Duplicate username does not consider title case

[sabachanna]

I was able to register two accounts with usernames sabachanna and Sabachanna. It did not give duplicate username error. It is not able to capture lower case or title case differences. I tried to look into it but mongodb does not support case-insensitive queries.

Should we store the username as all capital or all lower in mongodb and then, on registration, convert the given username to upper case to see if duplicate is already available or not. Should we consider this on presentation layer?

[honkskillet]

I store both an all lower cased version of the username and a mixed up and lower case (for display purposes). It seemed like the easiest solution.

[Daniel-Xu]

you can add custom validation in user model

[jeffbuhrt]

Best security practice says user names should be case insensitive.
https://www.owasp.org/index.php/Authentication_Cheat_Sheet

User IDs
Make sure your usernames/userids are case insensitive. User 'smith' and user 'Smith' should be the same user.