TransactionManagementError - This is forbidden when an 'atomic' block is active

Question

While upgrading my project from django 1.5.1 to 1.6.5, I am facing this weird issue.

This is forbidden when an 'atomic' block is active.

I am aware of the Database Transaction changes for django 1.6 and made the setting changes accordingly. Works for most part, except when request.user object is accessed.

The code, for instance:

with transaction.atomic():
    if hasattr(request, 'user') and getattr(request.user, 'id', None):
        #blah

Here is the stacktrace:

Environment:


Request Method: GET
Request URL: <domain>/api/v1/browser_id/

Django Version: 1.6.5
Python Version: 2.7.3

<Installed Applications & Middlewares snipped for brevity>

Traceback:
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  112.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/transaction.py" in inner
  371.                 return func(*args, **kwargs)
File "/home/kravindra/workspace/puppysite/puppy/kennel/views/etag_session.py" in browser_id
  43.         if hasattr(request, 'user') and getattr(request.user, 'id', None):
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/utils/functional.py" in inner
  213.             self._setup()
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/utils/functional.py" in _setup
  298.         self._wrapped = self._setupfunc()
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/auth/middleware.py" in <lambda>
  18.         request.user = SimpleLazyObject(lambda: get_user(request))
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/auth/middleware.py" in get_user
  10.         request._cached_user = auth.get_user(request)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/auth/__init__.py" in get_user
  140.         user_id = request.session[SESSION_KEY]
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/sessions/backends/base.py" in __getitem__
  47.         return self._session[key]
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/sessions/backends/base.py" in _get_session
  173.                 self._session_cache = self.load()
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/sessions/backends/cached_db.py" in load
  52.                 self.create()
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/sessions/backends/db.py" in create
  40.                 self.save(must_create=True)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/sessions/backends/cached_db.py" in save
  62.         super(SessionStore, self).save(must_create)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/sessions/backends/db.py" in save
  63.                 obj.save(force_insert=must_create, using=using)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/models/base.py" in save
  545.                        force_update=force_update, update_fields=update_fields)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/models/base.py" in save_base
  582.                                    update_fields=update_fields, raw=raw, using=using)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/dispatch/dispatcher.py" in send
  185.             response = receiver(signal=self, sender=sender, **named)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/transaction.py" in inner
  430.             with self:
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/transaction.py" in __enter__
  422.         self.entering(self.using)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/transaction.py" in entering
  483.         enter_transaction_management(using=using)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/transaction.py" in enter_transaction_management
  70.     get_connection(using).enter_transaction_management(managed, forced)
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/backends/__init__.py" in enter_transaction_management
  287.         self.validate_no_atomic_block()
File "/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/db/backends/__init__.py" in validate_no_atomic_block
  367.                 "This is forbidden when an 'atomic' block is active.")

Exception Type: TransactionManagementError at /api/v1/browser_id/
Exception Value: This is forbidden when an 'atomic' block is active.

Looking at the stacktrace,

/usr/local/virtualenvs/karthik-django165/local/lib/python2.7/site-packages/django/contrib/sessions/backends/cached_db.py in load
                self.create() ...
▼ Local vars
Variable    Value
e   
DoesNotExist('Session matching query does not exist.',)
self    
<django.contrib.sessions.backends.cached_db.SessionStore object at 0x7f61d401c6d0>
data    
None

SessionStore raises an exception.

Using POSTGRES as the backend database. The backend session store related settings are:

SESSION_ENGINE = 'django.contrib.sessions.backends.cached_db' #which is persistent storage

ATOMIC_REQUESTS = True

Any pointers on how to fix this issue?

I found that there are a bunch of Questions on SO, and blogposts that address TransactionManagementError issue in general, but nothing to address this issue in particular

Answer 1

From the traceback it looks like one of your post_save signal receiver is still using one of the following deprecated transaction APIs:

• transaction.Transaction
• transaction.autocommit
• transaction.commit_on_success
• transaction.commit_manually
• commit_on_success_unless_managed

Make sure to replace it with a transaction.atomic instance instead and your issue should go away.

Let me know if you have trouble finding the culprit receiver.