ImportError: cannot import name 'Comment' django 1.9 - django

Question

I am new in django.
I have two app named comments and newapp.I am trying to import one of Class (Comment Class) from comments app to newapp. But I get an error called
ImportError: cannot import name 'Comment'
Here is my 'model.py' from comments app
from __future__ import unicode_literals
from django.db import models
from django.conf import settings
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
# Create your models here.
from newapp.models import NewApp
from newapp.models import Test
class CommentManager(models.Manager):
def filter_by_instance(self, instance):
content_type = ContentType.objects.get_for_model(instance.__class__)
obj_id = instance.id
qs = super(CommentManager, self).filter(content_type=content_type, object_id=obj_id)
return qs
class Comment(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, default=1)
#post = models.ForeignKey(NewApp)
content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
object_id = models.PositiveIntegerField()
content_object = GenericForeignKey('content_type', 'object_id')
content = models.TextField()
timestamp = models.DateTimeField(auto_now_add=True)
objects = CommentManager()
def __unicode__(self):
return str(self.user.username)
def __str__(self):
return str(self.user.username)
Here is the 'model.py' code for newapp app
from __future__ import unicode_literals
from django.db import models
from django.conf import settings
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.core.urlresolvers import reverse
from django.db.models.signals import pre_save
from django.utils import timezone
from django.utils.safestring import mark_safe
from django.utils.text import slugify
#here is the problem code to import below class
from comments.models import Comment
# Create your models here.
class NewApp(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, default=1)
title = models.CharField(max_length=120)
slug = models.SlugField(unique=True)
image = models.FileField(null=True, blank=True)
content = models.TextField()
updated = models.DateTimeField(auto_now=True, auto_now_add=False)
timestamp = models.DateTimeField(auto_now=False, auto_now_add=True)
def _unicode_(self):
return self.title
def _str_(self):
return self.title
def get_absolute_url(self):
return reverse("posts:detail", kwargs={"slug":self.slug})
#property
def comments(self):
instance = self
qs = Comment.objects.filter_by_instance(instance)
return qs
# #property
# def comments(self):
# instance = self
# qs = Comment.objects.filter_by_instance(instance)
# return qs
class Test(models.Model):
def _unicode_(self):
return self.title
def create_slug(instance, new_slug=None):
slug = slugify(instance.title)
if new_slug is not None:
slug = new_slug
qs = NewApp.objects.filter(slug=slug).order_by("-id")
exists = qs.exists()
if exists:
new_slug = "%s-%s" %(slug, qs.first().id)
return create_slug(instance, new_slug=new_slug)
return slug
def pre_save_post_receiver(sender, instance, *args, **kwargs):
if not instance.slug:
instance.slug = create_slug(instance)
pre_save.connect(pre_save_post_receiver, sender=NewApp)
INSTALLED APP from setting.py
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'posts',
'comments',
'newapp',
]
And finnaly i got error like this
Unhandled exception in thread started by <function check_errors.<locals>.wrapper
at 0x039B27C8>
Traceback (most recent call last):
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\utils\autoreload.py", line 226, in wrapper
fn(*args, **kwargs)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\core\management\commands\runserver.py", line 109, in inner_run
autoreload.raise_last_exception()
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\utils\autoreload.py", line 249, in raise_last_exception
six.reraise(*_exception)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\utils\six.py", line 685, in reraise
raise value.with_traceback(tb)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\utils\autoreload.py", line 226, in wrapper
fn(*args, **kwargs)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\__init__.py", line 18, in setup
apps.populate(settings.INSTALLED_APPS)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\apps\registry.py", line 108, in populate
app_config.import_models(all_models)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\apps\config.py", line 202, in import_models
self.models_module = import_module(models_module_name)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\importlib\__i
nit__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 986, in _gcd_import
File "<frozen importlib._bootstrap>", line 969, in _find_and_load
File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 662, in exec_module
File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
File "C:\Users\eXp\Desktop\venv\mysite\comments\models.py", line 8, in <module
>
from newapp.models import NewApp
File "C:\Users\eXp\Desktop\venv\mysite\newapp\models.py", line 13, in <module>
import django.comments
ImportError: No module named 'django.comments'
Unhandled exception in thread started by <function check_errors.<locals>.wrapper
at 0x034627C8>
Traceback (most recent call last):
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\utils\autoreload.py", line 226, in wrapper
fn(*args, **kwargs)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\core\management\commands\runserver.py", line 109, in inner_run
autoreload.raise_last_exception()
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\utils\autoreload.py", line 249, in raise_last_exception
six.reraise(*_exception)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\utils\six.py", line 685, in reraise
raise value.with_traceback(tb)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\utils\autoreload.py", line 226, in wrapper
fn(*args, **kwargs)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\__init__.py", line 18, in setup
apps.populate(settings.INSTALLED_APPS)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\apps\registry.py", line 108, in populate
app_config.import_models(all_models)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\site-packages
\django\apps\config.py", line 202, in import_models
self.models_module = import_module(models_module_name)
File "C:\Users\eXp\AppData\Local\Programs\Python\Python35-32\lib\importlib\__i
nit__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 986, in _gcd_import
File "<frozen importlib._bootstrap>", line 969, in _find_and_load
File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 662, in exec_module
File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
File "C:\Users\eXp\Desktop\venv\mysite\comments\models.py", line 8, in <module
>
from newapp.models import NewApp
File "C:\Users\eXp\Desktop\venv\mysite\newapp\models.py", line 14, in <module>
from comments.models import Comment
ImportError: cannot import name 'Comment'

Answer 1

You're importing newapp from comments and comments from newapp. In python, you can't have circular imports like this. Quick fix: remove the import from newapp inside comments's models.py and replace with a name reference, like this:
class Comment(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, default=1)
post = models.ForeignKey('newapp.NewApp') # <= HERE
content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
object_id = models.PositiveIntegerField()
content_object = GenericForeignKey('content_type', 'object_id')
content = models.TextField()
timestamp = models.DateTimeField(auto_now_add=True)
objects = CommentManager()