Hello,
Since the data is already available to you on the server, perhaps you may have a look at the Server Export demo at:
https://demos.telerik.com/aspnet-mvc/grid/server-export
If you look at the .cshtml file, the button click sends only the columns configuration to the backend:
Then, change tab and you will see that the columns received from the client are used to build the spreadsheet on the server and are parsed to a list of the ExportColumnSettings class:
This is almost identical to the demo I referenced in my previous response, where the model is mapped to a custom class:
https://github.com/telerik/ui-for-aspnet-mvc-examples/blob/master/grid/grid-dpl-integration/GridExcelSpreadProcessing/Controllers/StreamController.cs#L20
Both of the projects are available to you and both are runnable so you may debug them and put breakpoints where desired - the one in the repository is open to the public and the one in our online demos is part of our distribution:
https://www.telerik.com/account/product-download?product=KENDOUIMVC
Regards,
Alex Hajigeorgieva
Progress Telerik