==============================Django 1.4 alpha release notes==============================

December 22, 2011.

Welcome to Django 1.4 alpha!

This is the first in a series of preview/development releases leading up tothe eventual release of Django 1.4, scheduled for March 2012. This release isprimarily targeted at developers who are interested in trying out new featuresand testing the Django codebase to help identify and resolve bugs prior to thefinal 1.4 release.

As such, this release is *not* intended for production use, and any such useis discouraged.

Django 1.4 alpha includes various `new features`_ and some minor `backwardsincompatible changes`_. There are also some features that have been dropped,which are detailed in :doc:`our deprecation plan </internals/deprecation>`,and we've `begun the deprecation process for some features`_.

.. _new features: `What's new in Django 1.4`_

.. _backwards incompatible changes: `Backwards incompatible changes in 1.4`_

.. _begun the deprecation process for some features: `Features deprecated in 1.4`_

Python compatibility====================

While not a new feature, it's important to note that Django 1.4 introduces thesecond shift in our Python compatibility policy since Django's initial publicdebut. Django 1.2 dropped support for Python 2.3; now Django 1.4 drops supportfor Python 2.4. As such, the minimum Python version required for Django is now2.5, and Django is tested and supported on Python 2.5, 2.6 and 2.7.

This change should affect only a small number of Django users, as mostoperating-system vendors today are shipping Python 2.5 or newer as their defaultversion. If you're still using Python 2.4, however, you'll need to stick toDjango 1.3 until you can upgrade; per :doc:`our support policy</internals/release-process>`, Django 1.3 will continue to receive securitysupport until the release of Django 1.5.

Django does not support Python 3.x at this time. A document outlining our fulltimeline for deprecating Python 2.x and moving to Python 3.x will be publishedbefore the release of Django 1.4.

What's new in Django 1.4========================

Support for in-browser testing frameworks~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.4 supports integration with in-browser testing frameworks likeSelenium_. The new :class:`django.test.LiveServerTestCase` base class lets youtest the interactions between your site's front and back ends morecomprehensively. See the:class:`documentation<django.test.LiveServerTestCase>` for more details andconcrete examples.

.. _Selenium: http://seleniumhq.org/

``SELECT FOR UPDATE`` support~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.4 now includes a :meth:`QuerySet.select_for_update()<django.db.models.query.QuerySet.select_for_update>` method which generates a``SELECT ... FOR UPDATE`` SQL query. This will lock rows until the end of thetransaction, meaning that other transactions cannot modify or delete rowsmatched by a ``FOR UPDATE`` query.

For more details, see the documentation for:meth:`~django.db.models.query.QuerySet.select_for_update`.

``Model.objects.bulk_create`` in the ORM~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This method allows for more efficient creation of multiple objects in the ORM.It can provide significant performance increases if you have many objects.Django makes use of this internally, meaning some operations (such as databasesetup for test suites) have seen a performance benefit as a result.

See the :meth:`~django.db.models.query.QuerySet.bulk_create` docs for moreinformation.

``QuerySet.prefetch_related``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Similar to :meth:`~django.db.models.query.QuerySet.select_related` but with adifferent strategy and broader scope,:meth:`~django.db.models.query.QuerySet.prefetch_related` has been added to:class:`~django.db.models.query.QuerySet`. This method returns a new``QuerySet`` that will prefetch each of the specified related lookups in asingle batch as soon as the query begins to be evaluated. Unlike``select_related``, it does the joins in Python, not in the database, andsupports many-to-many relationships,:class:`~django.contrib.contenttypes.generic.GenericForeignKey` and more. Thisallows you to fix a very common performance problem in which your code ends updoing O(n) database queries (or worse) if objects on your primary ``QuerySet``each have many related objects that you also need.

Improved password hashing~~~~~~~~~~~~~~~~~~~~~~~~~

Django's auth system (``django.contrib.auth``) stores passwords using a one-wayalgorithm. Django 1.3 uses the SHA1_ algorithm, but increasing processor speedsand theoretical attacks have revealed that SHA1 isn't as secure as we'd like.Thus, Django 1.4 introduces a new password storage system: by default Django nowuses the PBKDF2_ algorithm (as recommended by NIST_). You can also easily choosea different algorithm (including the popular bcrypt_ algorithm). For moredetails, see :ref:`auth_password_storage`.

