Django + MySQL - 管理站点 - 添加用户 - OperationalError - SAVEPOINT 不存在

Question

我们正在尝试自定义 User 模型和行为，但随后我们注意到，即使是默认的 Django 安装在通过 Django Admin 添加新用户时也会出现问题：

该问题甚至在其他 Django 版本中也会发生（在 Django 1.8和最新版本 Django 1.11.3 中尝试过）。令人惊讶的是，使用 SQLite 或 PostgreSQL 数据库时不会发生此问题。此外，通过$./manage.py createuser和 以编程方式添加用户将起作用。admin通过终端编辑现有用途（如先前创建的超级用户）也将起作用。Group 的 CRUD 机制按预期工作，因此只有Add User视图会受到影响。

可能的故障点包括Django 核心（任何版本）、MySQL 二进制文件（捆绑在 XAMPP for Mac 中，也尝试过各种版本）或MySQL-Python连接器（版本 1.2.5）。类似的问题在这里，使用 Django 1.10和 MySQL。

复制步骤：

1. 安装最新的 Django 版本： $ pip install django

2. 安装 Python-MySQL 驱动程序： $ pip install MySQL-python

3. 创建一个新项目： $ django-admin.py startproject sandbox

4. 在 MySQL 中创建一个新数据库并在其中设置 db 配置 settings.py

5. 迁移 Django 应用程序的模型： $ ./manage.py migrate

6. 创建admin超级用户： $ ./manage.py createsuperuser

7. 运行 Django 的捆绑服务器： $ ./manage.py runserver

8. 转到http://127.0.0.1:8000/admin/login，并使用admin超级用户凭据登录。

9. 尝试单击用户的添加按钮。屏幕截图中附加的错误将被触发。

示例数据库查询日志：

Query   SET NAMES utf8
Query   set autocommit=1
Query   SELECT `django_session`.`session_key`, `django_session`.`session_data`, `django_session`.`expire_date` FROM `django_session` WHERE (`django_session`.`session_key` = 'ikql6mk9voxq4g0go9avuvuxxrpvwx9w' AND `django_session`.`expire_date` > '2017-07-10 06:58:15.823513')
Query   SELECT `auth_user`.`id`, `auth_user`.`password`, `auth_user`.`last_login`, `auth_user`.`is_superuser`, `auth_user`.`username`, `auth_user`.`first_name`, `auth_user`.`last_name`, `auth_user`.`email`, `auth_user`.`is_staff`, `auth_user`.`is_active`, `auth_user`.`date_joined` FROM `auth_user` WHERE `auth_user`.`id` = 1
Query   SAVEPOINT `s123145414516736_x1`
Query   RELEASE SAVEPOINT `s123145414516736_x1`
Query   ROLLBACK TO SAVEPOINT `s123145414516736_x1`
Query   rollback
Query   set autocommit=1
Quit

似乎在 SAVEPOINT RELEASE 之后 SAVEPOINT ROLLBACK 已经完成，导致 SAVEPOINT 丢失。基于MySQL 的 SavePoint 文档，自然顺序似乎是 ROLLBACK 然后 RELEASE。

这是回溯消息。settings.py除了用于连接到 MySQL 服务器的数据库配置/凭据外，Django 的默认设置没有其他更改：

Environment:


Request Method: GET
Request URL: http://127.0.0.1:8000/admin/auth/user/add/

Django Version: 1.11.3
Python Version: 2.7.8
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']



Traceback:

