============================================ Django 1.5 release notes - UNDER DEVELOPMENT ============================================ These release notes cover the `new features`_, as well as some `backwards incompatible changes`_ you'll want to be aware of when upgrading from Django 1.4 or older versions. We've also dropped some features, which are detailed in :doc:`our deprecation plan `, and we've `begun the deprecation process for some features`_. .. _`new features`: `What's new in Django 1.5`_ .. _`backwards incompatible changes`: `Backwards incompatible changes in 1.5`_ .. _`begun the deprecation process for some features`: `Features deprecated in 1.5`_ Python compatibility ==================== Django 1.5 has dropped support for Python 2.5. Python 2.6.5 is now the minimum required Python version. Django is tested and supported on Python 2.6 and 2.7. This change should affect only a small number of Django users, as most operating-system vendors today are shipping Python 2.6 or newer as their default version. If you're still using Python 2.5, however, you'll need to stick to Django 1.4 until you can upgrade your Python version. Per :doc:`our support policy `, Django 1.4 will continue to receive security support until the release of Django 1.6. Django 1.5 does not run on a Jython final release, because Jython's latest release doesn't currently support Python 2.6. However, Jython currently does offer an alpha release featuring 2.7 support. What's new in Django 1.5 ======================== Support for saving a subset of model's fields ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The method :meth:`Model.save() ` has a new keyword argument ``update_fields``. By using this argument it is possible to save only a select list of model's fields. This can be useful for performance reasons or when trying to avoid overwriting concurrent changes. Deferred instances (those loaded by .only() or .defer()) will automatically save just the loaded fields. If any field is set manually after load, that field will also get updated on save. See the :meth:`Model.save() ` documentation for more details. Caching of related model instances ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When traversing relations, the ORM will avoid re-fetching objects that were previously loaded. For example, with the tutorial's models:: >>> first_poll = Poll.objects.all()[0] >>> first_choice = first_poll.choice_set.all()[0] >>> first_choice.poll is first_poll True In Django 1.5, the third line no longer triggers a new SQL query to fetch ``first_choice.poll``; it was set by the second line. For one-to-one relationships, both sides can be cached. For many-to-one relationships, only the single side of the relationship can be cached. This is particularly helpful in combination with ``prefetch_related``. ``{% verbatim %}`` template tag ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To make it easier to deal with javascript templates which collide with Django's syntax, you can now use the :ttag:`verbatim` block tag to avoid parsing the tag's content. Retrieval of ``ContentType`` instances associated with proxy models ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The methods :meth:`ContentTypeManager.get_for_model() ` and :meth:`ContentTypeManager.get_for_models() ` have a new keyword argument – respectively ``for_concrete_model`` and ``for_concrete_models``. By passing ``False`` using this argument it is now possible to retreive the :class:`ContentType ` associated with proxy models. New ``view`` variable in class-based views context ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In all :doc:`generic class-based views ` (or any class-based view inheriting from ``ContextMixin``), the context dictionary contains a ``view`` variable that points to the ``View`` instance. Minor features ~~~~~~~~~~~~~~ Django 1.5 also includes several smaller improvements worth noting: * The template engine now interprets ``True``, ``False`` and ``None`` as the corresponding Python objects. * :mod:`django.utils.timezone` provides a helper for converting aware datetimes between time zones. See :func:`~django.utils.timezone.localtime`. * The generic views support OPTIONS requests. * Management commands do not raise ``SystemExit`` any more when called by code from :ref:`call_command `. Any exception raised by the command (mostly :ref:`CommandError `) is propagated. * The dumpdata management command outputs one row at a time, preventing out-of-memory errors when dumping large datasets. * In the localflavor for Canada, "pq" was added to the acceptable codes for Quebec. It's an old abbreviation. * The :ref:`receiver ` decorator is now able to connect to more than one signal by supplying a list of signals. * :meth:`QuerySet.bulk_create() ` now has a batch_size argument. By default the batch_size is unlimited except for SQLite where single batch is limited so that 999 parameters per query isn't exceeded. Backwards incompatible changes in 1.5 ===================================== .. warning:: In addition to the changes outlined in this section, be sure to review