.. _sha1: http://en.wikipedia.org/wiki/SHA1

.. _pbkdf2: http://en.wikipedia.org/wiki/PBKDF2

.. _nist: http://csrc.nist.gov/publications/nistpubs/800-132/nist-sp800-132.pdf

.. _bcrypt: http://en.wikipedia.org/wiki/Bcrypt

HTML5 Doctype~~~~~~~~~~~~~

We've switched the admin and other bundled templates to use the HTML5doctype. While Django will be careful to maintain compatibility with olderbrowsers, this change means that you can use any HTML5 features you need inadmin pages without having to lose HTML validity or override the providedtemplates to change the doctype.

List filters in admin interface~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Prior to Django 1.4, the :mod:`~django.contrib.admin` app allowed you to specifychange list filters by specifying a field lookup, but didn't allow you to createcustom filters. This has been rectified with a simple API (previously usedinternally and known as "FilterSpec"). For more details, see the documentationfor :attr:`~django.contrib.admin.ModelAdmin.list_filter`.

Multiple sort in admin interface~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The admin change list now supports sorting on multiple columns. It respects allelements of the :attr:`~django.contrib.admin.ModelAdmin.ordering` attribute, andsorting on multiple columns by clicking on headers is designed to mimic thebehavior of desktop GUIs. The:meth:`~django.contrib.admin.ModelAdmin.get_ordering` method for specifying theordering dynamically (e.g. depending on the request) has also been added.

New ``ModelAdmin`` methods~~~~~~~~~~~~~~~~~~~~~~~~~~

A new :meth:`~django.contrib.admin.ModelAdmin.save_related` method was added to:mod:`~django.contrib.admin.ModelAdmin` to ease customization of howrelated objects are saved in the admin.

Two other new methods,:meth:`~django.contrib.admin.ModelAdmin.get_list_display` and:meth:`~django.contrib.admin.ModelAdmin.get_list_display_links`were added to :class:`~django.contrib.admin.ModelAdmin` to enable the dynamiccustomization of fields and links displayed on the admin change list.

Admin inlines respect user permissions~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Admin inlines will now only allow those actions for which the user haspermission. For ``ManyToMany`` relationships with an auto-created intermediatemodel (which does not have its own permissions), the change permission for therelated model determines if the user has the permission to add, change ordelete relationships.

Tools for cryptographic signing~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.4 adds both a low-level API for signing values and a high-level APIfor setting and reading signed cookies, one of the most common uses ofsigning in Web applications.

See the :doc:`cryptographic signing </topics/signing>` docs for moreinformation.

Cookie-based session backend~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.4 introduces a new cookie-based backend for the session frameworkwhich uses the tools for :doc:`cryptographic signing </topics/signing>` tostore the session data in the client's browser.

See the :ref:`cookie-based session backend <cookie-session-backend>` docs formore information.

New form wizard~~~~~~~~~~~~~~~

The previous ``FormWizard`` from the formtools contrib app has beenreplaced with a new implementation based on the class-based viewsintroduced in Django 1.3. It features a pluggable storage API and doesn'trequire the wizard to pass around hidden fields for every previous step.

Django 1.4 ships with a session-based storage backend and a cookie-basedstorage backend. The latter uses the tools for:doc:`cryptographic signing </topics/signing>` also introduced inDjango 1.4 to store the wizard's state in the user's cookies.

See the :doc:`form wizard </ref/contrib/formtools/form-wizard>` docs formore information.

``reverse_lazy``~~~~~~~~~~~~~~~~

A lazily evaluated version of :func:`django.core.urlresolvers.reverse` wasadded to allow using URL reversals before the project's URLConf gets loaded.

Translating URL patterns~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.4 gained the ability to look for a language prefix in the URL patternwhen using the new :func:`~django.conf.urls.i18n.i18n_patterns` helper function.Additionally, it's now possible to define translatable URL patterns using:func:`~django.utils.translation.ugettext_lazy`. See:ref:`url-internationalization` for more information about the language prefixand how to internationalize URL patterns.

Contextual translation support for ``{% trans %}`` and ``{% blocktrans %}``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :ref:`contextual translation<contextual-markers>` support introduced inDjango 1.3 via the ``pgettext`` function has been extended to the:ttag:`trans` and :ttag:`blocktrans` template tags using the new ``context``keyword.

Customizable ``SingleObjectMixin`` URLConf kwargs~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Two new attributes,:attr:`pk_url_kwarg<django.views.generic.detail.SingleObjectMixin.pk_url_kwarg>`and:attr:`slug_url_kwarg<django.views.generic.detail.SingleObjectMixin.slug_url_kwarg>`,have been added to :class:`~django.views.generic.detail.SingleObjectMixin` toenable the customization of URLConf keyword arguments used for singleobject generic views.

