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当我运行测试用例时，出现以下错误：psycopg2.OperationalError: 游标“_django_curs_140351416325888_23”不存在。

pythondjangopostgresqldjango-tests
40

我正在尝试运行测试用例，但是出现以下错误。

运行命令 ：python manage.py test


（Translated from English）
Type 'yes' if you would like to try deleting the test database 'test_project_management_db', or 'no' to cancel: yes
Destroying old test database for alias 'default'...

Traceback (most recent call last):
  File "manage.py", line 24, in <module>
    execute_from_command_line(sys.argv)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 363, in execute_from_command_line
    utility.execute()
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 355, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/core/management/commands/test.py", line 29, in run_from_argv
    super(Command, self).run_from_argv(argv)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/core/management/base.py", line 330, in execute
    output = self.handle(*args, **options)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/core/management/commands/test.py", line 62, in handle
    failures = test_runner.run_tests(test_labels)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/test/runner.py", line 601, in run_tests
    old_config = self.setup_databases()
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/test/runner.py", line 546, in setup_databases
    self.parallel, **kwargs
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/test/utils.py", line 187, in setup_databases
    serialize=connection.settings_dict.get('TEST', {}).get('SERIALIZE', True),
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/db/backends/base/creation.py", line 77, in create_test_db
    self.connection._test_serialized_contents = self.serialize_db_to_string()
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/db/backends/base/creation.py", line 121, in serialize_db_to_string
    serializers.serialize("json", get_objects(), indent=None, stream=out)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/core/serializers/__init__.py", line 129, in serialize
    s.serialize(queryset, **options)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/core/serializers/base.py", line 80, in serialize
    for count, obj in enumerate(queryset, start=1):
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/db/backends/base/creation.py", line 117, in get_objects
    for obj in queryset.iterator():
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/db/models/query.py", line 53, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch)
  File "/home/rails/Desktop/projects/envs/project_manage_env/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 880, in execute_sql
    cursor.close()
psycopg2.OperationalError: cursor "_django_curs_140351416325888_23" does not exist
1
你是用inspectdb命令从现有的表中生成模型吗？我也遇到了同样的问题，发现可以通过允许Django创建我的表，然后将数据复制到其中来解决预先存在的数据的问题。 - JwM
可能有几个原因，包括与当前值冲突的约束规则修改等。如果这是一个没有重要数据的开发环境，则最简单的解决方案是重新创建数据库。 - stelios
4个回答
95

当我遇到这个问题时，原来是因为我向一个模型添加了字段，但忘记了执行makemigrations和migrate命令。

通常情况下，如果出现这种情况，Django会发出警告，但由于某种原因我没有收到任何警告。

3
我遇到了这个错误，运行makemigrations和migrate都没有帮助，因为所有的迁移都已经被创建并运行了。 - Stuart Axon
1
顺便说一下，当Seb说“结果是因为我向模型添加了字段并忘记了进行makemigrations和migrate”，这包括对模型的任何更改。 说真的，Django在这里不是闹着玩的！即使您修改了模型字段的help_text，也会出现此问题。如果makemigrations和migrate没有帮助，请查看文件差异，您肯定会发现您以某种方式修改了模型，形状或形式影响了模型的数据库字段。祝你好运！ - rgenito
10
在我的情况下，这发生在一个已经完成所有迁移的PostgreSQL生产系统上。
将DISABLE_SERVER_SIDE_CURSORS设置为True可以解决我的错误：
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'USER': 'db_user',
        'NAME': 'db_name',
        'DISABLE_SERVER_SIDE_CURSORS': True,   # <------ Only for PostgreSQL
    },
}
3

当我试图在Django的单元测试中使用未受管制的模型（即在模型的Meta中设置managed=False）时，遇到了同样的问题。

解决方法是在执行单元测试时使模型受管制。

为了实现这一点，我不得不对迁移进行更改，例如：

        migrations.CreateModel(
            name='UmnamagedModelName',
            fields=[
                ('uuid', models.TextField(primary_key=True, serialize=False)),
                # ...
                ('csms_updated', models.NullBooleanField()),
            ],
            options={
                'db_table': 'umnamage_table_name',
                'managed': running_tests(),  # <= this function returns True when running tests
            },
        ),
0
我刚刚在Django 2.2.28中遇到了这个问题，结果发现我的迁移文件命名不正确，带有一个`.py.py`的扩展名。纠正后，测试顺利通过运行。
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