Why is there a circular dependency of django imports?

Question

Django

I am getting an error:

cannot import name 'Device' from partially initialized module 'cms.models' (most likely due to a circular import)

I found out that it is related to the circular import of validators:

from django.core.validators import MaxValueValidator, MinValueValidator
from .validators import UniversalMaxValidator, UniversalMinValidator

An example of using these validators in a model:

height = models.FloatField(validators=[UniversalMinValidator(metric_min=50, inch_min=1.8).validate(), UniversalMaxValidator(metric_max=260, inch_max=8.7).validate()], verbose_name=_('height'),
                               help_text=None, default=0, error_messages={'required': _('Indicate your height')})
    weight = models.FloatField(validators=[MinValueValidator(20), MaxValueValidator(1330)], verbose_name=_('weight'),
                               help_text=None, default=0, error_messages={'required': _('Enter your weight')})

validators.py (from which I import custom validators):

from django.core.exceptions import ValidationError
from django.core.validators import MaxValueValidator, MinValueValidator, BaseValidator
from django.utils.translation import gettext_lazy as _

from .views import HealthData


class UniversalMinValidator(BaseValidator):
    def __init__(self, metric_min, inch_min):
        self.metric_min = metric_min
        self.inch_min = inch_min
        self.measuring_system = self.request.user.health_data.measuring_system

    def validate(self):
        if self.measuring_system == 'Metric':
            return MinValueValidator(self.metric_min)
        else:
            return MinValueValidator(self.inch_min)


class UniversalMaxValidator(BaseValidator):
    def __init__(self, metric_max, inch_max):
        self.metric_min = metric_max
        self.inch_min = inch_max
        self.measuring_system = self.request.user.health_data.measuring_system

    def validate(self):
        if self.measuring_system == 'Metric':
            return MinValueValidator(self.metric_max)
        else:
            return MinValueValidator(self.inch_max)

When I remove the import of the custom validator, everything works, but I need to use it so that the validator is converted depending on the selected calculus

Answer 1

Remove line 5 from validators.py. It turns out that you are importing validators into views, and views into validators, although the purpose of this import is not clear.