Assignment template tags~~~~~~~~~~~~~~~~~~~~~~~~

A new :ref:`assignment_tag<howto-custom-template-tags-assignment-tags>` helperfunction was added to ``template.Library`` to ease the creation of templatetags that store data in a specified context variable.

``*args`` and ``**kwargs`` support for template tag helper functions~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :ref:`simple_tag<howto-custom-template-tags-simple-tags>`,:ref:`inclusion_tag <howto-custom-template-tags-inclusion-tags>` andnewly introduced:ref:`assignment_tag<howto-custom-template-tags-assignment-tags>` templatehelper functions may now accept any number of positional or keyword arguments.For example:

.. code-block:: python

@register.simple_tag def my_tag(a, b, *args, **kwargs): warning = kwargs['warning'] profile = kwargs['profile'] ... return ...

Then in the template any number of arguments may be passed to the template tag.For example:

.. code-block:: html+django

{% my_tag 123 "abcd" book.title warning=message|lower profile=user.profile %}

No wrapping of exceptions in ``TEMPLATE_DEBUG`` mode~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In previous versions of Django, whenever the :setting:`TEMPLATE_DEBUG` settingwas ``True``, any exception raised during template rendering (even exceptionsunrelated to template syntax) were wrapped in ``TemplateSyntaxError`` andre-raised. This was done in order to provide detailed template source locationinformation in the debug 500 page.

In Django 1.4, exceptions are no longer wrapped. Instead, the originalexception is annotated with the source information. This means that catchingexceptions from template rendering is now consistent regardless of the value of:setting:`TEMPLATE_DEBUG`, and there's no need to catch and unwrap``TemplateSyntaxError`` in order to catch other errors.

``truncatechars`` template filter~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Added a filter which truncates a string to be no longer than the specifiednumber of characters. Truncated strings end with a translatable ellipsissequence ("..."). See the documentation for :tfilter:`truncatechars` formore details.

``static`` template tag~~~~~~~~~~~~~~~~~~~~~~~

The :mod:`staticfiles<django.contrib.staticfiles>` contrib app has a new:ttag:`static<staticfiles-static>` template tag to refer to files saved withthe :setting:`STATICFILES_STORAGE` storage backend. It uses the storagebackend's ``url`` method and therefore supports advanced features such as:ref:`serving files from a cloud service<staticfiles-from-cdn>`.

``CachedStaticFilesStorage`` storage backend~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In addition to the `static template tag`_, the:mod:`staticfiles<django.contrib.staticfiles>` contrib app now has a:class:`~django.contrib.staticfiles.storage.CachedStaticFilesStorage` backendwhich caches the files it saves (when running the :djadmin:`collectstatic`management command) by appending the MD5 hash of the file's content to thefilename. For example, the file ``css/styles.css`` would also be saved as``css/styles.55e7cbb9ba48.css``

See the :class:`~django.contrib.staticfiles.storage.CachedStaticFilesStorage`docs for more information.

Simple clickjacking protection~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We've added a middleware to provide easy protection against `clickjacking<http://en.wikipedia.org/wiki/Clickjacking>`_ using the ``X-Frame-Options``header. It's not enabled by default for backwards compatibility reasons, butyou'll almost certainly want to :doc:`enable it </ref/clickjacking/>` to helpplug that security hole for browsers that support the header.

CSRF improvements~~~~~~~~~~~~~~~~~

We've made various improvements to our CSRF features, including the:func:`~django.views.decorators.csrf.ensure_csrf_cookie` decorator which canhelp with AJAX heavy sites, protection for PUT and DELETE requests, and the:setting:`CSRF_COOKIE_SECURE` and :setting:`CSRF_COOKIE_PATH` settings which canimprove the security and usefulness of the CSRF protection. See the :doc:`CSRFdocs </ref/contrib/csrf>` for more information.

Error report filtering~~~~~~~~~~~~~~~~~~~~~~

Two new function decorators, :func:`sensitive_variables` and:func:`sensitive_post_parameters`, were added to allow designating thelocal variables and POST parameters which may contain sensitiveinformation and should be filtered out of error reports.

All POST parameters are now systematically filtered out of error reports forcertain views (``login``, ``password_reset_confirm``, ``password_change``, and``add_view`` in :mod:`django.contrib.auth.views`, as well as``user_change_password`` in the admin app) to prevent the leaking of sensitiveinformation such as user passwords.

You may override or customize the default filtering by writing a :ref:`customfilter<custom-error-reports>`. For more information see the docs on:ref:`Filtering error reports<filtering-error-reports>`.

