Ticket #14051: transaction_signals.patch

new file django/db/signals.py

@@ +1 @@
+from django.dispatch import Signal
+
+pre_commit = Signal()
+post_commit = Signal()
+
+pre_rollback = Signal()
+post_rollback = Signal()

django/db/transaction.py

@@ -21 +21 @@
 except ImportError:
     from django.utils.functional import wraps  # Python 2.4 fallback.
 from django.db import connections, DEFAULT_DB_ALIAS
+from django.db.signals import pre_commit, post_commit, pre_rollback, post_rollback
 from django.conf import settings
 
 class TransactionManagementError(Exception):
@@ -195 +196 @@
     """
     if using is None:
         using = DEFAULT_DB_ALIAS
+
+    pre_commit.send(sender=using)
     connection = connections[using]
     connection._commit()
     set_clean(using=using)
+    post_commit.send(sender=using)
 
 def rollback(using=None):
     """
@@ -205 +209 @@
     """
     if using is None:
         using = DEFAULT_DB_ALIAS
+
+    pre_rollback.send(sender=using)
+
     connection = connections[using]
     connection._rollback()
     set_clean(using=using)
+    post_rollback.send(sender=using)
+
 
 def savepoint(using=None):
     """

docs/ref/signals.txt

@@ -327 +327 @@
 ``sender``
     The model class which was just prepared.
 
+
+Transaction signals
+===================
+
+.. module:: django.db.signals
+   :synopsis: Signals sent when database transactions are committed/rolled back.
+
+The :mod:`django.db.signals` module defines a set of signals sent by the
+transaction system. These signals are sent even if you are not using a transaction
+capable database. See the :doc:`database transaction documentation </topics/db/transactions>`
+for more information about database transactions.
+
+
+pre_commit
+--------
+
+.. attribute:: django.db.signals.pre_commit
+   :module:
+
+.. ^^^^^^^ this :module: hack keeps Sphinx from prepending the module.
+
+Before a transaction is committed to the database, this signal is sent.
+
+Arguments sent with this signal:
+
+    ``sender``
+        The database connection alias where the transaction is to be committed.
+
+post_commit
+---------
+
+.. data:: django.db.signals.post_commit
+   :module:
+
+Like pre_commit, but this one is sent after the transaction has been committed.
+
+Arguments sent with this signal:
+
+    ``sender``
+        As above: The database connection alias.
+
+
+pre_rollback
+--------
+
+.. attribute:: django.db.signals.pre_rollback
+   :module:
+
+.. ^^^^^^^ this :module: hack keeps Sphinx from prepending the module.
+
+Before a transaction is being rollbacked the database, this signal is sent.
+
+Arguments sent with this signal:
+
+    ``sender``
+        The database connection alias where the transaction is to be rollbacked.
+
+
+post_rollback
+---------
+
+.. data:: django.db.signals.post_rollback
+   :module:
+
+Like pre_rollback, but this one is sent after the transaction has been rollbacked.
+
+Arguments sent with this signal:
+
+    ``sender``
+        As above: The database connection alias.
+
+
 Management signals
 ==================
 

tests/modeltests/transactions/models.py

@@ -22 +22 @@
 
 __test__ = {'API_TESTS':"""
 >>> from django.db import connection, transaction
+>>> from django.db.signals import pre_commit, post_commit, pre_rollback, post_rollback
 """}
 
 from django.conf import settings
@@ -129 +130 @@
     ...
 TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK
 
+# Make sure transaction signals is sent
+
+>>> def transaction_signal_test(signal, sender, **kwargs):
+...    signals = {
+...        pre_commit: 'pre_commit',
+...        post_commit: 'post_commit',
+...        pre_rollback: 'pre_rollback',
+...        post_rollback: 'post_rollback'
+...    }
+...
+...    print "signal: ", signals.get(signal)
+...    print 'sender: ', sender
+
+>>> pre_commit.connect(transaction_signal_test)
+>>> post_commit.connect(transaction_signal_test)
+>>> pre_rollback.connect(transaction_signal_test)
+>>> post_rollback.connect(transaction_signal_test)
+
+>>> transaction.commit()
+signal:  pre_commit
+sender:  default
+signal:  post_commit
+sender:  default
+
+>>> transaction.rollback()
+signal:  pre_rollback
+sender:  default
+signal:  post_rollback
+sender:  default
+
 """
 
+
 # Regression for #11900: If a function wrapped by commit_on_success writes a
 # transaction that can't be committed, that transaction should be rolled back.
 # The bug is only visible using the psycopg2 backend, though