How to do get this CRUD code to work on WPF DataGrid?

Question

I'm writing CRUD code for the WPF Datagrid.

In the TheDataGrid_CellEditEnding method below:

• how do I get the original text before the user made the change?
• I need the original text to be able to change the customer and save it back to the database with _db.SubmitChanges()

Here's the full solution with database if anyone wants to experiment with this:

http://www.tanguay.info/web/download/testDataGrid566northwindDatagrid.zip

XAML:

<toolkit:DataGrid x:Name="TheDataGrid" 
                  AutoGenerateColumns="True"
                  CellEditEnding="TheDataGrid_CellEditEnding"/>

code-behind:

private void TheDataGrid_CellEditEnding(object sender, Microsoft.Windows.Controls.DataGridCellEditEndingEventArgs e)
{
    //get the original text
    Customer customer = e.Row.Item as Customer;
    string customerID = customer.CustomerID;
    int displayIndex = (int)e.Column.DisplayIndex; // e.g. equals 4 when user edits the 5th column

    //HOW TO I GET THE ORIGINAL TEXT? THERE IS NO FIELDS METHOD IN THE LINQ-TO-SQL CLASSES
    string originalText = customer.Fields[displayIndex].value.ToString();

    //get the changed text
    TextBox changedTextBox = e.EditingElement as TextBox;
    string changedText = changedTextBox.Text;

    //inform user
    Message.Text = String.Format("cell was changed from {0} to {1}", originalText, changedText);

    //I NEED TO CHANGE THE CUSTOMER WITH THE ABOVE TEXT
    //BEFORE I SAVE IT BACK HERE
    _db.SubmitChanges();
}

Answer 1

Why do you need the original text? Is it to display some informational message?

In your case, you seem to be binding the datagrid to your LinqToSQL objects. This means that the Customer object the row is bound to is already updated and all you need to do is call SubmitChanges().

Answer 2

I found the samples in this blog very helpful http://blogsprajeesh.blogspot.com/2009/03/blog-post.html

It explains sorting using the collection and grid events.