OperationalError: no such table but database and migrations folder were deleted

Question

与此非常相似question:

我有一个脚本：

将所有数据转储到json、
删除 database.sqlite3 文件和 migrations 文件夹
执行：
1. python 制作迁移应用程序
2. python manage.py 迁移应用程序
3. python manage.py makemigrations
4. python manage.py 迁移
加载来自json

我在开发东西和经常重新启动时经常使用它。现在即使是 makemigrations app 命令也会失败并显示 OperationalError: no such table.

有趣的是，当我注释掉这个 table 的所有外观时（但模型仍在 models.py 中），一切正常。如果我然后删除评论一切正常。我错过了什么？

回溯：

PS ..\projectname> python manage.py migrate appname       
Traceback (most recent call last):
  File "..\venv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "..\venv\lib\site-packages\django\db\backends\sqlite3\base.py", line 423, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: no such table: appname_unmigrateablemodel

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

Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    main()
  File "manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "..\venv\lib\site-packages\django\core\management\__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "..\venv\lib\site-packages\django\core\management\__init__.py", line 413, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "..\venv\lib\site-packages\django\core\management\base.py", line 354, in run_from_argv
    self.execute(*args, **cmd_options)
  File "..\venv\lib\site-packages\django\core\management\base.py", line 398, in execute
    output = self.handle(*args, **options)
  File "..\venv\lib\site-packages\django\core\management\base.py", line 89, in wrapped
    res = handle_func(*args, **kwargs)
  File "..\venv\lib\site-packages\django\core\management\commands\migrate.py", line 75, in handle
    self.check(databases=[database])
  File "..\venv\lib\site-packages\django\core\management\base.py", line 419, in check
    all_issues = checks.run_checks(
  File "..\venv\lib\site-packages\django\core\checks\registry.py", line 76, in run_checks
    new_errors = check(app_configs=app_configs, databases=databases)
  File "..\venv\lib\site-packages\django\core\checks\urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "..\venv\lib\site-packages\django\core\checks\urls.py", line 23, in check_resolver
    return check_method()
  File "..\venv\lib\site-packages\django\urls\resolvers.py", line 412, in check
    for pattern in self.url_patterns:
  File "..\venv\lib\site-packages\django\utils\functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "..\venv\lib\site-packages\django\urls\resolvers.py", line 598, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "..\venv\lib\site-packages\django\utils\functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "..\venv\lib\site-packages\django\urls\resolvers.py", line 591, in urlconf_module
    return import_module(self.urlconf_name)
  File "C:\Python38\lib\importlib\__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "..\projectname\projectname\urls.py", line 24, in <module>
    path('', include('appname.urls')), ## must be the last ! line in the URLS file because of the empty argument #
  File "..\venv\lib\site-packages\django\urls\conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "C:\Python38\lib\importlib\__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "..\projectname\appname\urls.py", line 2, in <module>
    from . import views
  File "..\projectname\appname\views.py", line 15, in <module>
    from .external.server_api import APISERVICE
  File "..\projectname\appname\external\hiveserver_api.py", line 10, in <module>
    USB_ETHERNET_ADAPTER_MAC_LIST = [A.mac for A in unmigrateablemodel.objects.all()]
  File "..\venv\lib\site-packages\django\db\models\query.py", line 280, in __iter__
    self._fetch_all()
  File "..\venv\lib\site-packages\django\db\models\query.py", line 1324, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "..\venv\lib\site-packages\django\db\models\query.py", line 51, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "..\venv\lib\site-packages\django\db\models\sql\compiler.py", line 1175, in execute_sql
    cursor.execute(sql, params)
  File "..\venv\lib\site-packages\django\db\backends\utils.py", line 98, in execute
    return super().execute(sql, params)
  File "..\venv\lib\site-packages\django\db\backends\utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "..\venv\lib\site-packages\django\db\backends\utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "..\venv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "..\venv\lib\site-packages\django\db\utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "..\venv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "..\venv\lib\site-packages\django\db\backends\sqlite3\base.py", line 423, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such table: appname_unmigrateablemodel

Answer 1

回溯中的这一部分：

File "..\projectname\appname\views.py", line 15, in <module>
    from .external.server_api import APISERVICE
File "..\projectname\appname\external\hiveserver_api.py", line 10, in <module>
    USB_ETHERNET_ADAPTER_MAC_LIST = [A.mac for A in unmigrateablemodel.objects.all()]

告诉我们您正在 hiveserver_api.py 模块的导入期间进行查询。

由于空数据库中没有表，导入该模块总是会失败，它是通过views导入的，它是通过urls导入的，因为应用程序在INSTALLED_APPS.

您需要重构该代码，使其在导入时不执行该查询，或者只是暂时执行：

USB_ETHERNET_ADAPTER_MAC_LIST = []

这也意味着您的应用程序中存在错误； MAC 地址列表将永远不会在您的视图中更新until/unless 应用程序已重新加载。

顺便说一句，

USB_ETHERNET_ADAPTER_MAC_LIST = list(
    unmigrateablemodel.objects.all().values_list("mac", flat=True)
)

是做同样事情的有效方法。

OperationalError: no such table but database and migrations folder were deleted

OperationalError: no such table but database and migrations folder were deleted

django

django-models

django-migrations