Question

模块级别（也称为导入时间）的数据库查询可能会在django中造成麻烦。

请参阅：https://groups.google.com/forum/#!topic/django-developers/7JwWatLfP44/discussion

故障：

在测试中访问真正的数据库，而不是测试数据库。
在应用就绪信号中修补猴子为时已晚
...

如何在应用就绪信号发生之前检测访问我的数据库的特定python源代码？

Answer 1

我找到了解决方案。它很“脏”，但有效。

如果您将assert 0添加到get_new_connection

的django/db/backends/postgresql/base.py

然后你会看到很长的追溯。它会显示您过早访问数据库的位置。

当然，您应该只在开发环境中执行此操作。

我猜大致相同的应该适用于sqlite。

foobar_vums_d@aptguettler:~$ py.test -k ...
Traceback (most recent call last):
  File "/home/foobar_vums_d/bin/py.test", line 11, in <module>
    sys.exit(main())
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/_pytest/config.py", line 49, in main
    return config.hook.pytest_cmdline_main(config=config)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/_pytest/vendored_packages/pluggy.py", line 724, in __call__
    return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/_pytest/vendored_packages/pluggy.py", line 338, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/_pytest/vendored_packages/pluggy.py", line 333, in <lambda>
    _MultiCall(methods, kwargs, hook.spec_opts).execute()
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/_pytest/vendored_packages/pluggy.py", line 596, in execute
    res = hook_impl.function(*args)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/pytest_djangotools/hooks.py", line 46, in pytest_cmdline_main
    import consolescript_django
  File "/home/foobar_vums_d/src/djangotools/consolescript_django/__init__.py", line 11, in <module>
    django.setup()
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/apps/registry.py", line 115, in populate
    app_config.ready()
  File "/home/foobar_vums_d/src/djangotools/djangotools/apps.py", line 19, in ready
    url_patterns = get_resolver(None).url_patterns
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/utils/functional.py", line 33, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/core/urlresolvers.py", line 417, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/utils/functional.py", line 33, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/core/urlresolvers.py", line 410, in urlconf_module
    return import_module(self.urlconf_name)
  File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "/home/foobar_vums_d/src/foobar-vums/foobar_vums/etc/rooturls.py", line 11, in <module>
    urlpatterns = collect_urlpatterns_from_apps()
  File "/home/foobar_vums_d/src/djangotools/djangotools/utils/urlresolverutils.py", line 124, in collect_urlpatterns_from_apps
    urls_module = importlib.import_module(app_import_string + '.urls')
  File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "/home/foobar_vums_d/src/foobar/foobar/urls.py", line 310, in <module>
    urlpatterns.append(url(r'^', include(collect_urlpatterns_from_package(views))))
  File "/home/foobar_vums_d/src/djangotools/djangotools/utils/urlresolverutils.py", line 94, in collect_urlpatterns_from_package
    import_package(views_package)
  File "/home/foobar_vums_d/src/djangotools/djangotools/utils/urlresolverutils.py", line 89, in import_package
    importlib.import_module(module_name)
  File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "/home/foobar_vums_d/src/foobar/foobar/views/issue/legacy_edit2.py", line 55, in <module>
    for index in Index.objects.all():
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/models/query.py", line 258, in __iter__
    self._fetch_all()
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/models/query.py", line 1074, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/models/query.py", line 52, in __iter__
    results = compiler.execute_sql()
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 846, in execute_sql
    cursor = self.connection.cursor()
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 231, in cursor
    cursor = self.make_debug_cursor(self._cursor())
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 204, in _cursor
    self.ensure_connection()
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 199, in ensure_connection
    self.connect()
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 171, in connect
    self.connection = self.get_new_connection(conn_params)
  File "/home/foobar_vums_d/local/lib/python2.7/site-packages/django/db/backends/postgresql/base.py", line 175, in get_new_connection
    connection = Database.connect(**conn_params)
  File "/usr/lib/python2.7/dist-packages/psycopg2/__init__.py", line 105, in connect
    assert 0
AssertionError

在这种情况下，有缺陷的行在src/foobar/foobar/views/issue/legacy_edit2.py

您可以通过从下到上跳过堆栈来找到这一点，跳过包含/site-packages/django/的所有行。

Django：检测模块级数据库查询

1 个答案: