I have two models Company and Actions:
from companies.models import Company
class Action(models.Model):
company = models.ForeignKey(Company, blank=True, null=True, related_name='activity', on_delete=models.CASCADE)
I have then an utility in utils.py
from .models import Action
def create_action(user, verb, target_name=None, target=None):
action = Action(user=user, verb=verb, target=target)
This utility I called in Company model on def save, so on Company Model I have:
from not.utils import create_action
so Action Model import Company Model as FK, utils import Action Model, and Company Model import utils
Now, because of circular import Django gives an error:
ImportError: cannot import name 'Company'
I saw some q/a here to use import directly (without from) I tried but didn't worked
import not.utils as nt
nt.create_action(...)
Remove the Company import from actions/models.py and use a string instead:
class Action(models.Model):
company = models.ForeignKey('companies.Company', blank=True, null=True, related_name='activity', on_delete=models.CASCADE)
Related
I somehow can not import my models from another app. I already looked it up and tried but does not work.
events/models.py
class Registration(models.Model):
category = models.ForeignKey(Category, on_delete=models.CASCADE)
user = models.ForeignKey(User, on_delete=models.CASCADE)
team = models.CharField(max_length=50, blank=True)
date_created = models.DateTimeField(auto_now_add=True)
def save(self, *args, **kwargs):
payment = Payment.objects.create(registration=self)
super().save(*args, **kwargs)
When I run python manage.py makemigrations I get this.
Error
File "C:\Users\Rubber\ems\events\models.py", line 5, in <module>
from payments.models import Payment
File "C:\Users\Rubber\ems\payments\models.py", line 6, in <module>
from events.models import Registration
ImportError: cannot import name 'Registration'
payments/models.py
import uuid
from django.db import models
from django.utils import timezone
from events.models import Registration # THIS WONT WORK
def _create_uuid():
return uuid.uuid1()
def _get_uuid():
return _create_uuid()
class Payment(models.Model):
uuid = models.CharField(max_length=1, default=_get_uuid)
paid = models.BooleanField(default=False)
registration = models.ForeignKey(Registration, on_delete=models.CASCADE)
What am I doing wrong?
You have a circular import. In this case, you can avoid it by removing the Registration import and using the string instead:
class Payment(models.Model):
registration = models.ForeignKey('events.Registration', on_delete=models.CASCADE)
Another option would be to move the Payment.objects.create() code into a signal. Note that your current save() method creates a Payment every time the registration is saved, which might not be what you want.
I have these models below
# user profile models file
from ad.models import FavoriteAd
class UserProfile(models.Model):
def get_user_favorite_ad(self):
return FavoriteAd.objects.filter(fav_user=self)
# ad models file
from user_profile.models import UserProfile
class FavoriteAd(models.Model):
fav_user = models.ForeignKey(UserProfile, blank=False, on_delete=models.CASCADE)
I have tried using these but it give me the NameError UserProfile not found
# ad models files
class FavoriteAd(models.Model):
fav_user = models.ForeignKey('user_profile.UserProfile', blank=False, on_delete=models.CASCADE)
Also tried these as well still got error that model are not ready
# ad models files
from django.apps import apps
UserProfile = apps.get_model('user_profile', 'UserProfile')
class FavoriteAd(models.Model):
fav_user = models.ForeignKey(UserProfile, blank=False, on_delete=models.CASCADE)
You are using FavoriteAd inside get_user_favorite_ad method of
UserProfile model
Thats the reason you are unable to import it in FavoriteAd and this is causing circular import.
For fetching favorite ads of that user, Use favoritead_set to get related objects
# remove that import as well
# from ad.models import FavoriteAd
class UserProfile(models.Model):
def get_user_favorite_ad(self):
return self.favoritead_set.all()
Problem
I have 2 models, leads and notes. I want a lead to be able to have 1 or more notes. I have used a generic foreign key because I want to plan for the future and a note could be assigned to say a person or a meeting for example.
Following the instructions for django rest framework and Rest Framework Generic Relations I am trying to import one serializer from the other to make a reverse relation possible.
Error
I can't import the serializers in both files(call one serializer from the other) because I get:
File "/Users/james/Documents/UtilityCRM-Server/crm/leads/urls.py", line 2, in <module>
from leads import views
File "/Users/james/Documents/UtilityCRM-Server/crm/leads/views.py", line 11, in <module>
from leads.serializers import LeadSerializer
File "/Users/james/Documents/UtilityCRM-Server/crm/leads/serializers.py", line 4, in <module>
from notes.serializers import NoteSerializer
File "/Users/james/Documents/UtilityCRM-Server/crm/notes/serializers.py", line 6, in <module>
from leads.serializers import LeadSerializer
ImportError: cannot import name LeadSerializer
Its weird because if I open the django shell and run the following it lets me import them all:
from leads.serializers import LeadSerializer
from notes.serializers import NotesSerializer
from callbacks.serializers import CallbackSerializer
Any help would be greatly appreciated!