Extended IPv6 support~~~~~~~~~~~~~~~~~~~~~

The previously added support for IPv6 addresses when using the runservermanagement command in Django 1.3 has now been further extended by addinga :class:`~django.db.models.GenericIPAddressField` model field,a :class:`~django.forms.GenericIPAddressField` form field andthe validators :data:`~django.core.validators.validate_ipv46_address` and:data:`~django.core.validators.validate_ipv6_address`

Updated default project layout and ``manage.py``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.4 ships with an updated default project layout and ``manage.py`` filefor the :djadmin:`startproject` management command. These fix some issues withthe previous ``manage.py`` handling of Python import paths that caused doubleimports, trouble moving from development to deployment, and otherdifficult-to-debug path issues.

The previous ``manage.py`` called functions that are now deprecated, and thusprojects upgrading to Django 1.4 should update their ``manage.py``. (Theold-style ``manage.py`` will continue to work as before until Django 1.6; in1.5 it will raise ``DeprecationWarning``).

The new recommended ``manage.py`` file should look like this::

#!/usr/bin/env python import os, sys

if __name__ == "__main__": os.environ.setdefault("DJANGO_SETTINGS_MODULE", "{{ project_name }}.settings")

from django.core.management import execute_from_command_line

execute_from_command_line(sys.argv)

``{{ project_name }}`` should be replaced with the Python package name of theactual project.

If settings, URLconfs, and apps within the project are imported or referencedusing the project name prefix (e.g. ``myproject.settings``, ``ROOT_URLCONF ="myproject.urls"``, etc), the new ``manage.py`` will need to be moved onedirectory up, so it is outside the project package rather than adjacent to``settings.py`` and ``urls.py``.

For instance, with the following layout::

manage.py mysite/ __init__.py settings.py urls.py myapp/ __init__.py models.py

You could import ``mysite.settings``, ``mysite.urls``, and ``mysite.myapp``,but not ``settings``, ``urls``, or ``myapp`` as top-level modules.

Anything imported as a top-level module can be placed adjacent to the new``manage.py``. For instance, to decouple "myapp" from the project module andimport it as just ``myapp``, place it outside the ``mysite/`` directory::

manage.py myapp/ __init__.py models.py mysite/ __init__.py settings.py urls.py

If the same code is imported inconsistently (some places with the projectprefix, some places without it), the imports will need to be cleaned up whenswitching to the new ``manage.py``.

Improved WSGI support~~~~~~~~~~~~~~~~~~~~~

The :djadmin:`startproject` management command now adds a :file:`wsgi.py`module to the initial project layout, containing a simple WSGI application thatcan be used for :doc:`deploying with WSGI appservers</howto/deployment/wsgi/index>`.

The :djadmin:`built-in development server<runserver>` now supports using anexternally-defined WSGI callable, so as to make it possible to run runserverwith the same WSGI configuration that is used for deployment. A new:setting:`WSGI_APPLICATION` setting is available to configure which WSGIcallable :djadmin:`runserver` uses.

(The :djadmin:`runfcgi` management command also internally wraps the WSGIcallable configured via :setting:`WSGI_APPLICATION`.)

Custom project and app templates~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :djadmin:`startapp` and :djadmin:`startproject` management commandsgot a ``--template`` option for specifying a path or URL to a custom app orproject template.

For example, Django will use the ``/path/to/my_project_template`` directorywhen running the following command::

django-admin.py startproject --template=/path/to/my_project_template myproject

You can also now provide a destination directory as the secondargument to both :djadmin:`startapp` and :djadmin:`startproject`::

django-admin.py startapp myapp /path/to/new/app django-admin.py startproject myproject /path/to/new/project

For more information, see the :djadmin:`startapp` and :djadmin:`startproject`documentation.

Support for time zones~~~~~~~~~~~~~~~~~~~~~~

Django 1.4 adds :ref:`support for time zones <time-zones>`. When it's enabled,Django stores date and time information in UTC in the database, uses timezone-aware datetime objects internally, and translates them to the end user'stime zone in templates and forms.

Reasons for using this feature include:

- Customizing date and time display for users around the world.- Storing datetimes in UTC for database portability and interoperability. (This argument doesn't apply to PostgreSQL, because it already stores timestamps with time zone information in Django 1.3.)- Avoiding data corruption problems around DST transitions.

Time zone support is enabled by default in new projects created with:djadmin:`startproject`. If you want to use this feature in an existingproject, there is a :ref:`migration guide <time-zones-migration-guide>`.

