridRow element, DataGrid value)
    {
        element.SetValue(InProperty, value);
    }

    public static DataGrid GetIn(this DataGridRow element)
    {
        return (DataGrid)element.GetValue(InProperty);
    }

    private static void OnInChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var row = (DataGridRow)d;
        row.SetOf(row.GetIndex());
    }
}

Xaml:

<DataGrid ItemsSource="{Binding Data}">
    <DataGrid.RowStyle>
        <Style TargetType="{x:Type DataGridRow}">
            <Setter Property="dataGrid2D:Index.In" 
                    Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" />
        </Style>
    </DataGrid.RowStyle>

    <DataGrid.RowHeaderStyle>
        <Style TargetType="{x:Type DataGridRowHeader}">
            <Setter Property="Content" 
                    Value="{Binding Path=(dataGrid2D:Index.Of), 
                                    RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}}" />
        </Style>
    </DataGrid.RowHeaderStyle>
</DataGrid>