django alphanumeric validator not work

Question

i try to force the user to use only alphanumeric characters in a certain

field so i wrote the following code in the User model:

alphanumeric = RegexValidator(r'^[0-9a-zA-Z]*$', message='Only alphanumeric characters are allowed.')

username = models.CharField(unique=True, max_length=20, validators=[alphanumeric])

but i still can create:

User.objects.create(username="@@")

i don't want it to create something like it...

am i doing something wrong? did i wrote a wrong regex validator?

Answer 1

I think your code should look like this:

username = models.CharField(unique=True, max_length=20, 
    validators=[
        RegexValidator(
            r'^[0-9a-zA-Z]*$', 
            message='Only alphanumericcharacters are allowed.',
            code='invalid_username'
        )
    ]
)

Answer 2

Validating performs when you call model's full_clean() method or when you use ModelForm's is_valid(). Creating new model instance in shell or in view will not raise ValidationError. More.

Answer 3

    user = CharField(
        max_length=30,
        required=True,
        validators=[
            RegexValidator(
                regex='^[a-zA-Z0-9]*$',
                message='Username must be Alphanumeric',
                code='invalid_username'
            ),
        ]

)

Source:Django regex validator message has no effect