Django Models - Circular-import-issue

My Django-Project uses Three Apps, chat, user, sowi. Every App having models structured in the following way. I'm getting an error when starting the Server, i think it is because i

Solution 1:

It is better to refer to models with string literals, than to refer to it with references to the model class. Django can handle this and will automatically resolve these:

# chat/models.pyfrom django.db import models

classChat(models.Model):
    name = models.CharField(max_length=100, default="private")

classMessage(models.Model):
    sender = models.ForeignKey('user.User', on_delete=models.CASCADE)
    receiver = models.ForeignKey(Chat, on_delete=models.CASCADE)

# user/models.pyfrom django.db import models

classUser(AbstractUser):
    chats = models.ManyToManyField(Chat, blank=True)
    subscriptions = models.ManyToManyField('sowi.Sowi', related_name="subscriptions", blank=True)
    memberships = models.ManyToManyField('sowi.Sowi', related_name="memberships", blank=True)
    blocked = models.ManyToManyField("self", related_name="blocked", blank=True)

# sowi/models.pyfrom django.db import models

classSowi(models.Model):
    owner = models.ForeignKey('user.User', on_delete=models.CASCADE)
    chat = models.OneToOneField('chat.Chat', blank=True, null=True, on_delete=models.CASCADE)

It is even better when you reference the user model [Django-doc] to set the AUTH_USER_MODEL setting [Django-doc], and use this setting, such that if you later change your mind, you can more conveniently change this:

# chat/models.pyfrom django.conf import settings
from django.db import models

classChat(models.Model):
    name = models.CharField(max_length=100, default="private")

classMessage(models.Model):
    sender = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    receiver = models.ForeignKey(Chat, on_delete=models.CASCADE)

# user/models.pyfrom django.db import models

classUser(AbstractUser):
    chats = models.ManyToManyField(Chat, blank=True)
    subscriptions = models.ManyToManyField('sowi.Sowi', related_name="subscriptions", blank=True)
    memberships = models.ManyToManyField('sowi.Sowi', related_name="memberships", blank=True)
    blocked = models.ManyToManyField("self", related_name="blocked", blank=True)

# sowi/models.pyfrom django.conf import settings
from django.db import models

classSowi(models.Model):
    owner = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    chat = models.OneToOneField('chat.Chat'

Solution 2:

try:

classUser(AbstractUser):
    chats = models.ManyToManyField('chat.Chat', blank=True)
    subscriptions = models.ManyToManyField('sowi.Sowi', related_name="subscriptions", blank=True)
    memberships = models.ManyToManyField('sowi.Sowi', related_name="memberships", blank=True)
    blocked = models.ManyToManyField("self", related_name="blocked", blank=True)

The problem with your code is that you're importing Chat and Sowi in user models.py, and then you're trying to import user models in Chat and Sowi. You see the Circular Import there?