Migration errors from SQLite to Postgres

[Song Yang]

To put my app on Heroku, I am changing my database from SQLite to Postgres at the end of my project. Everything works fine locally on SQLite. But during python manage.py migrate --run-syncdb, I get a ProgrammingError. I was planning on loading the dumped json later in Postgres.

I created a branch on my repo for you to reproduce this bug. The branch is postgres and the commit is ​https://github.com/XsongyangX/uml-fragment-labeling/commit/c14a49990b115bd0b8ba74640a7c65da301562d3

Here is the log.

$ py manage.py migrate --run-syncdb
Traceback (most recent call last):
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\ba
ckends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
psycopg2.errors.UndefinedTable: relation "labeling_model" does not exist
LINE 1: ...del"."classes", "labeling_model"."relations" FROM "labeling_...
                                                             ^


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\Song\Documents\UDEM\master thesis\uml data\database\umllabels\m
anage.py", line 22, in <module>
    main()
  File "C:\Users\Song\Documents\UDEM\master thesis\uml data\database\umllabels\m
anage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
management\__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
management\__init__.py", line 413, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
management\base.py", line 354, in run_from_argv
    self.execute(*args, **cmd_options)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
management\base.py", line 398, in execute
    output = self.handle(*args, **options)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
management\base.py", line 89, in wrapped
    res = handle_func(*args, **kwargs)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
management\commands\migrate.py", line 75, in handle
    self.check(databases=[database])
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
management\base.py", line 419, in check
    all_issues = checks.run_checks(
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
checks\registry.py", line 76, in run_checks
    new_errors = check(app_configs=app_configs, databases=databases)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
checks\urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\core\
checks\urls.py", line 23, in check_resolver
    return check_method()
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\urls\
resolvers.py", line 412, in check
    for pattern in self.url_patterns:
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\utils
\functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\urls\
resolvers.py", line 598, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\utils
\functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\urls\
resolvers.py", line 591, in urlconf_module
    return import_module(self.urlconf_name)
  File "C:\Program Files\Python39\lib\importlib\__init__.py", line 127, in impor
t_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 790, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "C:\Users\Song\Documents\UDEM\master thesis\uml data\database\umllabels\u
mllabels\urls.py", line 24, in <module>
    path('labeling/', include(('labeling.urls', 'labeling'), namespace="labeling
")),
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\urls\
conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "C:\Program Files\Python39\lib\importlib\__init__.py", line 127, in impor
t_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 790, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "C:\Users\Song\Documents\UDEM\master thesis\uml data\database\umllabels\l
abeling\urls.py", line 3, in <module>
    from . import views
  File "C:\Users\Song\Documents\UDEM\master thesis\uml data\database\umllabels\l
abeling\views.py", line 2, in <module>
    from labeling.sampler import Sampler, block
  File "C:\Users\Song\Documents\UDEM\master thesis\uml data\database\umllabels\l
abeling\sampler.py", line 108, in <module>
    class Sampler:
  File "C:\Users\Song\Documents\UDEM\master thesis\uml data\database\umllabels\l
abeling\sampler.py", line 111, in Sampler
    largest_class_count = Model.objects.order_by("-classes").first().classes
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\mo
dels\query.py", line 674, in first
    for obj in (self if self.ordered else self.order_by('pk'))[:1]:
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\mo
dels\query.py", line 280, in __iter__
    self._fetch_all()
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\mo
dels\query.py", line 1324, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\mo
dels\query.py", line 51, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=
self.chunk_size)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\mo
dels\sql\compiler.py", line 1175, in execute_sql
    cursor.execute(sql, params)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\ba
ckends\utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._e
xecute)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\ba
ckends\utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\ba
ckends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\ut
ils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\Song\AppData\Roaming\Python\Python39\site-packages\django\db\ba
ckends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: relation "labeling_model" does not exist
LINE 1: ...del"."classes", "labeling_model"."relations" FROM "labeling_...

[Tim Graham]

This isn't a bug. You have ​a query running at the module level which isn't safe. See ​django-developers discussion for more details.

Next time, please use TicketClosingReasons/UseSupportChannels to debug your issue and open an issue here only if you confirm that Django is at fault. Thanks!