首次部署Django项目至Heroku遇django_content_type表不存在错误

问题描述 #

首次将Django项目部署到Heroku，执行以下操作时出现异常：

• 用户注册/登录功能无法正常使用
• 执行heroku run python manage.py makemigrations失败
• 执行heroku run python manage.py migrate（含--fake参数）报错

错误信息 #

Traceback (most recent call last):
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
psycopg2.errors.UndefinedTable: relation "django_content_type" does not exist
LINE 1: ..."."app_label", "django_content_type"."model" FROM "django_co...
                                                             ^


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

Traceback (most recent call last):
  File "/app/manage.py", line 22, in <module>
    main()
  File "/app/manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/core/management/__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "/app/.heroku/python/lib/python3.10/site-packages/django/core/management/__init__.py", line 413, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/core/management/base.py", line 354, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/core/management/base.py", line 398, in execute
    output = self.handle(*args, **options)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/core/management/base.py", line 89, in wrapped
    res = handle_func(*args, **kwargs)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/core/management/commands/migrate.py", line 268, in handle
    emit_post_migrate_signal(
  File "/app/.heroku/python/lib/python3.10/site-packages/django/core/management/sql.py", line 42, in emit_post_migrate_signal
    models.signals.post_migrate.send(
  File "/app/.heroku/python/lib/python3.10/site-packages/django/dispatch/dispatcher.py", line 180, in send
    return [
  File "/app/.heroku/python/lib/python3.10/site-packages/django/dispatch/dispatcher.py", line 181, in <listcomp>
    (receiver, receiver(signal=self, sender=sender, **named))
  File "/app/.heroku/python/lib/python3.10/site-packages/django/contrib/auth/management/__init__.py", line 42, in create_permissions
    create_contenttypes(app_config, verbosity=verbosity, interactive=interactive, using=using, apps=apps, **kwargs)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/contrib/contenttypes/management/__init__.py", line 119, in create_contenttypes
    content_types, app_models = get_contenttypes_and_models(app_config, using, ContentType)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/contrib/contenttypes/management/__init__.py", line 94, in get_contenttypes_and_models
    content_types = {
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/models/query.py", line 280, in __iter__
    self._fetch_all()
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/models/query.py", line 1324, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/models/query.py", line 51, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/models/sql/compiler.py", line 1175, in execute_sql
    cursor.execute(sql, params)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/backends/utils.py", line 98, in execute
    return super().execute(sql, params)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/backends/utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/backends/utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/backends/utils.py", line 79, in _execute
    with self.db.wrap_database_errors:
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/app/.heroku/python/lib/python3.10/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: relation "django_content_type" does not exist
LINE 1: ..."."app_label", "django_content_type"."model" FROM "django_co...

环境与配置信息 #

• 本地原使用db.sqlite3数据库
• settings.py核心配置：

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django_elasticsearch_dsl',
    'psycopg2',
    'malbucket'
]

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgres',
    }
}
DATABASES["default"] = dj_database_url.config(default=urllib.parse.quote(os.environ.get("DATABASE_URL", "").encode("utf-8")))

当前数据库状态 #

执行manage.py dbshell后显示的表列表：

List of relations
 Schema |       Name        | Type  |     Owner      
--------+-------------------+-------+----------------
 public | django_migrations | table | <name>
 public | django_session    | table | <name>

迁移标记状态 #

执行heroku run python manage.py showmigrations结果：

admin
 [X] 0001_initial
 [X] 0002_logentry_remove_auto_add
 [X] 0003_logentry_add_action_flag_choices
auth
 [X] 0001_initial
 [X] 0002_alter_permission_name_max_length
 [X] 0003_alter_user_email_max_length
 [X] 0004_alter_user_username_opts
 [X] 0005_alter_user_last_login_null
 [X] 0006_require_contenttypes_0002
 [X] 0007_alter_validators_add_error_messages
 [X] 0008_alter_user_username_max_length
 [X] 0009_alter_user_last_name_max_length
 [X] 0010_alter_group_name_max_length
 [X] 0011_update_proxy_permissions
 [X] 0012_alter_user_first_name_max_length
contenttypes
 [X] 0001_initial
 [X] 0002_remove_content_type_name
sessions
 [X] 0001_initial

解决方案 #

1. 重置数据库迁移记录 #

进入Heroku PostgreSQL数据库shell：

heroku pg:psql

删除迁移记录表中的所有记录：

DELETE FROM django_migrations;

退出数据库shell：

\q

2. 修正数据库引擎配置 #

修改settings.py中的数据库引擎，将postgres改为postgresql（Django官方标准写法）：

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
    }
}

修改后重新部署代码到Heroku：

git add settings.py
git commit -m "fix database engine typo"
git push heroku main

3. 按依赖顺序重新执行迁移 #

先迁移contenttypes（它是auth、admin等应用的核心依赖）：

heroku run python manage.py migrate contenttypes

接着依次迁移其他核心应用：

heroku run python manage.py migrate auth
heroku run python manage.py migrate admin
heroku run python manage.py migrate sessions

最后迁移自定义应用和第三方应用：

heroku run python manage.py migrate malbucket

4. 修复迁移标记（若仍有不一致） #

如果showmigrations显示迁移已标记为应用，但实际表不存在，执行以下命令：

heroku run python manage.py migrate --fake-initial

5. 验证修复结果 #

执行命令检查django_content_type表是否存在：

heroku run python manage.py inspectdb | grep django_content_type

或进入数据库shell查看全量表列表：

heroku pg:psql
\dt

内容的提问来源于stack exchange，提问作者Finch