django-factory_boy AttributeError：“ NoneType”对象没有属性“ _meta”

Question

I'm writing unit tests for my Django REST Framework app and I'm creating my fake testing data using factory_boy . I've come across the following error message when I try to run my tests

File "/Users/thomasheatwole/osf-meetings/meetings/conferences/tests.py", line 69, in setUp
  contributor = UserFactory()
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/factory/base.py", line 67, in __call__
  return cls.create(**kwargs)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/factory/base.py", line 594, in create
  return cls._generate(True, attrs)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/factory/base.py", line 519, in _generate
  obj = cls._prepare(create, **attrs)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/factory/base.py", line 494, in _prepare
  return cls._create(model_class, *args, **kwargs)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/factory/django.py", line 181, in _create
  return manager.create(*args, **kwargs)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/db/models/manager.py", line 122, in manager_method
  return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/db/models/query.py", line 401, in create
  obj.save(force_insert=True, using=self.db)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/db/models/base.py", line 708, in save
  force_update=force_update, update_fields=update_fields)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/db/models/base.py", line 745, in save_base
  update_fields=update_fields, raw=raw, using=using)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/dispatch/dispatcher.py", line 192, in send
  response = receiver(signal=self, sender=sender, **named)
File "/Users/thomasheatwole/osf-meetings/meetings/submissions/signals.py", line 19, in add_permissions_on_submission_save
  submission, submission_contributor, conference_admin, approval)
File "/Users/thomasheatwole/osf-meetings/meetings/submissions/permissions.py", line 167, in set_unapproved_submission_permissions
  approval, submission_contributor)
File "/Users/thomasheatwole/osf-meetings/meetings/approvals/permissions.py", line 62, in add_approval_permissions_to_submission_contributor
  assign_perm("approvals.delete_approval", submission_contributor, approval)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/guardian/shortcuts.py", line 92, in assign_perm
  return model.objects.assign_perm(perm, user, obj)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/guardian/managers.py", line 43, in assign_perm
  obj_perm, created = self.get_or_create(**kwargs)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/db/models/manager.py", line 122, in manager_method
  return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/db/models/query.py", line 467, in get_or_create
  return self._create_object_from_params(lookup, params)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/db/models/query.py", line 499, in _create_object_from_params
  obj = self.create(**params)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/db/models/query.py", line 401, in create
  obj.save(force_insert=True, using=self.db)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/guardian/models.py", line 39, in save
  content_type = ContentType.objects.get_for_model(self.content_object)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/contrib/contenttypes/models.py", line 55, in get_for_model
  opts = self._get_opts(model, for_concrete_model)
File "/Users/thomasheatwole/.virtualenvs/django/lib/python2.7/site-packages/django/contrib/contenttypes/models.py", line 32, in _get_opts
  model = model._meta.concrete_model
AttributeError: 'NoneType' object has no attribute '_meta'

I pretty much have no clue what's going on since my understanding of backend structure isn't great. Here's the factories:

class UserFactory(factory.DjangoModelFactory):
    class Meta: 
        model = User

class ConferenceFactory(factory.DjangoModelFactory):
    class Meta:
        model = Conference


class ApprovalFactory(factory.DjangoModelFactory):
    class Meta:
        model = approvalModels.Approval


class SubmissionFactory(factory.DjangoModelFactory):
    class Meta:
        model = submissionModels.Submission

And here's where I call them:

def setUp(self):
    self.user1 = UserFactory(
        username = 'Leo',
        id = '99'
        )
    self.user2 = UserFactory(
        username = 'LeoLeo'
        )
    self.conference = ConferenceFactory(
        admin = self.user1
    )
    self.submission1 = SubmissionFactory(
        conference = self.conference,
        contributor = UserFactory()
        )
    self.submission2 = SubmissionFactory(
        conference = self.conference,
        contributor = UserFactory()
        )

If you look through the error message, it's specifically complaining about contributor = UserFactory()

Let me know if there's an easy fix, or even some explanation of what's going on would be nice.

Thanks so much!

Here's the file:

tests.py

Answer 1

You need to add correct relations ( SubFactory ) in the factory definition first.

Please read this part carefully:

http://factoryboy.readthedocs.io/en/latest/recipes.html#copying-fields-to-a-subfactory