Find Total of DataGrid Column - WPF C#

Hi, 

I have a WPF DataGrid (dgvTransactionData) and I have a column that has the total item price for each item. These will always be numeric values.

What I want to do is calculate the total of that column.

Here's what I have so far:

private string CalculateTotalPrice()
        {
            var finalTotalPrice = 0;

            foreach (DataRowView rv in dgvTransactionData.Items)
            {
                var rowCount = Convert.ToInt32(((DataTable) dgvTransactionData.ItemsSource).Rows.Count.ToString(CultureInfo.InvariantCulture));
                var terms = new int[rowCount];
                for (var rownum = 0; rownum <= rowCount; rownum++)
                {
                    terms[rownum] = Convert.ToInt32(rv.Row[rownum].ToString());
                }
                var numbers = new string[rowCount];

                finalTotalPrice += numbers.Sum(num => Convert.ToInt32(num));
            }
            return finalTotalPrice.ToString("C");
        }

I'm pretty sure it doesn't work on one column because I haven't specified what column to loop through.

Anyway it throws an exception on

                var rowCount = Convert.ToInt32(((DataTable) dgvTransactionData.ItemsSource).Rows.Count.ToString(CultureInfo.InvariantCulture));

An unhandled exception of type 'System.InvalidCastException' occurred in CheckoutPOS.exe

Additional information: Unable to cast object of type 'System.Data.DataView' to type 'System.Data.DataTable'.

Any thoughts,

Thanks for the help in advance

From, Nathaniel Peiffer