Django 2.2 - django.db.utils.OperationalError: 沒有這樣的表

Question

我正在拔頭發。 我只是無法讓遷移工作了。 每次運行python3 manage.py makemigrations或python3 manage.py makemigrations app_name ，都會出現以下錯誤：

    Traceback (most recent call last):
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 383, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: no such table: catalog_fault

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

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/management/base.py", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/management/base.py", line 361, in execute
    self.check()
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/management/base.py", line 390, in check
    include_deployment_checks=include_deployment_checks,
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/management/base.py", line 377, in _run_checks
    return checks.run_checks(**kwargs)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/checks/registry.py", line 72, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/checks/urls.py", line 40, in check_url_namespaces_unique
    all_namespaces = _load_all_namespaces(resolver)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/core/checks/urls.py", line 57, in _load_all_namespaces
    url_patterns = getattr(resolver, 'url_patterns', [])
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/utils/functional.py", line 80, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/urls/resolvers.py", line 584, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/utils/functional.py", line 80, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/urls/resolvers.py", line 577, in urlconf_module
    return import_module(self.urlconf_name)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/peter/Documents/21q/locallibrary/urls.py", line 60, in <module>
    loader.load_db()
  File "/home/peter/Documents/21q/catalog/loader.py", line 106, in load_db
    add_game(*game, batch=True)
  File "/home/peter/Documents/21q/catalog/models.py", line 315, in add_game
    fault = add_fault(fault_name, batch=batch)
  File "/home/peter/Documents/21q/catalog/models.py", line 327, in add_fault
    fault = Fault.objects.get(fault__icontains = fault_name)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/models/query.py", line 402, in get
    num = len(clone)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/models/query.py", line 256, in __len__
    self._fetch_all()
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/models/query.py", line 1242, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/models/query.py", line 55, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1133, in execute_sql
    cursor.execute(sql, params)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/backends/utils.py", line 99, in execute
    return super().execute(sql, params)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/backends/utils.py", line 67, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/home/peter/.virtualenvs/21q_env/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 383, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such table: catalog_fault

我在 Stackoverflow 和其他網站上閱讀了很多問答，但無法解決問題。

我已經嘗試按照以下接受的答案中的步驟進行操作，但沒有任何區別： Django - no such table exception

幾個小時以來，我一直在努力解決這個問題，但我一無所獲。

感謝您的幫助！

Answer 1

哇，經過幾個小時的無處可去，我真的剛剛解決了它！

結果我試圖在數據庫准備好之前將數據加載到urls.py的 sqlite 數據庫中。

makemigrations在執行migrate之前觸發了loader.load_db()調用。 一旦我注釋掉loader.load_db()遷移工作完美！ :)

所以總而言之，請確保在執行makemigrations和migrate之前，您不會嘗試將任何數據加載到數據庫中。

Answer 2

您在模塊級別上有代碼，可以在堆棧中進一步執行查詢：

fault = Fault.objects.get(fault__icontains = fault_name)

在模塊級別，當makemigrations分析模塊時將執行此代碼，並且由於尚未創建數據庫表，因此結果查詢將失敗。

作為解決方案，您必須將該代碼放置在不會在導入時執行的位置，或者您必須處理引發的異常。

Answer 3

當我嘗試將基於函數的視圖更改為基於類的視圖時，我遇到了同樣的問題。 我嘗試通過調用數據庫查詢來分配類變量，以便它在創建實際表之前嘗試進行數據庫調用，在刪除此分配后， makemigrations工作得很好。

這是我的代碼示例，當我捕獲此錯誤時

class SampleView(LoginRequiredMixin, UpdateView):
    sample_variable = SampleModel.objects.get(active=True)

我解決這個問題的方式

class SampleView(LoginRequiredMixin, UpdateView):
    sample_variable = None

    def get_object(self, queryset=None):
        self.sample_variable = SampleModel.objects.get(active=True)
        return super(SampleView, self).get_object(queryset)

如果您遇到這樣的錯誤，請查看您的視圖，可能是同樣的錯誤導致了代碼中的錯誤。

就我而言，我將數據庫查詢和變量賦值移動到覆蓋 get 方法，並在初始化時將變量保留為None值

PS我在這個例子中覆蓋了get_object ，但是你可以將變量的賦值移動到一些不同的函數