Minor features~~~~~~~~~~~~~~

Django 1.4 also includes several smaller improvements worth noting:

* A more usable stacktrace in the technical 500 page: frames in the stack trace which reference Django's code are dimmed out, while frames in user code are slightly emphasized. This change makes it easier to scan a stacktrace for issues in user code.

* :doc:`Tablespace support </topics/db/tablespaces>` in PostgreSQL.

* Customizable names for :meth:`~django.template.Library.simple_tag`.

* In the documentation, a helpful :doc:`security overview </topics/security>` page.

* The ``django.contrib.auth.models.check_password`` function has been moved to the ``django.contrib.auth.utils`` module. Importing it from the old location will still work, but you should update your imports.

* The :djadmin:`collectstatic` management command gained a ``--clear`` option to delete all files at the destination before copying or linking the static files.

* It is now possible to load fixtures containing forward references when using MySQL with the InnoDB database engine.

* A new 403 response handler has been added as ``'django.views.defaults.permission_denied'``. You can set your own handler by setting the value of :data:`django.conf.urls.handler403`. See the documentation about :ref:`the 403 (HTTP Forbidden) view<http_forbidden_view>` for more information.

* The :ttag:`trans` template tag now takes an optional ``as`` argument to be able to retrieve a translation string without displaying it but setting a template context variable instead.

* The :ttag:`if` template tag now supports ``{% elif %}`` clauses.

* A new plain text version of the HTTP 500 status code internal error page served when :setting:`DEBUG` is ``True`` is now sent to the client when Django detects that the request has originated in JavaScript code (:meth:`~django.http.HttpRequest.is_ajax` is used for this).

Similarly to its HTML counterpart, it contains a collection of different pieces of information about the state of the web application.

This should make it easier to read when debugging interaction with client-side Javascript code.

* Added the :djadminopt:`--no-location` option to the :djadmin:`makemessages` command.

* Changed the ``locmem`` cache backend to use ``pickle.HIGHEST_PROTOCOL`` for better compatibility with the other cache backends.

* Added support in the ORM for generating ``SELECT`` queries containing ``DISTINCT ON``.

The ``distinct()`` ``QuerySet`` method now accepts an optional list of model field names. If specified, then the ``DISTINCT`` statement is limited to these fields. This is only supported in PostgreSQL.

For more details, see the documentation for :meth:`~django.db.models.query.QuerySet.distinct`.

Backwards incompatible changes in 1.4=====================================

django.contrib.admin~~~~~~~~~~~~~~~~~~~~

The included administration app ``django.contrib.admin`` has for a long timeshipped with a default set of static files such as JavaScript, images andstylesheets. Django 1.3 added a new contrib app ``django.contrib.staticfiles``to handle such files in a generic way and defined conventions for staticfiles included in apps.

Starting in Django 1.4 the admin's static files also follow thisconvention to make it easier to deploy the included files. In previousversions of Django, it was also common to define an ``ADMIN_MEDIA_PREFIX``setting to point to the URL where the admin's static files are served by aweb server. This setting has now been deprecated and replaced by the moregeneral setting :setting:`STATIC_URL`. Django will now expect to find theadmin static files under the URL ``<STATIC_URL>/admin/``.

If you've previously used a URL path for ``ADMIN_MEDIA_PREFIX`` (e.g.``/media/``) simply make sure :setting:`STATIC_URL` and :setting:`STATIC_ROOT`are configured and your web server serves the files correctly. The developmentserver continues to serve the admin files just like before. Don't hesitate toconsult the :doc:`static files howto </howto/static-files>` for furtherdetails.

In case your ``ADMIN_MEDIA_PREFIX`` is set to an specific domain (e.g.``http://media.example.com/admin/``) make sure to also set your:setting:`STATIC_URL` setting to the correct URL, for example``http://media.example.com/``.

.. warning::

If you're implicitly relying on the path of the admin static files on your server's file system when you deploy your site, you have to update that path. The files were moved from :file:`django/contrib/admin/media/` to :file:`django/contrib/admin/static/admin/`.

Supported browsers for the admin~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django hasn't had a clear policy on which browsers are supported for using theadmin app. Django's new policy formalizes existing practices: `YUI's A-grade`_browsers should provide a fully-functional admin experience, with the notableexception of IE6, which is no longer supported.

Released over ten years ago, IE6 imposes many limitations on modern webdevelopment. The practical implications of this policy are that contributorsare free to improve the admin without consideration for these limitations.

