Hello dear Iñaki Arenaza.
Thank you for your message.
Unfortunately, you really misunderstood me, so I apologize for my poor English.
Of course, the Name, Surname and E-mail as mandatory (necessary) attributes should be stored and processed directly in the Moodle database, and not be retrieved «on the fly» with each request from the LDAP catalog. 😉
My question, or more precisely, the request was directed to the fact that if the LDAP server authentication method (Sync Plus) is set for the user account and further it is assumed that the Name, Surname and E-mail will be automatically filled in (or synchronized) with LDAP
1) at the first user login to the System, or
2) as suggested by the LDAP server plugin (Sync Plus), directly during the creation of a user account manually by the Administrator,
then perhaps it is superfluous to control for the inadmissibility of empty values in the above attributes at the User Interface level (not in the Moodle Database)?
P.S. Our IT-company implements Moodle not in an educational institution, but in a business company - an airline, where the educational process has its own specific features and differs significantly from educational institutions. In particular, it is impossible to automatically create an account in Moodle when you first log into the System, filling in the missing user information from the LDAP. We have requirements, user accounts will only be created centrally by the Administrator.
really hope that my additional explanations will allow you to get constructive suggestions and / or solutions, including that this requires a complete redesign of the user input form to adapt it to LDAP (develop your own plugin).