pytest execute code before database created - django

Question

In AdminForm I prevent the user from duplicating the records.
from django import forms
from django.contrib.auth.models import User
from apps.accounting_users.models import AccountingUser
from apps.marketing_users.models import MarketingUser
from apps.mgmt_users.models import ManagementUser
from apps.serv_mgrs_users.models import ServiceMgmtUser
from apps.serv_staff_users.models import ServiceStaffUser
class BaseDjangoAdminRoleForm(forms.ModelForm):
user = forms.ModelChoiceField(
queryset=User.objects.exclude(
username__in=[record.user.username for record in AccountingUser.objects.all()] +
[record.user.username for record in MarketingUser.objects.all()] +
[record.user.username for record in ManagementUser.objects.all()] +
[record.user.username for record in ServiceMgmtUser.objects.all()] +
[record.user.username for record in ServiceStaffUser.objects.all()],
)
)
mgmt_users/models.py
from apps.commons.models import AbstractSBrandUser
class ManagementUser(AbstractSBrandUser):
pass
commons/models
class AbstractSBrandUser(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
branch = models.ForeignKey(Branch, on_delete=models.SET_NULL, null=True)
mobile = models.CharField(max_length=15)
class Meta:
abstract = True
OSX 10.12.4 pytest is normal
Debian:Jessie is broken
File "/usr/local/lib/python3.6/site-packages/django/contrib/admin/apps.py", line 23, in ready
self.module.autodiscover()
File "/usr/local/lib/python3.6/site-packages/django/contrib/admin/__init__.py", line 26, in autodiscover
autodiscover_modules('admin', register_to=site)
File "/usr/local/lib/python3.6/site-packages/django/utils/module_loading.py", line 50, in autodiscover_modules
import_module('%s.%s' % (app_config.name, module_to_search))
File "/usr/local/lib/python3.6/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 978, in _gcd_import
File "<frozen importlib._bootstrap>", line 961, in _find_and_load
File "<frozen importlib._bootstrap>", line 950, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 205, in _call_with_frames_removed
File "/buddy/siam-sbrand/portal/apps/mgmt_users/admin.py", line 3, in <module>
from apps.commons.forms import BaseDjangoAdminRoleForm
File "/buddy/siam-sbrand/portal/apps/commons/forms.py", line 11, in <module>
class BaseDjangoAdminRoleForm(forms.ModelForm):
File "/buddy/siam-sbrand/portal/apps/commons/forms.py", line 17, in BaseDjangoAdminRoleForm
[record.user.username for record in ServiceMgmtUser.objects.all()] +
File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 256, in __iter__
self._fetch_all()
File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 1087, in _fetch_all
Question:
I had checked the syntax based on python3 already.
And I had checked the filter syntax of Django1.10 already.
python manage.py shell run fine. No error at all.
How can I use queryset in the AdminForm of the Django and pass the test?
Do I need to sacrify testing for this feature?

Answer 1

You can't use querysets like [record.user.username for record in AccountingUser.objects.all()] in your model form definition. Django tries to evaluate the queryset when the module is loaded. If the table has not been created yet, this will give an error.
You can fix the problem by setting the queryset in the __init__ method.
class BaseDjangoAdminRoleForm(forms.ModelForm):
user = forms.ModelChoiceField(queryset=User.objects.none())
def __init__(self, *args, **kwargs):
super(BaseDjangoAdminRoleForm, self).__init__(*args, **kwargs)
self.fields['user'].queryset = User.objects.exclude(...)
This has the advantage of evaluating the usernames every time the form is created - at the moment, they are only evaluated once when the server starts.