I am working on Enterprise online application. Rather than adding user information by using conventional form filling concept, client has asked us to provide bulk user list upload option in which admin user can add 'n' number of users in a single shot. The issue is, some fields are mandatory and some of them or not. While uploading user details as excel, csv format, how can validate them as conventional form fields does? I understand that would be better to provide pre-defined template to user in which user can fill-up the respective details and upload them. After uploading the excel/csv files into the application validation has to be happened on screen.
Let's assume, if any of mandatory fields are missing in the uploaded document, how can we update them rather than updating the same file in local system and upload them again.
If any best practices are available, really appreciated.
Thanks in advance.