使用 MySQL 后端的事务在 Django 中不起作用
Transactions not working in Django using MySQL backend
我经常收到以下代码片段的完整性错误：
class StatsManager(Manager):
@transaction.atomic
def create(self, **kwargs):
kwargs.setdefault('date', date.today())
try:
obj = self.get_queryset().get(**kwargs)
except self.model.DoesNotExist:
obj = super().create(hits=1, **kwargs) # line 28
else:
obj.hits = F('hits') + 1
obj.save()
return obj
错误信息如下：
IntegrityError at /emploi/cours-particuliers-en-physique-chimie-en-classe-de-superieur-1-evry-14skb.html
(1062, "Duplicate entry 'EMP_VIEW-1903259-2018-01-08' for key 'statEvent'")
和回溯：
File "/home/www/aladom_v6/www/stats/models/managers.py" in create
26. obj = self.get_queryset().get(**kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/query.py" in get
380. self.model._meta.object_name
During handling of the above exception (Stats matching query does not exist.), another exception occurred:
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
65. return self.cursor.execute(sql, params)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django_mysql/monkey_patches.py" in execute
35. return orig_execute(self, sql, args)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/mysql/base.py" in execute
101. return self.cursor.execute(query, args)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
250. self.errorhandler(self, exc, value)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/connections.py" in defaulterrorhandler
50. raise errorvalue
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
247. res = self._query(query)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in _query
411. rowcount = self._do_query(q)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in _do_query
374. db.query(q)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/connections.py" in query
277. _mysql.connection.query(self, query)
The above exception ((1062, "Duplicate entry 'EMP_VIEW-1903259-2018-01-08' for key 'statEvent'")) was the direct cause of the following exception:
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/core/handlers/exception.py" in inner
41. response = get_response(request)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/core/handlers/base.py" in _get_response
187. response = self.process_exception_by_middleware(e, request)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/channels/handler.py" in process_exception_by_middleware
243. return super(AsgiHandler, self).process_exception_by_middleware(exception, request)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/core/handlers/base.py" in _get_response
185. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/views/generic/base.py" in view
68. return self.dispatch(request, *args, **kwargs)
File "/home/www/aladom_v6/www/utils/views/behaviors.py" in dispatch
343. return super().dispatch(request, *args, **kwargs)
File "/home/www/aladom_v6/www/offers/views/public.py" in dispatch
1089. return super().dispatch(request, *args, **kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/views/generic/base.py" in dispatch
88. return handler(request, *args, **kwargs)
File "/home/www/aladom_v6/www/offers/views/public.py" in get
1308. return super().get(request, *args, **kwargs)
File "/home/www/aladom_v6/www/stats/views/behaviors.py" in get
16. target_id=self.object.pk)
File "/usr/lib/python3.4/contextlib.py" in inner
30. return func(*args, **kwds)
File "/home/www/aladom_v6/www/stats/models/managers.py" in create
28. obj = super().create(hits=1, **kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/manager.py" in manager_method
85. return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/query.py" in create
394. obj.save(force_insert=True, using=self.db)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/base.py" in save
808. force_update=force_update, update_fields=update_fields)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/base.py" in save_base
838. updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/base.py" in _save_table
924. result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/base.py" in _do_insert
963. using=using, raw=raw)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/manager.py" in manager_method
85. return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/query.py" in _insert
1076. return query.get_compiler(using=using).execute_sql(return_id)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/sql/compiler.py" in execute_sql
1107. cursor.execute(sql, params)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
65. return self.cursor.execute(sql, params)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/utils.py" in __exit__
94. six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/utils/six.py" in reraise
685. raise value.with_traceback(tb)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
65. return self.cursor.execute(sql, params)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django_mysql/monkey_patches.py" in execute
35. return orig_execute(self, sql, args)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/mysql/base.py" in execute
101. return self.cursor.execute(query, args)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
250. self.errorhandler(self, exc, value)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/connections.py" in defaulterrorhandler
50. raise errorvalue
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
247. res = self._query(query)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in _query
411. rowcount = self._do_query(q)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in _do_query
374. db.query(q)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/connections.py" in query
277. _mysql.connection.query(self, query)
当我在上面检查密钥是否存在并将其封装在事务中时，第 28 行引发了重复输入错误。
我正在使用 Django 1.11，所以我尝试将 MySQL 隔离级别设置为 read committed。我以为它会解决这个问题，但它仍然发生。
我也试过反过来做：
class StatsManager(Manager):
def create(self, **kwargs):
kwargs.setdefault('date', date.today())
try:
obj = super().create(hits=1, **kwargs)
except IntegrityError:
obj = self.get_queryset().get(**kwargs) # line 27
obj.hits = F('hits') + 1
obj.save()
return obj
但在这种情况下，它有时会失败并出现以下错误，因为我的请求被封装在事务中：
TransactionManagementError at /admin/moderation/serviceoffermoderation/248424/change/
An error occurred in the current transaction. You can't execute queries until the end of the 'atomic' block.
