To initialize DataRow’s default values handle InitNewRow event of the required ASPxGridView control and initialize the default values by using e.NewValues dictionary in the following manner:
The issue occurs in Batch Edit Mode, because in this mode an empty invisible row is created and used for further grid editing. Since the Eval method returns a value type of an object, your attempt to call the ToString() method to the null value can lead to an exception. If you remove this conversion and use <%# […]
The following code shows how to group by two columns (“Country” and “City”).