============================================ 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 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 Jython, because Jython doesn't currently offer any version compatible with Python 2.6. 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. 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``. 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. 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``. 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. Features deprecated in 1.5 ========================== ``django.utils.simplejson`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Since Django 1.5 drops support for Python 2.5, we can now rely on the :mod:`json` module being in Python's standard library -- so we've removed our own copy of ``simplejson``. You can safely change any use of :mod:`django.utils.simplejson` to :mod:`json`. ``itercompat.product`` ~~~~~~~~~~~~~~~~~~~~~~ The :func:`~django.utils.itercompat.product` function has been deprecated. Use the built-in :func:`itertools.product` instead.