I created a RadDataGrid and a custom edit command as described in the edit commands doc. However the Execute method is never called.
What else do I need to do to fire a commit edit command?
This depends on what editing approach is being used, you can find the description of when the commit occurs here - DataGrid Edit Operation.
In this case of inline editing, the Commit is invoked when the row is done being edited (i.e. the user leaves the focus of the row).
In case it is useful, I've attached an example for you, here's a screenshot at runtime to verify that the Execute in invoking as expected:
You could also use DataGridUserCommand instead of a custom class and bind it to a Relay or DelegateCommand in the view model. See the DataGrid Commands article Example.
Lance | Manager - Technical Support