Make AuthenticationForm use the username length from the user model

[Ramin Farajpour Cami]

AuthenticationForm has a hardcoded max_length=254 (#19130). It might be able to use the max length from the user model with something like: self.fields['username'].max_length = UserModel._meta.get_field(UserModel.USERNAME_FIELD).max_length in AuthenticationForm.__init__().

[Tim Graham]

The suggestion doesn't account for custom user models and undoes #19130 (you might try using git blame to investigate history next time).

If the current situation is problematic for you, perhaps there would be some value in setting the max length based on the custom user model ​as Claude suggested .

[Ramin Farajpour Cami]

User model use max_length=150,also in add user form set 150,
What your means "value setting the max length based on the custom user model"?

[Tim Graham]

​Custom user models may have a username with length other than 150, that's why using that value isn't appropriate. We might be able to use that with something like this: self.fields['username'].max_length = UserModel._meta.get_field(UserModel.USERNAME_FIELD).max_length.

[Ramin Farajpour Cami]

​PR

[Andrey Kuzminov]

Can I take this ticket or is it still Ramin's?

[Ramin Farajpour Cami]

Yes, please assign to you

[Lucas Connors]

​PR

[Lucas Connors]

Sorry for the spam. I thought unchecking and rechecking would automatically find the PR on Github. This is it here:
​https://github.com/django/django/pull/8925

[Tim Graham <timograham@…>]

In d2333912:

Refs #19130 -- Added a test for AuthenticationForm.username max_length.

This will be a more useful regression test after refs #27515.

[Tim Graham <timograham@…>]

In 5ceaf146:

Fixed #27515 -- Made AuthenticationForm's username field use the max_length from the model field.

Thanks Ramin Farajpour Cami for the report.