Usernames should not be case-sensitive when logging in

[shane-tang]

Affected Platforms

• All (server issue)

Description

Today, you cannot register as USERNAME if someone else already registered as username. Most of the codebase now enforces case-insensitive username uniqueness. Account login is one of the few places that is still case-sensitive to usernames. If you registered as Username then you cannot log in as username. This is problematic for a couple of reasons:

• Users may not be aware of the exact casing they used for their usernames during initial registration
• Users typing on a phone or smartwatch are less likely to be precise about their capitalizations.
  • For example, phones and wearables auto-capitalize the first letter of an input field by default, which may cause confusion when a user's login fails because their username starts with a lowercase character

Caveats

Even though new account usernames cannot collide with existing account usernames, I acknowledge there's a chance that username collisions might exist from before this constraint was implemented. We can't naively say that all usernames are currently case-insensitively unique. Unless there has been some server backfill to address this, there are undoubtedly a small handful of colliding usernames. I'd bet there are users with the usernames bob and Bob.

However, it should be possible to use case-insensitive logins when there is exactly one user with the "same" username, then fallback to case-sensitive logins when there are multiple users with the "same" username.

For example:

• If I am the only user with some permutation of the username Unique then I should be able to log in using unique or UNIQUE or uNiQuE.
• If there is a user named collision and another user named COLLISION, then both of these users should follow the existing login behavior and should only be able to log in using their case-sensitive username. A login attempt with the username Collision should always fail because it's ambiguous which user model should be retrieved.

Additional Notes

The reason I'm posting this as a GitHub issue is because I already have a PR fix up.

[bilalshaikh292]

heyy I would like to contribute ?