This new policy **has no impact** on development outside of the admin. Users ofDjango are free to develop webapps compatible with any range of browsers.

.. _YUI's A-grade: http://yuilibrary.com/yui/docs/tutorials/gbs/

Removed admin icons~~~~~~~~~~~~~~~~~~~

As part of an effort to improve the performance and usability of the admin'schangelist sorting interface and of the admin's :attr:`horizontal<django.contrib.admin.ModelAdmin.filter_horizontal>` and :attr:`vertical<django.contrib.admin.ModelAdmin.filter_vertical>` "filter" widgets, some iconfiles were removed and grouped into two sprite files.

Specifically: ``selector-add.gif``, ``selector-addall.gif``,``selector-remove.gif``, ``selector-removeall.gif``,``selector_stacked-add.gif`` and ``selector_stacked-remove.gif`` werecombined into ``selector-icons.gif``; and ``arrow-up.gif`` and``arrow-down.gif`` were combined into ``sorting-icons.gif``.

If you used those icons to customize the admin then you will want to replacethem with your own icons or retrieve them from a previous release.

CSS class names in admin forms~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To avoid conflicts with other common CSS class names (e.g. "button"), a prefix"field-" has been added to all CSS class names automatically generated from theform field names in the main admin forms, stacked inline forms and tabularinline cells. You will need to take that prefix into account in your customstyle sheets or javascript files if you previously used plain field names asselectors for custom styles or javascript transformations.

Compatibility with old signed data~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.3 changed the cryptographic signing mechanisms used in a number ofplaces in Django. While Django 1.3 kept fallbacks that would accept hashesproduced by the previous methods, these fallbacks are removed in Django 1.4.

So, if you upgrade to Django 1.4 directly from 1.2 or earlier, you maylose/invalidate certain pieces of data that have been cryptographically signedusing an old method. To avoid this, use Django 1.3 first for a period of timeto allow the signed data to expire naturally. The affected parts are detailedbelow, with 1) the consequences of ignoring this advice and 2) the amount oftime you need to run Django 1.3 for the data to expire or become irrelevant.

* ``contrib.sessions`` data integrity check

* consequences: the user will be logged out, and session data will be lost.

* time period: defined by :setting:`SESSION_COOKIE_AGE`.

* ``contrib.auth`` password reset hash

* consequences: password reset links from before the upgrade will not work.

* time period: defined by :setting:`PASSWORD_RESET_TIMEOUT_DAYS`.

Form-related hashes � these are much shorter lifetime, and are relevant only forthe short window where a user might fill in a form generated by the pre-upgradeDjango instance, and try to submit it to the upgraded Django instance:

* ``contrib.comments`` form security hash

* consequences: the user will see a validation error "Security hash failed".

* time period: the amount of time you expect users to take filling out comment forms.

* ``FormWizard`` security hash

* consequences: the user will see an error about the form having expired, and will be sent back to the first page of the wizard, losing the data they have entered so far.

* time period: the amount of time you expect users to take filling out the affected forms.

* CSRF check

* Note: This is actually a Django 1.1 fallback, not Django 1.2, and applies only if you are upgrading from 1.1.

* consequences: the user will see a 403 error with any CSRF protected POST form.

* time period: the amount of time you expect user to take filling out such forms.

django.contrib.flatpages~~~~~~~~~~~~~~~~~~~~~~~~

Starting in the 1.4 release the:class:`~django.contrib.flatpages.middleware.FlatpageFallbackMiddleware` onlyadds a trailing slash and redirects if the resulting URL refers to an existingflatpage. For example, requesting ``/notaflatpageoravalidurl`` in a previousversion would redirect to ``/notaflatpageoravalidurl/``, which wouldsubsequently raise a 404. Requesting ``/notaflatpageoravalidurl`` now willimmediately raise a 404. Additionally redirects returned by flatpages are nowpermanent (301 status code) to match the behavior of the:class:`~django.middleware.common.CommonMiddleware`.

Serialization of :class:`~datetime.datetime` and :class:`~datetime.time`~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

As a consequence of time zone support, and according to the ECMA-262specification, some changes were made to the JSON serializer:

- It includes the time zone for aware datetime objects. It raises an exception for aware time objects.- It includes milliseconds for datetime and time objects. There is still some precision loss, because Python stores microseconds (6 digits) and JSON only supports milliseconds (3 digits). However, it's better than discarding microseconds entirely.

The XML serializer was also changed to use the ISO8601 format for datetimes.The letter ``T`` is used to separate the date part from the time part, insteadof a space. Time zone information is included in the ``[+-]HH:MM`` format.

