Django can't drop database: psycopg2.OperationalError: cannot drop the current open database

Question

每当我尝试通过 manage.py 运行我的 Django 测试时，测试运行良好，但最后当 Django 销毁数据库时，会出现以下错误：

Destroying test database for alias 'default'...
Traceback (most recent call last):
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 62, in execute
    return self.cursor.execute(sql)
psycopg2.OperationalError: cannot drop the currently open database


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

Traceback (most recent call last):
  File "/Applications/PyCharm.app/Contents/helpers/pycharm/django_test_manage.py", line 129, in <module>
    utility.execute()
  File "/Applications/PyCharm.app/Contents/helpers/pycharm/django_test_manage.py", line 104, in execute
    PycharmTestCommand().run_from_argv(self.argv)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/core/management/commands/test.py", line 30, in run_from_argv
    super(Command, self).run_from_argv(argv)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/core/management/base.py", line 348, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/core/management/commands/test.py", line 74, in execute
    super(Command, self).execute(*args, **options)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/core/management/base.py", line 399, in execute
    output = self.handle(*args, **options)
  File "/Applications/PyCharm.app/Contents/helpers/pycharm/django_test_manage.py", line 91, in handle
    failures = TestRunner(test_labels, verbosity=verbosity, interactive=interactive, failfast=failfast, keepdb='--keepdb' in sys.argv)
  File "/Applications/PyCharm.app/Contents/helpers/pycharm/django_test_runner.py", line 256, in run_tests
    extra_tests=extra_tests, **options)
  File "/Applications/PyCharm.app/Contents/helpers/pycharm/django_test_runner.py", line 156, in run_tests
    return super(DjangoTeamcityTestRunner, self).run_tests(test_labels, extra_tests, **kwargs)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/test/runner.py", line 534, in run_tests
    self.teardown_databases(old_config)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/test/runner.py", line 509, in teardown_databases
    connection.creation.destroy_test_db(old_name, self.verbosity, self.keepdb)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/db/backends/base/creation.py", line 264, in destroy_test_db
    self._destroy_test_db(test_database_name, verbosity)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/db/backends/base/creation.py", line 283, in _destroy_test_db
    % self.connection.ops.quote_name(test_database_name))
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/db/utils.py", line 95, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 62, in execute
    return self.cursor.execute(sql)
django.db.utils.OperationalError: cannot drop the currently open database

我已经检查以确保没有其他任何东西连接到数据库 - 为什么 Django 不能删除数据库？

注意：我使用的是 PostgreSQL

Answer 1

TL;DR

如果您只是想要解决方案，这里就是。 确保您的 Postgres 服务器具有“postgres”数据库。您可以通过psql 连接并运行/list 或/l 来检查。您可以通过在 psql 中运行：CREATE DATABASE postgres 来创建数据库。

扩展

Django 不喜欢从DATABASES 设置中指定的“默认”数据库运行“初始化查询”（可能是创建测试数据库之类的事情）。这被认为是生产数据库，所以不要乱来，这符合 Django 的最佳利益。

这就是为什么在测试开始时会显示（忽略我的文件系统）：

    /Users/dcgoss/Desktop/Pickle/PickleBackend/venv/lib/python3.4/site-packages/django/db/backends/postgresql/base.py:247: 
    RuntimeWarning: Normally Django will use a connection to the 'postgres' database to avoid running initialization queries against the production database when it's not needed 
    (for example, when running tests). Django was unable to create a connection to the 'postgres' database and will use the default database instead.
    RuntimeWarning

Django 在您的DATABASES 设置中指定的主机上查找名为“postgres”的数据库，这是它运行查询以创建和删除您的测试数据库的地方。 （注意：Django 不需要在您的设置中明确指定“postgres”数据库，它只是在您的设置中指定的任何数据库服务器上查找它）。

如果这个“postgres”数据库不存在，Django 可以创建测试数据库并运行测试，但它不能删除测试数据库。这可能是因为 Postgres 不允许您删除当前连接的数据库，但是对我来说，似乎没有理由 Django 不能从指定的“默认”（生产）数据库中删除测试数据库设置。我认为它正在使用“默认”数据库来创建测试数据库，所以它似乎没有理由不能删除它。

无论如何，解决方案只是使用简单的 SQL 语句创建“postgres”数据库：CREATE DATABASE postgres。创建该数据库后，一切正常。

Answer 2

如果 postgres 数据库存在，请尝试在 pg_hba.conf 中添加对“postgres”数据库的访问权限。参考：https://www.postgresql.org/docs/9.1/static/auth-pg-hba-conf.html

Answer 3

如果您将 pgbouncer 与 postgresql 一起使用，您可能希望将 postgres 数据库添加到 pgbouncer.ini 文件中的数据库列表中