id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
29397	Username validation should be handled at the model level on object creation.	Andrew Carl	nobody	"I have a rather large django system that conglomerates users from a bunch of systems into a single platform. In order to prevent duplicate usernames, I am constructing usernames like: <username>|<previous_system_id>. I am able to successfully create and modify the user object with direct calls to the database. However, attempting to modify another username field in the admin site returns a validation error. I have attempted to overwrite this form-level validation like so:
{{{
admin.site.unregister(User)
username_field = forms.RegexField(label=""Username"", max_length=150,
    regex=r'^.+$',
    help_text = ""Required. 30 characters or fewer. Letters, digits and ""
                      ""@/./+/-/_/| only."",
    error_messages = {
            'invalid': ""This value may contain only letters, numbers and ""
                         ""@/./+/-/_/| characters.""})

class MyUserCreationForm(UserCreationForm):
    username = username_field

class MyUserChangeForm(UserChangeForm):
    username = username_field

@admin.register(User)
class MyUserAdmin(UserAdmin):
    add_form = MyUserCreationForm
    form = MyUserChangeForm
}}}

This, however will return the error:
 This value may contain only letters, numbers and @/./+/-/_/| characters.

This leads me to believe that my user admin form is correctly being overridden, as my custom error message is displayed. I am currently able to modify and save my user model by setting the 'username' field to be read only. 

The fact that I am able to save on the out of the box user model with an ""invalid"" character, but then have the stock admin site break I would consider unexpected behavior. This would be acceptable if the form validator was able to be overridden or if I was thrown an exception on object creation."	Bug	closed	contrib.admin	1.11	Normal	invalid			Unreviewed	0	0	0	0	0	0