username
Required. 150 characters or fewer. Usernames may contain alphanumeric, _, @, +, . and - characters.
The max_length should be sufficient for many use cases. If you need a longer length, please use a custom user model. If you use MySQL with the utf8mb4 encoding (recommended for proper Unicode support), specify at most max_length=191 because MySQL can only create unique indexes with 191 characters in that case by default.
Usernames and Unicode Django originally accepted only ASCII let