Summary rows in Datagrid with multiple groups

Sometime back I posted one way to show the Summary/Totals in the group header and be able to resize individual columns when the columns are resized. That method has a limitation of not supporting nested groups. we can extend the same method to support multiple groups

Here are the steps.
we will start with what we had like in the previous sample.
1. we will add 1 GroupHeader style for each group we have. In my sample all the GroupHeader styles are same. One important change is there is a stackpanel in the GroupHeader named “ghsp” which hosts all the columns in the GroupHeader. we will add a Tag attribute and give a value of  “n-1” when  “n” is the number of groups in the datagrid. if you have 3 groups then there will be 3 group header styles and Tag attribute  will be 2, 1, 0. This is how we can differentiate the different level group headers

2. The next change is in the Resize method. ” * 20″ is for resizing the column with groupname in the group header, 20 is roughly the size of indentation for each group (could be different if you change defaults in the template)

void Resize()
        {
            headers = datagrid1.GetChildrenByType<StackPanel>().Where(x => x.Name == “ghsp”).ToList();
            headers.ForEach(x =>
            {                
               (x.Children[0] as DataGridCell).Width = dghc.Children[1].RenderSize.Width + (Int32.Parse(x.Tag.ToString()) * 20) ;

                for (int i = 2; i < dghc.Children.Count – 2; i++)                                   
                    (x.Children[i – 1] as DataGridCell).Width = dghc.Children[i].RenderSize.Width;
               
            });
          
        }

3.  In the converter we have to change the way we get the totals from the CollectionViewGroup

private decimal GetProductTotal(CollectionViewGroup cvg)
        {
            decimal total = 0;
            int counter = 0;
            while (counter < cvg.Items.Count)
            {
                if (cvg.Items[counter] is CollectionViewGroup)
                    total += GetProductTotal(cvg.Items[counter] as CollectionViewGroup);
                else
                    total = (cvg.Items as IEnumerable<object>).Sum(x => (x as Product).Total);

                counter++;
            }
            return total;
        }

you can download the code from here