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import warnings
from django.core.exceptions import MiddlewareNotUsed
from django.db import connection, transaction
class TransactionMiddleware(object):
"""
Transaction middleware. If this is enabled, each view function will be run
with commit_on_response activated - that way a save() doesn't do a direct
commit, the commit is done when a successful response is created. If an
exception happens, the database is rolled back.
"""
def __init__(self):
warnings.warn(
"TransactionMiddleware is deprecated in favor of ATOMIC_REQUESTS.",
PendingDeprecationWarning, stacklevel=2)
if connection.settings_dict['ATOMIC_REQUESTS']:
raise MiddlewareNotUsed
def process_request(self, request):
"""Enters transaction management"""
transaction.enter_transaction_management()
def process_exception(self, request, exception):
"""Rolls back the database and leaves transaction management"""
if transaction.is_dirty():
# This rollback might fail because of network failure for example.
# If rollback isn't possible it is impossible to clean the
# connection's state. So leave the connection in dirty state and
# let request_finished signal deal with cleaning the connection.
transaction.rollback()
transaction.leave_transaction_management()
def process_response(self, request, response):
"""Commits and leaves transaction management."""
if not transaction.get_autocommit():
if transaction.is_dirty():
# Note: it is possible that the commit fails. If the reason is
# closed connection or some similar reason, then there is
# little hope to proceed nicely. However, in some cases (
# deferred foreign key checks for exampl) it is still possible
# to rollback().
try:
transaction.commit()
except Exception:
# If the rollback fails, the transaction state will be
# messed up. It doesn't matter, the connection will be set
# to clean state after the request finishes. And, we can't
# clean the state here properly even if we wanted to, the
# connection is in transaction but we can't rollback...
transaction.rollback()
transaction.leave_transaction_management()
raise
transaction.leave_transaction_management()
return response
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