in my WPF there is a DataGrid which columns are auto-generated. The data is loaded from extern, so the column names are known at runtime. For certain columns, i display a button inside the column. Only when clicked onto the button, i load other data and display it inside the RowDetails of the outer DataGrid. Then, the inner DataGrid is loaded again – maybe with other buttons. This is repeated for ever.

I want to do this with a DataTemplateSelector. This is my current .xaml code:

<Window.Resources>
    <local:DynamicDataTemplateSelector x:Key="dynamicTemplateSelector" />
</Window.Resources>

<DataGrid ItemsSource="{Binding DataTable1.DefaultView}" AutoGenerateColumns="True"
                        AutoGeneratingColumn="DataGrid_AutoGeneratingColumn" CanUserAddRows="False>
    <DataGrid.RowDetailsVisibilityMode>Collapsed</DataGrid.RowDetailsVisibilityMode>
    <DataGrid.RowDetailsTemplateSelector>
        <StaticResource ResourceKey="dynamicTemplateSelector"/>
    </DataGrid.RowDetailsTemplateSelector>
</DataGrid>

DataGrid_AutoGeneratingColumn(sender, e) calls HandlerDgAutoGeneratingColumn(sender, e) In this method i declare an event when the button inside the cell is clicked. DataTable1 is a DataTable with geter/seter, i added the RaisePropertyChanged Event for MVVM.

In my DataTemplateSelector i build a new DataGrid if there is one column that contains a button. The inner DataGrid is fully loaded and correctly bound. I build the DataGrid visually in the correct style. But: The AutoGeneratedEvent is never fired. The breakpoints in DataGrid_AutoGeneratingColumnTempl are never reached. I cannot figure out, why.

This is my current class DataTemplateSelector:

public class DynamicDataTemplateSelector : DataTemplateSelector
  {
    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
      if (item is DataRowView dataRowView)
      {
        foreach (var column in dataRowView.DataView.Table.Columns.Cast<DataColumn>())
        {
          if (column.DataType == typeof(DataTable))
          {
            var template = new DataTemplate();
            var dataGridFactory = new FrameworkElementFactory(typeof(DataGrid));

            // Binding ItemsSource to the inner DataTable's DefaultView
            dataGridFactory.SetBinding(DataGrid.ItemsSourceProperty, new Binding($"{column.ColumnName}.DefaultView"));
            dataGridFactory.SetValue(DataGrid.AutoGenerateColumnsProperty, true);

            // Setting CanUserAddRows to False
            dataGridFactory.SetValue(DataGrid.CanUserAddRowsProperty, false);

            // Setting RowDetailsVisibilityMode to Collapsed
            dataGridFactory.SetValue(DataGrid.RowDetailsVisibilityModeProperty, DataGridRowDetailsVisibilityMode.Collapsed);

            // Adding the AutoGeneratingColumn event
            dataGridFactory.AddHandler(DataGrid.LoadedEvent, new RoutedEventHandler((sender, args) =>
            {
              var dataGrid = sender as DataGrid;
              if (dataGrid != null)
              {
                // This code is executed
                dataGrid.AutoGeneratingColumn += DataGrid_AutoGeneratingColumnTempl;
              }
            }));

            // Setting up RowDetailsTemplateSelector for recursive templates
            dataGridFactory.SetValue(DataGrid.RowDetailsTemplateSelectorProperty,
                new DynamicResourceExtension("dynamicTemplateSelector"));


            template.VisualTree = dataGridFactory;
            return template;
          }
        }
      }
      return base.SelectTemplate(item, container);
    }

    private void DataGrid_AutoGeneratingColumnTempl(object sender, DataGridAutoGeneratingColumnEventArgs e)
    {
      //This code is never reached.

      // Handle the AutoGeneratingColumn event to customize columns
      MainWindow mainWindow = Application.Current.MainWindow as MainWindow;
      if (mainWindow != null)
      {
        mainWindow.HandlerDgAutoGeneratingColumn(sender, e);  
      }
    }
  }

I tried asking this question to ChatGPT with no success. I expect DataGrid_AutoGeneratingColumnTempl to be called. I should be able to see 3 inner DataGrids. But i only see one where the buttons in the third columns are not displayed: Status Quo. There should be buttons in the “InnerDataTable” column.