Code
This is my installed app section of my settings file:
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
# 3rd Party Apps
'rest_framework',
'generic_relations',
# My Apps
'leads.apps.LeadsConfig',
'callbacks.apps.CallbacksConfig',
'notes.apps.NotesConfig',
]
notes/models.py
from __future__ import unicode_literals
from django.db import models
from django.utils import timezone
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
class Note(models.Model):
author = models.ForeignKey('auth.User')
title = models.CharField(max_length=100)
text = models.TextField()
created_date = models.DateTimeField(default=timezone.now)
# Relations
content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
object_id = models.PositiveIntegerField()
note_object = GenericForeignKey('content_type', 'object_id')
def __str__(self):
return self.title
leads/models.py
from __future__ import unicode_literals
from django.db import models
from django.contrib.contenttypes.fields import GenericRelation
from django.utils import timezone
from notes.models import Note
from callbacks.models import Callback
GAS = 'G'
ELECTRICITY = 'E'
LEAD_TYPE_CHOICES = (
(GAS, 'Gas'),
(ELECTRICITY, 'Electricity'),
)
# Create your models here.
class Lead(models.Model):
author = models.ForeignKey('auth.User')
type = models.CharField(
max_length=1,
choices=LEAD_TYPE_CHOICES,
default=GAS,
)
business_registration_number = models.IntegerField(max_length=20)
business_name = models.CharField(max_length=50)
mpan = models.IntegerField(max_length=21)
supplier = models.CharField(max_length=45)
contract_length = models.IntegerField(max_length=2)
contract_start_date = models.DateField()
contract_end_date = models.DateField()
address_line_1 = models.CharField(max_length=45)
address_line_2 = models.CharField(max_length=45)
address_line_3 = models.CharField(max_length=45)
address_city = models.CharField(max_length=45)
address_county = models.CharField(max_length=45)
address_postcode = models.CharField(max_length=10)
contact_title = models.CharField(max_length=45)
contact_first_name = models.CharField(max_length=45)
contact_middle_name = models.CharField(max_length=45)
contact_last_name = models.CharField(max_length=45)
contact_telephone = models.IntegerField(max_length=11)
contact_email = models.EmailField(max_length=60)
created_date = models.DateTimeField(default=timezone.now)
# Relations
assigned_to = models.ForeignKey('auth.User', related_name='+')
#from_batch = models.ForeignKey('data_batch.DataBatch', related_name='+')
#callbacks = GenericRelation(Callback)
notes = GenericRelation(Note)
class Meta:
ordering = ('contract_end_date', 'business_name',)
def __str__(self):
return self.business_name
I have 2 serializers:
leads/serializers.py
from rest_framework import serializers
from leads.models import Lead, LEAD_TYPE_CHOICES
from notes.serializers import NoteSerializer
class LeadSerializer(serializers.ModelSerializer):
notes = NoteSerializer(many=True, read_only=True)
class Meta:
model = Lead
fields = (
'id',
'business_name',
'business_registration_number',
'supplier',
'contract_length',
'contract_start_date',
'notes'
)
notes/serializers.py
from generic_relations.relations import GenericRelatedField
from rest_framework import serializers
from notes.models import Note
from leads.models import Lead
from leads.serializers import LeadSerializer
from callbacks.models import Callback
from callbacks.serializers import CallbackSerializer
class NoteSerializer(serializers.ModelSerializer):
"""
A `Note` serializer with a `GenericRelatedField` mapping all possible
models to their respective serializers.
"""
note_object = GenericRelatedField({
Lead: LeadSerializer(),
Callback: CallbackSerializer()
})
class Meta:
model = Note
fields = (
'id',
'author',
'title',
'text',
'created_date',
'note_object',
)
As I have mentioned previously in a comment, I believe this happens due to circular (cyclic) imports in Python.
This happens particularly when you are declaring related fields in models, and some models have not been instanced yet.
In this case, when you execute your program, it tries to import LeadSerializer, that requires importing NoteSerializer, that requires importing LeadSerializer, that requires importing NoteSerializer... see where this is going?
Your stacktrace says it all:
from leads.serializers import LeadSerializer
from notes.serializers import NoteSerializer
from leads.serializers import LeadSerializer
Generating ImportError: cannot import name LeadSerializer
What I have done to solve this was declaring all the serializers in a single file. Therefore, you have two options:
Move LeadSerializer to notes/serializers.py
Move NoteSerializer to leads/serializers.py
It is not the most elegant way to solve this, but it has done its trick.