the :doc:`deprecation plan ` for any features that have been removed. If you haven't updated your code within the deprecation timeline for a given feature, its removal may appear as a backwards incompatible change. Context in year archive class-based views ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For consistency with the other date-based generic views, :class:`~django.views.generic.dates.YearArchiveView` now passes ``year`` in the context as a :class:`datetime.date` rather than a string. If you are using ``{{ year }}`` in your templates, you must replace it with ``{{ year|date:"Y" }}``. ``next_year`` and ``previous_year`` were also added in the context. They are calculated according to ``allow_empty`` and ``allow_future``. Context in TemplateView ~~~~~~~~~~~~~~~~~~~~~~~ For consistency with the design of the other generic views, :class:`~django.views.generic.base.TemplateView` no longer passes a ``params`` dictionary into the context, instead passing the variables from the URLconf directly into the context. OPTIONS, PUT and DELETE requests in the test client ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Unlike GET and POST, these HTTP methods aren't implemented by web browsers. Rather, they're used in APIs, which transfer data in various formats such as JSON or XML. Since such requests may contain arbitrary data, Django doesn't attempt to decode their body. However, the test client used to build a query string for OPTIONS and DELETE requests like for GET, and a request body for PUT requests like for POST. This encoding was arbitrary and inconsistent with Django's behavior when it receives the requests, so it was removed in Django 1.5. If you were using the ``data`` parameter in an OPTIONS or a DELETE request, you must convert it to a query string and append it to the ``path`` parameter. If you were using the ``data`` parameter in a PUT request without a ``content_type``, you must encode your data before passing it to the test client and set the ``content_type`` argument. .. _simplejson-incompatibilities: System version of :mod:`simplejson` no longer used ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ :ref:`As explained below `, Django 1.5 deprecates :mod:`django.utils.simplejson` in favor of Python 2.6's built-in :mod:`json` module. In theory, this change is harmless. Unfortunately, because of incompatibilities between versions of :mod:`simplejson`, it may trigger errors in some circumstances. JSON-related features in Django 1.4 always used :mod:`django.utils.simplejson`. This module was actually: - A system version of :mod:`simplejson`, if one was available (ie. ``import simplejson`` works), if it was more recent than Django's built-in copy or it had the C speedups, or - The :mod:`json` module from the standard library, if it was available (ie. Python 2.6 or greater), or - A built-in copy of version 2.0.7 of :mod:`simplejson`. In Django 1.5, those features use Python's :mod:`json` module, which is based on version 2.0.9 of :mod:`simplejson`. There are no known incompatibilities between Django's copy of version 2.0.7 and Python's copy of version 2.0.9. However, there are some incompatibilities between other versions of :mod:`simplejson`: - While the :mod:`simplejson` API is documented as always returning unicode strings, the optional C implementation can return a byte string. This was fixed in Python 2.7. - :class:`simplejson.JSONEncoder` gained a ``namedtuple_as_object`` keyword argument in version 2.2. More information on these incompatibilities is available in `ticket #18023`_. The net result is that, if you have installed :mod:`simplejson` and your code uses Django's serialization internals directly -- for instance :class:`django.core.serializers.json.DjangoJSONEncoder`, the switch from :mod:`simplejson` to :mod:`json` could break your code. (In general, changes to internals aren't documented; we're making an exception here.) At this point, the maintainers of Django believe that using :mod:`json` from the standard library offers the strongest guarantee of backwards-compatibility. They recommend to use it from now on. .. _ticket #18023: https://code.djangoproject.com/ticket/18023#comment:10 String types of hasher method parameters ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If you have written a :ref:`custom password hasher `, your ``encode()``, ``verify()`` or ``safe_summary()`` methods should accept Unicode parameters (``password``, ``salt`` or ``encoded``). If any of the hashing methods need byte strings, you can use the :func:`~django.utils.encoding.force_bytes` utility to encode the strings. Validation of previous_page_number and next_page_number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When using :doc:`object pagination `, the ``previous_page_number()`` and ``next_page_number()`` methods of the :class:`~django.core.paginator.Page` object did not check if the returned number was inside the existing page range. It does check it now and raises an :exc:`InvalidPage` exception when the number is either too low or too high. Behavior of autocommit database option on