这实际上是预期的，与前一个错误不同。
知道发生了什么事以及如何处理吗？
看来您可以重写代码以使用 get_or_create，它对竞争条件有一些处理。
为避免当前事务发生错误错误，需要将可以引发IntegrityError的代码用transaction.atomic包装起来：
def create(self, **kwargs):
kwargs.setdefault('date', date.today())
try:
with transaction.atomic():
obj = super().create(hits=1, **kwargs)
except IntegrityError:
obj = self.get_queryset().get(**kwargs) # line 27
obj.hits = F('hits') + 1
obj.save()
return obj
有关详细信息，请参阅 controlling transactions explicitly 上的文档。
我经常收到以下代码片段的完整性错误：
class StatsManager(Manager):
@transaction.atomic
def create(self, **kwargs):
kwargs.setdefault('date', date.today())
try:
obj = self.get_queryset().get(**kwargs)
except self.model.DoesNotExist:
obj = super().create(hits=1, **kwargs) # line 28
else:
obj.hits = F('hits') + 1
obj.save()
return obj
错误信息如下：
IntegrityError at /emploi/cours-particuliers-en-physique-chimie-en-classe-de-superieur-1-evry-14skb.html
(1062, "Duplicate entry 'EMP_VIEW-1903259-2018-01-08' for key 'statEvent'")
和回溯：
File "/home/www/aladom_v6/www/stats/models/managers.py" in create
26. obj = self.get_queryset().get(**kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/query.py" in get
380. self.model._meta.object_name
During handling of the above exception (Stats matching query does not exist.), another exception occurred:
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
65. return self.cursor.execute(sql, params)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django_mysql/monkey_patches.py" in execute
35. return orig_execute(self, sql, args)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/mysql/base.py" in execute
101. return self.cursor.execute(query, args)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
250. self.errorhandler(self, exc, value)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/connections.py" in defaulterrorhandler
50. raise errorvalue
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
247. res = self._query(query)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in _query
411. rowcount = self._do_query(q)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in _do_query
374. db.query(q)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/connections.py" in query
277. _mysql.connection.query(self, query)
The above exception ((1062, "Duplicate entry 'EMP_VIEW-1903259-2018-01-08' for key 'statEvent'")) was the direct cause of the following exception:
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/core/handlers/exception.py" in inner
41. response = get_response(request)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/core/handlers/base.py" in _get_response
187. response = self.process_exception_by_middleware(e, request)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/channels/handler.py" in process_exception_by_middleware
243. return super(AsgiHandler, self).process_exception_by_middleware(exception, request)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/core/handlers/base.py" in _get_response
185. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/views/generic/base.py" in view
68. return self.dispatch(request, *args, **kwargs)
File "/home/www/aladom_v6/www/utils/views/behaviors.py" in dispatch
343. return super().dispatch(request, *args, **kwargs)
File "/home/www/aladom_v6/www/offers/views/public.py" in dispatch
1089. return super().dispatch(request, *args, **kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/views/generic/base.py" in dispatch
88. return handler(request, *args, **kwargs)
File "/home/www/aladom_v6/www/offers/views/public.py" in get
1308. return super().get(request, *args, **kwargs)
File "/home/www/aladom_v6/www/stats/views/behaviors.py" in get
16. target_id=self.object.pk)
File "/usr/lib/python3.4/contextlib.py" in inner
30. return func(*args, **kwds)
File "/home/www/aladom_v6/www/stats/models/managers.py" in create
28. obj = super().create(hits=1, **kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/manager.py" in manager_method
85. return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/query.py" in create
394. obj.save(force_insert=True, using=self.db)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/base.py" in save
808. force_update=force_update, update_fields=update_fields)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/base.py" in save_base
838. updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/base.py" in _save_table
924. result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/base.py" in _do_insert
963. using=using, raw=raw)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/manager.py" in manager_method
85. return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/query.py" in _insert
1076. return query.get_compiler(using=using).execute_sql(return_id)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/models/sql/compiler.py" in execute_sql
1107. cursor.execute(sql, params)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
65. return self.cursor.execute(sql, params)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/utils.py" in __exit__
94. six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/utils/six.py" in reraise
685. raise value.with_traceback(tb)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
65. return self.cursor.execute(sql, params)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django_mysql/monkey_patches.py" in execute
35. return orig_execute(self, sql, args)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/django/db/backends/mysql/base.py" in execute
101. return self.cursor.execute(query, args)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
250. self.errorhandler(self, exc, value)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/connections.py" in defaulterrorhandler
50. raise errorvalue
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in execute
247. res = self._query(query)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in _query
411. rowcount = self._do_query(q)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/cursors.py" in _do_query
374. db.query(q)
File "/home/www/.virtualenvs/aladom/lib/python3.4/site-packages/MySQLdb/connections.py" in query
277. _mysql.connection.query(self, query)
当我在上面检查密钥是否存在并将其封装在事务中时，第 28 行引发了重复输入错误。
我正在使用 Django 1.11，所以我尝试将 MySQL 隔离级别设置为 read committed。我以为它会解决这个问题，但它仍然发生。
我也试过反过来做：
class StatsManager(Manager):
def create(self, **kwargs):
kwargs.setdefault('date', date.today())
try:
obj = super().create(hits=1, **kwargs)
except IntegrityError:
obj = self.get_queryset().get(**kwargs) # line 27
obj.hits = F('hits') + 1
obj.save()
return obj
但在这种情况下，它有时会失败并出现以下错误，因为我的请求被封装在事务中：
TransactionManagementError at /admin/moderation/serviceoffermoderation/248424/change/
An error occurred in the current transaction. You can't execute queries until the end of the 'atomic' block.
这实际上是预期的，与前一个错误不同。
知道发生了什么事以及如何处理吗？
看来您可以重写代码以使用 get_or_create，它对竞争条件有一些处理。
为避免当前事务发生错误错误，需要将可以引发IntegrityError的代码用transaction.atomic包装起来：
def create(self, **kwargs):
kwargs.setdefault('date', date.today())
try:
with transaction.atomic():
obj = super().create(hits=1, **kwargs)
except IntegrityError:
obj = self.get_queryset().get(**kwargs) # line 27
obj.hits = F('hits') + 1
obj.save()
return obj
有关详细信息，请参阅 controlling transactions explicitly 上的文档。