The section below provides no further explanation on how to solve this problem, but an observation regarding this issue.
Perhaps Django & DRF could futurely provide methods to avoid this, such as declaring the serializers as
note_object = GenericRelatedField({
Lead: 'leads.serializers'.LeadSerializer,
Callback: CallbackSerializer()
})
or
notes = 'notes.serializers'.NoteSerializer(many=True, read_only=True)
Faced with this and made this thing:
notes = serializers.SerializerMethodField()
def get_notes(self, obj):
from leads.serializers import LeadSerializer
return LeadSerializer(<your_queryset>, many=True/False, read_only=True/False).data
There is an idea to tackle this before I have also got this same error here I will explain to you how I resolve this.
Put your apps inside the project directory
project
-project
-appname1
-models.py
-serilizer.py
-appname2
-models.py
-serilizer.py
-settings.py
in settings.py
INSTALLED_APPS = ['project.appname1', 'project.appname2']
then try to import appname1 serializers into appname2
like this
from project.appname1.serializers import( ArtistSerializer, ArtisTokenSerilizer, ProfessionSerilizer, FollowersSerializer,
FollowingSerializer, ChatMessageSerializer, SendMessageSerializer, ConversationMessageSerializer,
ProjectTypeSerializer)
I've just followed the tutorial to install GeoDjango for Django 1.9 and I'm trying to write my user models, but I'm not sure which tables should inherit from django.contrib.gis.db.models rather than the regular django.db.models.
I'm making a Customer table which has a PointField for their location, and a table that inherits from customer named Traveller. I also have a third table Equipment which has a foreign key to Traveller.
Is my inheritance right? Is there a better way to do it?
from django.contrib.gis.db import models as gis_models
from django.db import models
class Customer(gis_models.Model):
user = gis_models.OneToOneField(
settings.AUTH_USER_MODEL,
on_delete=models.SET_NULL,
blank=True,
null=True
)
location = gis_models.CharField(max_length=100)
gis_location = gis_models.PointField(u"longitude/latitude",
geography=True, blank=True, null=True)
name = gis_models.CharField(max_length=100)
class Meta:
abstract = True
class Traveller(Customer):
will_travel = gis_models.NullBooleanField()
class Equipment(models.Model):
name = models.CharField(max_length=50)
description = models.CharField(max_length=100)
owner = models.ForeignKey(
'Traveller',
on_delete=models.SET_NULL,
null=True
)
Thanks
This is the code from django/contrib/gis/db/models/__init__.py
from django.db.models import * # NOQA isort:skip
from django.contrib.gis.db.models.aggregates import * # NOQA
from django.contrib.gis.db.models.fields import ( # NOQA
GeometryCollectionField, GeometryField, LineStringField,
MultiLineStringField, MultiPointField, MultiPolygonField, PointField,
PolygonField, RasterField,
)
from django.contrib.gis.db.models.manager import GeoManager # NOQA
gis module imports all models defined in django, and adds some of its own.
So you can safely inherit all your models from the gis models. It's the same thing.
I understand how to break up models, and I understand why circular module dependencies blow things up, but I've run across a problem where breaking up a model into separate files appears to be causing circular dependencies. Here's an exerpt from the code, and I'll follow it up with the traceback from the failing process:
elearning/tasks.py
from celery.task import task
#task
def decompress(pk):
from elearning.models import Elearning
Elearning.objects.get(pk=pk).decompress()
elearning/models.py
from competency.models import CompetencyProduct
from core.helpers import ugc_elearning
from elearning.fields import ArchiveFileField
class Elearning(CompetencyProduct):
archive = ArchiveFileField(upload_to=ugc_elearning)
def decompress(self):
import zipfile
src = self.archive.path
dst = src.replace(".zip","")
print "Decompressing %s to %s" % (src, dst)
zipfile.ZipFile(src).extractall(dst)
ecom/models/products.py
from django.db import models
from django.utils.translation import ugettext_lazy as _
from core.models import Slugable, Unique
from django_factory.models import Factory
from core.helpers import ugc_photos
class Product(Slugable, Unique, Factory):
photo = models.ImageField(upload_to=ugc_photos, width_field="photo_width", height_field="photo_height", blank=True)
photo_width = models.PositiveIntegerField(blank=True, null=True, default=0)
photo_height = models.PositiveIntegerField(blank=True, null=True, default=0)
description = models.TextField()
price = models.DecimalField(max_digits=16, decimal_places=2)
created = models.DateTimeField(auto_now_add=True)
modified = models.DateTimeField(auto_now=True)
ecom/models/__init__.py
from django.contrib.auth.models import User
from django.db import models
from ecom.models.products import Product, Credit, Subscription
from ecom.models.permissions import Permission