The serializers will dump datetimes in fixtures with these new formats. Theycan still load fixtures that use the old format.

``supports_timezone`` changed to ``False`` for SQLite~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The database feature ``supports_timezone`` used to be ``True`` for SQLite.Indeed, if you saved an aware datetime object, SQLite stored a string thatincluded an UTC offset. However, this offset was ignored when loading the valueback from the database, which could corrupt the data.

In the context of time zone support, this flag was changed to ``False``, anddatetimes are now stored without time zone information in SQLite. When:setting:`USE_TZ` is ``False``, if you attempt to save an aware datetimeobject, Django raises an exception.

Database connection's thread-locality~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``DatabaseWrapper`` objects (i.e. the connection objects referenced by``django.db.connection`` and ``django.db.connections["some_alias"]``) used tobe thread-local. They are now global objects in order to be potentially sharedbetween multiple threads. While the individual connection objects are nowglobal, the ``django.db.connections`` dictionary referencing those objects isstill thread-local. Therefore if you just use the ORM or``DatabaseWrapper.cursor()`` then the behavior is still the same as before.Note, however, that ``django.db.connection`` does not directly reference thedefault ``DatabaseWrapper`` object anymore and is now a proxy to access thatobject's attributes. If you need to access the actual ``DatabaseWrapper``object, use ``django.db.connections[DEFAULT_DB_ALIAS]`` instead.

As part of this change, all underlying SQLite connections are now enabled forpotential thread-sharing (by passing the ``check_same_thread=False`` attributeto pysqlite). ``DatabaseWrapper`` however preserves the previous behavior bydisabling thread-sharing by default, so this does not affect any existingcode that purely relies on the ORM or on ``DatabaseWrapper.cursor()``.

Finally, while it is now possible to pass connections between threads, Djangodoes not make any effort to synchronize access to the underlying backend.Concurrency behavior is defined by the underlying backend implementation.Check their documentation for details.

`COMMENTS_BANNED_USERS_GROUP` setting~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django's :doc:`comments app </ref/contrib/comments/index>` has historicallysupported excluding the comments of a special user group, but we've neverdocumented the feature properly and didn't enforce the exclusion in other parts

of the app such as the template tags. To fix this problem, we removed the codefrom the feed class.

If you rely on the feature and want to restore the old behavior, simply usea custom comment model manager to exclude the user group, like this::

from django.conf import settings from django.contrib.comments.managers import CommentManager

class BanningCommentManager(CommentManager): def get_query_set(self): qs = super(BanningCommentManager, self).get_query_set() if getattr(settings, 'COMMENTS_BANNED_USERS_GROUP', None): where = ['user_id NOT IN (SELECT user_id FROM auth_user_groups WHERE group_id = %s)'] params = [settings.COMMENTS_BANNED_USERS_GROUP] qs = qs.extra(where=where, params=params) return qs

Save this model manager in your custom comment app (e.g. in``my_comments_app/managers.py``) and add it your:ref:`custom comment app model <custom-comment-app-api>`::

from django.db import models from django.contrib.comments.models import Comment

from my_comments_app.managers import BanningCommentManager

class CommentWithTitle(Comment): title = models.CharField(max_length=300)

objects = BanningCommentManager()

For more details, see the documentation about:doc:`customizing the comments framework </ref/contrib/comments/custom>`.

`IGNORABLE_404_STARTS` and `IGNORABLE_404_ENDS` settings~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Until Django 1.3, it was possible to exclude some URLs from Django's:doc:`404 error reporting</howto/error-reporting>` by adding prefixes to:setting:`IGNORABLE_404_STARTS` and suffixes to :setting:`IGNORABLE_404_ENDS`.

In Django 1.4, these two settings are superseded by:setting:`IGNORABLE_404_URLS`, which is a list of compiled regular expressions.Django won't send an email for 404 errors on URLs that match any of them.

Furthermore, the previous settings had some rather arbitrary default values::

IGNORABLE_404_STARTS = ('/cgi-bin/', '/_vti_bin', '/_vti_inf') IGNORABLE_404_ENDS = ('mail.pl', 'mailform.pl', 'mail.cgi', 'mailform.cgi', 'favicon.ico', '.php')

It's not Django's role to decide if your website has a legacy ``/cgi-bin/``section or a ``favicon.ico``. As a consequence, the default values of:setting:`IGNORABLE_404_URLS`, :setting:`IGNORABLE_404_STARTS` and:setting:`IGNORABLE_404_ENDS` are all now empty.

