当我运行测试用例时，出现此错误： psycopg2.OperationalError: cursor "_django_curs_140351416325888_23" does

Posted 2023-02-24

【中文标题】当我运行测试用例时，出现此错误： psycopg2.OperationalError: cursor "_django_curs_140351416325888_23" does not exist

【英文标题】：When I run test cases I get this error: psycopg2.OperationalError: cursor "_django_curs_140351416325888_23" does not exist

【发布时间】：2018-06-19 10:32:18

【问题描述】：

我正在尝试运行测试用例，但出现以下错误。

运行命令：python manage.py test

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

【问题讨论】：

您是否使用 inspectdb 命令从预先存在的表中生成模型？我遇到了同样的问题，发现要引入预先存在的数据，我可以通过允许 django 创建我的表然后将我的数据复制到其中来解决它。

这可能是几件事，包括与当前值冲突的约束规则修改等。如果它的开发环境没有数据库中的重要数据，最简单的解决方案是重新创建数据库

【参考方案1】：

就我而言，它发生在使用 PostgreSQL 的生产系统中，并且所有迁移都已完成。

将 DISABLE_SERVER_SIDE_CURSORS 设置为 True 修复我的错误：

DATABASES = 
    'default': 
        'ENGINE': 'django.db.backends.postgresql',
        'USER': 'db_user',
        'NAME': 'db_name',
        'DISABLE_SERVER_SIDE_CURSORS': True,   # <------ Only for PostgreSQL
    ,

【参考方案2】：

当我搞砸了在 Django 单元测试中使用非托管（在模型的 Meta 中使用 managed = False）模型时，我遇到了同样的问题。

解决方案是在执行单元测试时管理模型。

为了实现这一点，我必须在迁移中应用更改，如下所示：

        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
            ,
        ),

【参考方案3】：

遇到这个问题的时候，原来是因为我在模型中添加了字段，忘记了makemigrations和migrate。

在这种情况下，通常你会收到来自 Django 的警告，但由于某种原因我没有收到。

【讨论】：

我遇到了这个错误，运行 makemigrations 和 migrate 没有帮助，因为所有迁移都已创建并运行。

顺便说一句，当 Seb 说“原来是因为我在模型中添加了字段而忘记进行迁移和迁移”时，这包括模型中的任何更改。说真的，django 不在这里！即使你修改了模型字段的 help_text，你也会遇到这个问题。如果 makemigrations 和 migrate 没有帮助，那么查看您的文件差异，您肯定会发现您已经以某种方式、形状或形式修改了模型，从而影响了模型的数据库字段。祝你好运！