C# – WPF DataGrid – Databind to DataTable cell in CellTemplates DataTemplate

The bindings in the template don't work because the DataContext is a DataRowView from the DataTable.

One solution is to change your template to set the DataContext to the object you want (of type A), then all your bindings would work (Name, GroupName, IsSelected). To do that, you will need to make a converter and have your template use it.

The DataContext in the template, is bound to it's DataGridCell ancestor which is passed into the converter. From the cell, we can get the DataContext (DataRowView) and we can get the cell's Column. When we make the column in DataGrid_AutoGeneratingColumn, we set the column's SortMemberPath to e.PropertyName (the column's name in the datatable). In the converter, we lookup the object in the DataRowView.Row using the SortMemberPath as the index. We return this as the DataContext for the template.

Here is the implementation with a class A and class B. I added two columns of each class to my data table to show that it works with multiple instances.

MainWindow.xaml:

<Window x:Class="WpfApplication17.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:viewModel="clr-namespace:WpfApplication17"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <viewModel:DataRowViewConverter x:Key="drvc" />
        <DataTemplate x:Key="ATemplate">
            <RadioButton DataContext="{Binding RelativeSource={RelativeSource AncestorType=DataGridCell}, Converter={StaticResource drvc}}" Content="{Binding Path=Name}" GroupName="{Binding Path=GroupName}" IsChecked="{Binding Path=IsSelected}" />
        </DataTemplate>
        <DataTemplate x:Key="BTemplate">
            <CheckBox DataContext="{Binding RelativeSource={RelativeSource AncestorType=DataGridCell}, Converter={StaticResource drvc}}" Content="{Binding Path=FullName}" IsChecked="{Binding Path=IsChecked}" />
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <DataGrid AutoGenerateColumns="True" ItemsSource="{Binding Items}" AutoGeneratingColumn="DataGrid_AutoGeneratingColumn" CanUserAddRows="False">
        </DataGrid>
    </Grid>
</Window>

MainWindow.xaml.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApplication17
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public System.Data.DataTable Items { get; set; }

        public MainWindow()
        {
            InitializeComponent();

            System.Data.DataTable dt = new System.Data.DataTable();
            dt.Columns.Add("StringColumn", typeof(string));
            dt.Columns.Add("IntColumn", typeof(int));
            dt.Columns.Add("AColumn1", typeof(A));
            dt.Columns.Add("AColumn2", typeof(A));
            dt.Columns.Add("BColumn1", typeof(B));
            dt.Columns.Add("BColumn2", typeof(B));

            dt.Rows.Add(
                "TestString",
                123,
                new A() { Name = "A1", GroupName = "GroupName", IsSelected = true },
                new A() { Name = "A2", GroupName = "GroupName", IsSelected = false },
                new B() { FullName = "B1", IsChecked=true },
                new B() { FullName = "B2", IsChecked=false }
            );

            Items = dt;
            this.DataContext = this;
        }

        private void DataGrid_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
        {
            DataTemplate dt = null;
            if (e.PropertyType == typeof(A))
                dt = (DataTemplate)Resources["ATemplate"];
            else if (e.PropertyType == typeof(B))
                dt = (DataTemplate)Resources["BTemplate"];

            if (dt != null)
            {
                DataGridTemplateColumn c = new DataGridTemplateColumn()
                {
                    CellTemplate = dt,
                    Header = e.Column.Header,
                    HeaderTemplate = e.Column.HeaderTemplate,
                    HeaderStringFormat = e.Column.HeaderStringFormat,
                    SortMemberPath = e.PropertyName // this is used to index into the DataRowView so it MUST be the property's name (for this implementation anyways)
                };
                e.Column = c;
            }
        }
    }

    public class A
    {
        public string Name { get; set; }
        public string GroupName { get; set; }
        public bool IsSelected { get; set; }
    }

    public class B
    {
        public string FullName { get; set; }
        public bool IsChecked { get; set; }
    }

    public class DataRowViewConverter : IValueConverter
    {
        #region IValueConverter Members

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            DataGridCell cell = value as DataGridCell;
            if (cell == null)
                return null;

            System.Data.DataRowView drv = cell.DataContext as System.Data.DataRowView;
            if (drv == null)
                return null;

            return drv.Row[cell.Column.SortMemberPath];
        }

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

        #endregion
    }
}