Challenge 2 / 2

You decide to switch the “unique identifier” from email to a username. What else do you need to change so logging in can still work?

Only rename the email property to username in User — Symfony figures out the rest automatically.

Update security.yaml so the user provider looks users up by username, and update getUserIdentifier() in User to return the username.

Nothing in Symfony: you just need to clear the cache and the firewall will magically start using username.

Only update the database unique constraint — Symfony doesn’t care what getUserIdentifier() returns.