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[soc2009/multidb] Updated the transactions documentation for parts of the API that were extended to support multiple databases.

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git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2009/multidb@10937 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Alex Gaynor 2009-06-07 03:26:12 +00:00
parent fdd5ff646e
commit 110e4f68ef
1 changed files with 25 additions and 5 deletions
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docs/topics/db/transactions.txt
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@ -56,7 +56,10 @@ Controlling transaction management in views
For most people, implicit request-based transactions work wonderfully. However, For most people, implicit request-based transactions work wonderfully. However,
if you need more fine-grained control over how transactions are managed, you if you need more fine-grained control over how transactions are managed, you
can use Python decorators to change the way transactions are handled by a can use Python decorators to change the way transactions are handled by a
particular view function. particular view function. All of the decorators take an option ``using``
parameter which should be the alias for a database connection for which the
behavior applies to. If no alias is specified then the ``"default"`` database
is used.
.. note:: .. note::
@ -79,9 +82,14 @@ Example::
def viewfunc(request): def viewfunc(request):
.... ....
@transaction.autocommit(using="my_other_database")
def viewfunc2(request):
....
Within ``viewfunc()``, transactions will be committed as soon as you call Within ``viewfunc()``, transactions will be committed as soon as you call
``model.save()``, ``model.delete()``, or any other function that writes to the ``model.save()``, ``model.delete()``, or any other function that writes to the
database. database. ``viewfunc2()`` will have this same behavior, but for the
``"my_other_database"`` connection.
``django.db.transaction.commit_on_success`` ``django.db.transaction.commit_on_success``
------------------------------------------- -------------------------------------------
@ -95,6 +103,10 @@ all the work done in a function::
def viewfunc(request): def viewfunc(request):
.... ....
@transaction.commit_on_success(using="my_other_database")
def viewfunc2(request):
....
If the function returns successfully, then Django will commit all work done If the function returns successfully, then Django will commit all work done
within the function at that point. If the function raises an exception, though, within the function at that point. If the function raises an exception, though,
Django will roll back the transaction. Django will roll back the transaction.
@ -127,6 +139,10 @@ Manual transaction management looks like this::
else: else:
transaction.commit() transaction.commit()
@transaction.commit_manually(using="my_other_database")
def viewfunc2(request):
....
.. admonition:: An important note to users of earlier Django releases: .. admonition:: An important note to users of earlier Django releases:
The database ``connection.commit()`` and ``connection.rollback()`` methods The database ``connection.commit()`` and ``connection.rollback()`` methods
@ -169,21 +185,25 @@ issue a rollback, the entire transaction is rolled back. Savepoints provide
the ability to perform a fine-grained rollback, rather than the full rollback the ability to perform a fine-grained rollback, rather than the full rollback
that would be performed by ``transaction.rollback()``. that would be performed by ``transaction.rollback()``.
Each of these functions takes a ``using`` argument which should be the name of
a database for which the behavior applies. If no ``using`` argument is
provided then the ``"default"`` database is used.
Savepoints are controlled by three methods on the transaction object: Savepoints are controlled by three methods on the transaction object:
.. method:: transaction.savepoint() .. method:: transaction.savepoint(using=None)
Creates a new savepoint. This marks a point in the transaction that Creates a new savepoint. This marks a point in the transaction that
is known to be in a "good" state. is known to be in a "good" state.
Returns the savepoint ID (sid). Returns the savepoint ID (sid).
.. method:: transaction.savepoint_commit(sid) .. method:: transaction.savepoint_commit(sid, using=None)
Updates the savepoint to include any operations that have been performed Updates the savepoint to include any operations that have been performed
since the savepoint was created, or since the last commit. since the savepoint was created, or since the last commit.
.. method:: transaction.savepoint_rollback(sid) .. method:: transaction.savepoint_rollback(sid, using=None)
Rolls the transaction back to the last point at which the savepoint was Rolls the transaction back to the last point at which the savepoint was
committed. committed.