Grid in BatchEdit mode must be one of the most useful features in some serious industry-level web applications. It comes quite naturally, that the data in the grid must be often extensively validated, and in many cases the client side validation is simply not enough. In our case, we had to use BatchEditing mode and we had to validate user-entered values serverside (due to complex rules, external data to validation against in real time and safety/security of the validation itself). 

Documentation states that BatchEdit does not support ServerSide validation. This makes BatchEdit mode mostly useless for some serious use, which is a pitty. But how much is needed to do so? The only thing we need is, when processing RadGrid_BatchEditCommand, to send the unsaved changes back to the client (overwrite the old values which would come from the database via NeedDataSource) and mark the changed cells as "EDITED" or "CHANGED", because:

a. We have to make sure, that the unsaved rows from the session variable will always come up, next time the user hits the Save changes button, in the BatchEditCommand in Hashtable newValues = command.NewValues; This is because only rows, which RadGrid understand as changed by user-client side, will come up in the newValues HashTable. In case that the user changed, in the first server-side roundtrip, rows 1 and 2, rows 1 and 2 would be saved to the session variable and they would be presented to the user, but in the second round user would not change rows 1 and 2 but change only row 3, it would be only row 3 which would come up in RadGrid1_BatchEditCommand the newValues Hashtable, and we would never get previous, still unsaved, changes

b. in case the user goes to the next page of the grid, using paging arrows in the grid, the grid normally warns about unsaved changes and prevents user from going to the next page, if there are any unsaved changes. If our changed rows from the session are not marked as EDITED, the grid would never ask this and would proceed to the next page, losing users changes.

We were fighting to make this work via some session variables, etc, but then Doncho from Telerik support sent us this simple solution. I think many would be happy if you could add it to the next release, so it is supported out of the box. Attaching files from Doncho, which give an ide to the solution

Thank you.