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/core/handlers/exception.py" in inner
  41.             response = get_response(request)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/contrib/admin/options.py" in wrapper
  551.                 return self.admin_site.admin_view(view)(*args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  149.                     response = view_func(request, *args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  57.         response = view_func(request, *args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/contrib/admin/sites.py" in inner
  224.             return view(request, *args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapper
  67.             return bound_func(*args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/views/decorators/debug.py" in sensitive_post_parameters_wrapper
  76.             return view(request, *args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in bound_func
  63.                 return func.__get__(self, type(self))(*args2, **kwargs2)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapper
  67.             return bound_func(*args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  149.                     response = view_func(request, *args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in bound_func
  63.                 return func.__get__(self, type(self))(*args2, **kwargs2)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/contrib/auth/admin.py" in add_view
  103.             return self._add_view(request, form_url, extra_context)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/contrib/auth/admin.py" in _add_view
  131.                                                extra_context)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/contrib/admin/options.py" in add_view
  1508.         return self.changeform_view(request, None, form_url, extra_context)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapper
  67.             return bound_func(*args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  149.                     response = view_func(request, *args, **kwargs)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/utils/decorators.py" in bound_func
  63.                 return func.__get__(self, type(self))(*args2, **kwargs2)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/contrib/admin/options.py" in changeform_view
  1408.             return self._changeform_view(request, object_id, form_url, extra_context)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/db/transaction.py" in __exit__
  210.                                 connection.savepoint_rollback(sid)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/db/backends/base/base.py" in savepoint_rollback
  348.         self._savepoint_rollback(sid)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/db/backends/base/base.py" in _savepoint_rollback
  308.             cursor.execute(self.ops.savepoint_rollback_sql(sid))

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
  80.             return super(CursorDebugWrapper, self).execute(sql, params)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
  65.                 return self.cursor.execute(sql, params)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/db/utils.py" in __exit__
  94.                 six.reraise(dj_exc_type, dj_exc_value, traceback)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
  63.                 return self.cursor.execute(sql)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/django/db/backends/mysql/base.py" in execute
  101.             return self.cursor.execute(query, args)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/MySQLdb/cursors.py" in execute
  205.             self.errorhandler(self, exc, value)

File "/Users/ranelpadon/.virtualenvs/django__1_11/lib/python2.7/site-packages/MySQLdb/connections.py" in defaulterrorhandler
  36.     raise errorclass, errorvalue

Exception Type: OperationalError at /admin/auth/user/add/
Exception Value: (1305, 'SAVEPOINT s123145452511232_x1 does not exist')

Answer 1

这个错误困扰了我很长时间，所以我决定进一步挖掘并尝试一劳永逸地解决它。

根本原因：SAVEPOINT 问题是仅在MySQL-Python连接器中发生的错误。

修复：为 Python 使用其他 MySQL 驱动程序（例如mysqlclient）。

详情/调查结果：

• 在 Mac 的 Homebrew、MAMP 和 XAMPP 中尝试了 MySQL 二进制文件。
• 尝试了各种 MySQL 版本，5.6 ( libmysqlclient.18.dylib) 和 5.7 ( libmysqlclient.20.dylib)。
• 尝试了各种 Python 的 MySQL 驱动程序。

通过改变 MySQL 二进制文件/版本没有发现任何关系。但是我通过测试 Python 中常用的各种 MySQL 驱动程序缩小了问题的范围：

1. MySQLdb（广泛使用但旧的数据库连接器，最后一次提交是在 7 年前！）：

   $ pip install MySQL-python

2. mysqlclient（现代版本MySQL-python，但有很多错误修复和改进）：

   $ pip install mysqlclient

3. PyMySQL（纯 Python MySQL 数据库驱动程序）：

   $ pip install PyMySQL

   然后，添加settings.py（就在 下方import os）：

   try:
       import pymysql
       pymysql.install_as_MySQLdb()
   except:
       pass
   

4. Oracle 的MySQL-Connector-Python（纯 Python MySQL 数据库驱动程序）：

   $ pip install mysql-connector-python-rf

   然后，编辑数据库的ENGINE配置settings.py：

   'ENGINE': 'mysql.connector.django',
   

SAVEPOINT 问题仅在使用MySQL-python连接器（#1 驱动程序）时发生，而在其他（#2、#3、#4 驱动程序）中不会发生。就我而言，我选择了mysqlclient。现在问题消失了。