【问题标题】:Django: manage.py makemigrations --> django.db.utils.OperationalError: no such tableDjango:manage.py makemigrations --> django.db.utils.OperationalError:没有这样的表
【发布时间】:2020-04-26 09:28:20
【问题描述】:

我做了什么: - 删除了完整的数据库。 - 删除了迁移文件夹的内容

然后我做了: python manage.py makemigrations.

我收到上述错误消息。

我也做过: - 新鲜拉出 github 仓库 - 创建 venv - 激活 venv - 运行 python manage.py migrate

看起来好像 migrate 命令检查完整的源文件以查找对不存在的表的引用。我在这里没有想法。

错误:

python manage.py makemigrations
Traceback (most recent call last):
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 396, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: no such table: newshows_setting

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

Traceback (most recent call last):
  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/management/__init__.py", line 395, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/management/base.py", line 328, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/management/base.py", line 366, in execute
    self.check()
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/management/base.py", line 395, in check
    include_deployment_checks=include_deployment_checks,
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/management/base.py", line 382, in _run_checks
    return checks.run_checks(**kwargs)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/checks/registry.py", line 72, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/checks/urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/core/checks/urls.py", line 23, in check_resolver
    return check_method()
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/urls/resolvers.py", line 407, in check
    for pattern in self.url_patterns:
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/urls/resolvers.py", line 588, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/urls/resolvers.py", line 581, in urlconf_module
    return import_module(self.urlconf_name)
  File "/usr/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/harald/Projects/newshows/src/new_shows/urls.py", line 7, in <module>
    path('', include('newshows.urls')),
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/urls/conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "/usr/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/harald/Projects/newshows/src/newshows/urls.py", line 2, in <module>
    from . import views
  File "/home/harald/Projects/newshows/src/newshows/views.py", line 7, in <module>
    from .tables import ShowTable
  File "/home/harald/Projects/newshows/src/newshows/tables.py", line 8, in <module>
    class ShowTable(tables.Table):
  File "/home/harald/Projects/newshows/src/newshows/tables.py", line 12, in ShowTable
    class Meta:
  File "/home/harald/Projects/newshows/src/newshows/tables.py", line 13, in Meta
    settings = Setting.objects.get(id=1)
  File "/home/harald/Projects/newshows/.venv/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/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/models/query.py", line 411, in get
    num = len(clone)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/models/query.py", line 258, in __len__
    self._fetch_all()
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/models/query.py", line 1261, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/models/query.py", line 57, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1144, in execute_sql
    cursor.execute(sql, params)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 100, in execute
    return super().execute(sql, params)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "/home/harald/Projects/newshows/.venv/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 396, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such table: newshows_setting

【问题讨论】:

    标签: django django-migrations


    【解决方案1】:

    在您的堆栈跟踪中发现了问题:

      File "/home/harald/Projects/newshows/src/newshows/tables.py", line 13, in Meta
        settings = Setting.objects.get(id=1)
    

    这意味着当应用程序正在编译时,您正在代码中的某处运行Setting.objects.get(id=1)。这将在makemigrations 命令中进行实际迁移之前发生。重构你的代码来懒惰地调用是解决你的问题的方法。

    【讨论】:

    • 我如何懒惰地称呼它?
    • 这取决于您的代码以及之后如何使用settings
    • 通常是通过传递对函数的引用,该函数在调用时会提供Setting 实例,并且该函数仅在需要该实例时才会被调用。但是,我不知道这是否对你有用,因为我不知道上下文。
    • 在设置类中我保存所有应用程序设置。所以这在整个应用程序中都使用。
    • 我需要重构整个应用程序来改变它...... :(
    【解决方案2】:

    问题是,我试图访问一个尚不存在的查询集。我重构了整个代码以使用环境变量进行设置。

    【讨论】:

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