How to programmatically access a datagrid row details control

Okay, I figured out how to get this working I had to tweak the code that is posted in that MSDN article in the original question ....

DataGridRow row = (DataGridRow)(KeywordsGrid.ItemContainerGenerator.ContainerFromItem(KeywordsGrid.SelectedItem));

// Getting the ContentPresenter of the row details
DataGridDetailsPresenter presenter = FindVisualChild<DataGridDetailsPresenter>(row);

// Finding Remove button from the DataTemplate that is set on that ContentPresenter
DataTemplate template = presenter.ContentTemplate;
Button button = (Button)template.FindName("RemoveItemButton", presenter);

KeywordsGrid is the variable tied to my DataGrid. Notice in my call to FindVisualChild, I'm using a DataGridDetailsPresenter class instead of a ContentPresenter (this was the key... it forced the FindVisualChild method to iterate all the way through all the content presenters until I got to the one for the row details).

Use the DataGrid.LoadingRowDetails event! It is much more straight forward.

I found this here: How to change Text of TextBlock which is in DataTemplate of Row Details for each DataGrid Row Details?

Example:

xaml

<DataGrid.RowDetailsTemplate>
     <DataTemplate>
         <TextBlock x:Name="Test">Test</TextBlock>
         </DataTemplate>
</DataGrid.RowDetailsTemplate>

c#

private void dgVehicles_LoadingRowDetails(object sender, DataGridRowDetailsEventArgs e)
{
    TextBlock tbTest = e.DetailsElement.FindName("Test") as TextBlock;
    if (tbTest != null)
    {
        tbTest.Text = "Juhuu";
    }
}