Error when migrating the DB

[memaldi]

Django launches the following error when executing python manage.py migrate:

  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 367, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 359, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 294, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 342, in execute
    self.check()
  File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 374, in check
    include_deployment_checks=include_deployment_checks,
  File "/usr/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 62, in _run_checks
    issues.extend(super(Command, self)._run_checks(**kwargs))
  File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 361, in _run_checks
    return checks.run_checks(**kwargs)
  File "/usr/local/lib/python2.7/site-packages/django/core/checks/registry.py", line 81, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/usr/local/lib/python2.7/site-packages/django/core/checks/urls.py", line 14, in check_url_config
    return check_resolver(resolver)
  File "/usr/local/lib/python2.7/site-packages/django/core/checks/urls.py", line 24, in check_resolver
    for pattern in resolver.url_patterns:
  File "/usr/local/lib/python2.7/site-packages/django/utils/functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/usr/local/lib/python2.7/site-packages/django/urls/resolvers.py", line 313, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/usr/local/lib/python2.7/site-packages/django/utils/functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/usr/local/lib/python2.7/site-packages/django/urls/resolvers.py", line 306, in urlconf_module
    return import_module(self.urlconf_name)
  File "/usr/local/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "/src/labman_ud/urls.py", line 31, in <module>
    url(r'^publications/', include('entities.publications.urls')),
  File "/usr/local/lib/python2.7/site-packages/django/conf/urls/__init__.py", line 50, in include
    urlconf_module = import_module(urlconf_module)
  File "/usr/local/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "/src/entities/publications/urls.py", line 7, in <module>
    from entities.publications.views import LatestPublicationsFeed
  File "/src/entities/publications/views.py", line 14, in <module>
    from .forms import PublicationSearchForm
  File "/src/entities/publications/forms.py", line 31, in <module>
    class PublicationSearchForm(forms.Form):
  File "/src/entities/publications/forms.py", line 55, in PublicationSearchForm
    for choice in types:
  File "/usr/local/lib/python2.7/site-packages/django/db/models/query.py", line 256, in __iter__
    self._fetch_all()
  File "/usr/local/lib/python2.7/site-packages/django/db/models/query.py", line 1087, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/usr/local/lib/python2.7/site-packages/django/db/models/query.py", line 155, in __iter__
    for row in compiler.results_iter():
  File "/usr/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 789, in results_iter
    results = self.execute_sql(MULTI)
  File "/usr/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 835, in execute_sql
    cursor.execute(sql, params)
  File "/usr/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/usr/local/lib/python2.7/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/usr/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: relation "publications_publication" does not exist
LINE 1: ...INCT "publications_publication"."child_type" FROM "publicati...

I think that the error is that chained imports starting from urls.py reach labman_ud/entities/publications/forms.py file, and this file has the following code in its "initialization":

PUBLICATION_TYPES = (())
types = Publication.objects.all().values_list('child_type', flat=True).order_by('child_type').distinct()
for choice in types:
    PUBLICATION_TYPES = PUBLICATION_TYPES + ((choice, choice),)

Django tries to load types but the database is not still created.