PostgreSQL changed ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PostgreSQL's autocommit option didn't work as advertised previously. It did work for single transaction block, but after the first block was left the autocommit behavior was never restored. This bug is now fixed in 1.5. While this is only a bug fix, it is worth checking your applications behavior if you are using PostgreSQL together with the autocommit option. Session not saved on 500 responses ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Django's session middleware will skip saving the session data if the response's status code is 500. Changes in tests execution ~~~~~~~~~~~~~~~~~~~~~~~~~~ Some changes have been introduced in the execution of tests that might be backward-incompatible for some testing setups: Database flushing in ``django.test.TransactionTestCase`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Previously, the test database was truncated *before* each test run in a :class:`~django.test.TransactionTestCase`. In order to be able to run unit tests in any order and to make sure they are always isolated from each other, :class:`~django.test.TransactionTestCase` will now reset the database *after* each test run instead. No more implict DB sequences reset ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ :class:`~django.test.TransactionTestCase` tests used to reset primary key sequences automatically together with the database flushing actions described above. This has been changed so no sequences are implicitly reset. This can cause :class:`~django.test.TransactionTestCase` tests that depend on hard-coded primary key values to break. The new :attr:`~django.test.TransactionTestCase.reset_sequences` attribute can be used to force the old behavior for :class:`~django.test.TransactionTestCase` that might need it. Ordering of tests ^^^^^^^^^^^^^^^^^ In order to make sure all ``TestCase`` code starts with a clean database, tests are now executed in the following order: * First, all unittests (including :class:`unittest.TestCase`, :class:`~django.test.SimpleTestCase`, :class:`~django.test.TestCase` and :class:`~django.test.TransactionTestCase`) are run with no particular ordering guaranteed nor enforced among them. * Then any other tests (e.g. doctests) that may alter the database without restoring it to its original state are run. This should not cause any problems unless you have existing doctests which assume a :class:`~django.test.TransactionTestCase` executed earlier left some database state behind or unit tests that rely on some form of state being preserved after the execution of other tests. Such tests are already very fragile, and must now be changed to be able to run independently. `cleaned_data` dictionary kept for invalid forms ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The :attr:`~django.forms.Form.cleaned_data` dictionary is now always present after form validation. When the form doesn't validate, it contains only the fields that passed validation. You should test the success of the validation with the :meth:`~django.forms.Form.is_valid()` method and not with the presence or absence of the :attr:`~django.forms.Form.cleaned_data` attribute on the form. Miscellaneous ~~~~~~~~~~~~~ * GeoDjango dropped support for GDAL < 1.5 * :func:`~django.utils.http.int_to_base36` properly raises a :exc:`TypeError` instead of :exc:`ValueError` for non-integer inputs. * The ``slugify`` template filter is now available as a standard python function at :func:`django.utils.text.slugify`. Similarly, ``remove_tags`` is available at :func:`django.utils.html.remove_tags`. Features deprecated in 1.5 ========================== .. _simplejson-deprecation: ``django.utils.simplejson`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Since Django 1.5 drops support for Python 2.5, we can now rely on the :mod:`json` module being available in Python's standard library, so we've removed our own copy of :mod:`simplejson`. You should now import :mod:`json` instead :mod:`django.utils.simplejson`. Unfortunately, this change might have unwanted side-effects, because of incompatibilities between versions of :mod:`simplejson` -- see the :ref:`backwards-incompatible changes ` section. If you rely on features added to :mod:`simplejson` after it became Python's :mod:`json`, you should import :mod:`simplejson` explicitly. ``itercompat.product`` ~~~~~~~~~~~~~~~~~~~~~~ The :func:`~django.utils.itercompat.product` function has been deprecated. Use the built-in :func:`itertools.product` instead. ``django.utils.encoding.StrAndUnicode`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The :class:`~django.utils.encoding.StrAndUnicode` mix-in has been deprecated. Define a ``__str__`` method and apply the :func:`~django.utils.encoding.python_2_unicode_compatible` decorator instead. ``django.utils.markup`` ~~~~~~~~~~~~~~~~~~~~~~~ The markup contrib module has been deprecated and will follow an accelerated deprecation schedule. Direct use of python markup libraries or 3rd party tag libraries is preferred to Django maintaining this functionality in the framework.