Django 迁移失败，使用新数据库

Django migrations failing with fresh database

提问人：Joe Davy 提问时间：10/2/2017 最后编辑：Joe Davy 更新时间：10/2/2017 访问量：448

问：

想知道是否有其他人在 Django 迁移中遇到令人沮丧的行为。我查看了 SO 上的几篇相关帖子，但没有找到任何专门针对此问题的内容。

这种情况不断发生在我身上，这一定是一个常见的场景，所以我错过了什么？

我的场景：

  1. 列表项
  2. 我已经构建了一个 Django 应用程序，在我的本地机器上使用 sqlite 进行迭代
  3. 我现在想部署到生产 Postgresql 数据库（AWS 或其他地方）
  4. 我设置了我的新数据库，将其添加到我的设置中，然后运行python manage.py migrate
  5. 我收到一个 SQL 错误，告诉我我的一个模型表不存在。咄！这就是我运行迁移的原因。
  6. 我最终不得不手工制作桌子，做一些奇怪的事情，比如这会给像这样的软件包带来进一步的问题python manage.py migrate <app_name> --fakesimple_history

我相信一定有一个显而易见的答案 - 我应该怎么做才能在全新的、干净的数据库上设置数据库模式？

编辑：我收到的错误回溯：

当我在空白数据库上运行时，出现以下错误：python manage.py migrate

(banzai-platform-django) ➜  src git:(master) ✗ ./manage.py migrate
Traceback (most recent call last):
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
psycopg2.ProgrammingError: relation "events_event" does not exist
LINE 1: ...ents_event"."created", "events_event"."slug" FROM "events_ev...
                                                             ^


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

Traceback (most recent call last):
  File "./manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/management/__init__.py", line 363, in execute_from_command_line
    utility.execute()
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/management/__init__.py", line 355, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/management/base.py", line 327, in execute
    self.check()
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/management/base.py", line 359, in check
    include_deployment_checks=include_deployment_checks,
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 62, in _run_checks
    issues.extend(super(Command, self)._run_checks(**kwargs))
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/management/base.py", line 346, in _run_checks
    return checks.run_checks(**kwargs)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/checks/registry.py", line 81, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/checks/urls.py", line 16, in check_url_config
    return check_resolver(resolver)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/core/checks/urls.py", line 26, in check_resolver
    return check_method()
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/urls/resolvers.py", line 254, in check
    for pattern in self.url_patterns:
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/utils/functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/urls/resolvers.py", line 405, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/utils/functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/urls/resolvers.py", line 398, in urlconf_module
    return import_module(self.urlconf_name)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 978, in _gcd_import
  File "<frozen importlib._bootstrap>", line 961, in _find_and_load
  File "<frozen importlib._bootstrap>", line 950, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 205, in _call_with_frames_removed
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/src/banzai_platform/urls.py", line 67, in <module>
    url(r'^registrations/', include('registrations.urls')),
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/conf/urls/__init__.py", line 50, in include
    urlconf_module = import_module(urlconf_module)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 978, in _gcd_import
  File "<frozen importlib._bootstrap>", line 961, in _find_and_load
  File "<frozen importlib._bootstrap>", line 950, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 205, in _call_with_frames_removed
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/src/registrations/urls.py", line 3, in <module>
    from .views import (
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/src/registrations/views.py", line 160, in <module>
    class ConfirmEventListView(ListView):
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/src/registrations/views.py", line 164, in ConfirmEventListView
    queryset = [obj for obj in events if obj.need_confirmation > 0]
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/models/query.py", line 250, in __iter__
    self._fetch_all()
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/models/query.py", line 1118, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/models/query.py", line 53, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 894, in execute_sql
    raise original_exception
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 884, in execute_sql
    cursor.execute(sql, params)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/backends/utils.py", line 80, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/Users/joedavy/Dropbox/Apps/banzai-platform-django/lib/python3.6/site-packages/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: relation "events_event" does not exist
LINE 1: ...ents_event"."created", "events_event"."slug" FROM "events_ev...
django postgresql django-migrations

评论

0赞 Daniel Roseman 10/2/2017
部署时不应运行 makemigrations。在开发时运行 makemigrations。
0赞 Daniel Roseman 10/2/2017
但是，如果出现错误，则应将其与完整的回溯一起发布。
0赞 Joe Davy 10/2/2017
@DanielRoseman - 澄清一下，我的第一个想法是运行 manage.py 迁移，但这给出了同样的错误。我已将错误+回溯添加到帖子中，以防有帮助。
0赞 Joe Davy 10/2/2017
其他说明 - 我正在运行 Django v1.11.4

答：

2赞 Daniel Roseman 10/2/2017 #1

回溯显示，你正在 ConfirmEventListView 内的类级别对查询集运行列表推导式。首次导入类时，将执行类级别的任何内容;因此，此查询会立即执行任何 Django 命令，这是在迁移有机会运行之前。

绝不能执行任何访问此级别数据库的操作。（老实说，你根本不应该做这个列表推导，因为它返回的是列表而不是查询集;所以它不适用于分页或其他需要实际查询集的东西。但是，由于您的代码的其余部分可以正常工作，因此我们可以假设这在您的情况下还不是问题。

如果是字段，则查询集应定义为 。但是，如果它是模型方法，则应在 ConfirmEventListView 上定义一个方法，并在那里执行此处理，而不是在类级别执行此处理。need_confirmationEvent.objects.filter(need_confirmation__gt=0)get_queryset()

评论

0赞 Joe Davy 10/2/2017
非常感谢 - 这解释了为什么我收到错误。那么类中的方法，例如没有计算？ 是一个模型方法，用@property声明。关于如何返回查询集而不是基于模型方法的列表筛选的任何指导？get_queryset()need_confirmation
1赞 Daniel Roseman 10/2/2017
区别在于，它是作为请求的一部分调用的，而不是在定义时调用的。事实上，正如刚才在另一个问题上向我指出的那样，从该方法返回列表是完全有效的;因此，只需将该列表 comp 移动到方法中并返回它，一切都应该很好。get_queryset
0赞 Joe Davy 10/2/2017
太棒了 - 做到了，现在似乎一切都在起作用。

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