from ecom.models.transactions import Transaction, DebitTransaction, CreditTransaction, AwardTransaction, FinancialTransaction, PermissionTransaction, BundleTransaction
competency/models.py
from django.db import models
from django.utils.translation import ugettext_lazy as _
from core.models import Slugable, Unique
from ecom.models import Product
from rating.models import Rated
from trainer.models import Trainer
class Competency(Slugable, Unique):
class Meta:
verbose_name = _("Competency")
verbose_name_plural = _("Competencies")
description = models.TextField()
class CompetencyProduct(Product, Rated):
class Meta:
verbose_name = _("Product")
verbose_name_plural = _("Products")
release = models.DateField(auto_now_add=True)
trainers = models.ManyToManyField(Trainer)
competencies = models.ManyToManyField(Competency, related_name="provided_by")
requirements = models.ManyToManyField(Competency, related_name="required_for", blank=True, null=True)
forsale = models.BooleanField("For Sale", default=True)
ecom/models/permissions.py
from django.contrib.auth.models import User
from django.db import models
from django.utils.translation import ugettext_lazy as _
from treebeard.mp_tree import MP_Node
from collective.models import Collective
from course.models import Course
from ecom.models.products import Product
class Permission(MP_Node):
class Meta:
app_label = "ecom"
product = models.ForeignKey(Product, related_name="permissions")
user = models.ForeignKey(User, related_name="permissions")
collective = models.ForeignKey(Collective, null=True)
course = models.ForeignKey(Course, null=True)
redistribute = models.BooleanField(default=False)
created = models.DateTimeField(auto_now_add=True)
modified = models.DateTimeField(auto_now=True)
accessed = models.DateTimeField(auto_now=True)
course/models.py
from django.db import models
from django.utils.translation import ugettext_lazy as _
from competency.models import CompetencyProduct
from ecom.models import Product
from rating.models import Rated
class Chapter(models.Model):
seq = models.PositiveIntegerField(name="Sequence", help_text="Chapter number")
name = models.CharField(max_length=128)
note = models.CharField(max_length=128)
class Course(Product, Rated):
level = models.PositiveIntegerField(choices=CompetencyProduct.LEVELS)
chapters = models.ManyToManyField(Chapter)
class Bundle(models.Model):
class Meta:
unique_together = (("product", "chapter"),)
product = models.ForeignKey(Product, related_name="bundles")
chapter = models.ForeignKey(Chapter, related_name="bundles")
amount = models.PositiveIntegerField()
seq = models.PositiveIntegerField(name="Sequence", default=1)
From what I can see, there's no explicit circular recursion here, save for the required references in __init__.py which appears to be where things are blowing up in my code. Here's the traceback:
File "/path/to/project/virtualenv/lib/python2.6/site-packages/celery/execute/trace.py", line 47, in trace
return cls(states.SUCCESS, retval=fun(*args, **kwargs))
File "/path/to/project/virtualenv/lib/python2.6/site-packages/celery/app/task/__init__.py", line 247, in __call__
return self.run(*args, **kwargs)
File "/path/to/project/virtualenv/lib/python2.6/site-packages/celery/app/__init__.py", line 175, in run
return fun(*args, **kwargs)
File "/path/to/project/django/myproj/elearning/tasks.py", line 5, in decompress
from elearning.models import Elearning
File "/path/to/project/django/myproj/elearning/models.py", line 2, in <module>
from competency.models import CompetencyProduct
File "/path/to/project/django/myproj/competency/models.py", line 5, in <module>
from ecom.models import Product
File "/path/to/project/django/myproj/ecom/models/__init__.py", line 5, in <module>
from ecom.models.permissions import Permission
File "/path/to/project/django/myproj/ecom/models/permissions.py", line 8, in <module>
from course.models import Course
File "/path/to/project/django/myproj/course/models.py", line 4, in <module>
from competency.models import CompetencyProduct
ImportError: cannot import name CompetencyProduct
All I'm trying to do here is import that Elearning model, which is a subclass of CompetencyProduct, and in turn, Product. However, because Product comes from a break-up of the larger ecom/models.py, the ecom/__init__.py file contains the obligatory import of all of the broken-out models, including Permission which has to import Course which requires CompetencyProduct.
The wacky thing is that the whole site works pefectly. Logins, purchases, everything. This problem only occurs when I'm trying to run celery in the background and a new task is loaded or I try to run a shell script using the Django environment.
Is my only option here to remove Permission from the ecom app, or there a better, smarter way to handle this? Additionally, any comments on how I've laid out the project in general are appreciated.
Your problem is that Permission imports Product, but both are imported in ecom/models/__init__.py. You should find a way to either have these two models in the same file or separate them into two apps.