If you have customized :setting:`IGNORABLE_404_STARTS` or:setting:`IGNORABLE_404_ENDS`, or if you want to keep the old default value,

you should add the following lines in your settings file::

import re IGNORABLE_404_URLS = ( # for each <prefix> in IGNORABLE_404_STARTS re.compile(r'^<prefix>'), # for each <suffix> in IGNORABLE_404_ENDS re.compile(r'<suffix>$'), )

Don't forget to escape characters that have a special meaning in a regularexpression.

CSRF protection extended to PUT and DELETE~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Previously, Django's :doc:`CSRF protection </ref/contrib/csrf/>` providedprotection against only POST requests. Since use of PUT and DELETE methods inAJAX applications is becoming more common, we now protect all methods notdefined as safe by :rfc:`2616` i.e. we exempt GET, HEAD, OPTIONS and TRACE, andenforce protection on everything else.

If you are using PUT or DELETE methods in AJAX applications, please see the:ref:`instructions about using AJAX and CSRF <csrf-ajax>`.

``django.core.template_loaders``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This was an alias to ``django.template.loader`` since 2005, it has been removedwithout emitting a warning due to the length of the deprecation. If your codestill referenced this please use ``django.template.loader`` instead.

``django.db.models.fields.URLField.verify_exists``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This functionality has been removed due to intractable performance andsecurity issues. Any existing usage of ``verify_exists`` should beremoved.

``django.core.files.storage.Storage.open``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``open`` method of the base Storage class took an obscure parameter``mixin`` which allowed you to dynamically change the base classes of thereturned file object. This has been removed. In the rare case you relied on the`mixin` parameter, you can easily achieve the same by overriding the `open`method, e.g.::

from django.core.files import File from django.core.files.storage import FileSystemStorage

class Spam(File): """ Spam, spam, spam, spam and spam. """ def ham(self): return 'eggs'

class SpamStorage(FileSystemStorage): """

A custom file storage backend. """ def open(self, name, mode='rb'): return Spam(open(self.path(name), mode))

YAML deserializer now uses ``yaml.safe_load``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``yaml.load`` is able to construct any Python object, which may triggerarbitrary code execution if you process a YAML document that comes from anuntrusted source. This feature isn't necessary for Django's YAML deserializer,whose primary use is to load fixtures consisting of simple objects. Even thoughfixtures are trusted data, for additional security, the YAML deserializer nowuses ``yaml.safe_load``.

Features deprecated in 1.4==========================

Old styles of calling ``cache_page`` decorator~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Some legacy ways of calling :func:`~django.views.decorators.cache.cache_page`have been deprecated, please see the docs for the correct way to use thisdecorator.

Support for PostgreSQL versions older than 8.2~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.3 dropped support for PostgreSQL versions older than 8.0 and therelevant documents suggested to use a recent version because of performancereasons but more importantly because end of the upstream support periods forreleases 8.0 and 8.1 was near (November 2010).

Django 1.4 takes that policy further and sets 8.2 as the minimum PostgreSQLversion it officially supports.

Request exceptions are now always logged~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When :doc:`logging support </topics/logging/>` was added to Django in 1.3, theadmin error email support was moved into the:class:`django.utils.log.AdminEmailHandler`, attached to the``'django.request'`` logger. In order to maintain the established behavior oferror emails, the ``'django.request'`` logger was called only when:setting:`DEBUG` was ``False``.

To increase the flexibility of error logging for requests, the``'django.request'`` logger is now called regardless of the value of:setting:`DEBUG`, and the default settings file for new projects now includes aseparate filter attached to :class:`django.utils.log.AdminEmailHandler` toprevent admin error emails in ``DEBUG`` mode::

'filters': { 'require_debug_false': { '()': 'django.utils.log.RequireDebugFalse' } }, 'handlers': { 'mail_admins': { 'level': 'ERROR',

'filters': ['require_debug_false'], 'class': 'django.utils.log.AdminEmailHandler' } },

If your project was created prior to this change, your :setting:`LOGGING`setting will not include this new filter. In order to maintainbackwards-compatibility, Django will detect that your ``'mail_admins'`` handlerconfiguration includes no ``'filters'`` section, and will automatically addthis filter for you and issue a pending-deprecation warning. This will become adeprecation warning in Django 1.5, and in Django 1.6 thebackwards-compatibility shim will be removed entirely.

The existence of any ``'filters'`` key under the ``'mail_admins'`` handler willdisable this backward-compatibility shim and deprecation warning.

``django.conf.urls.defaults``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Until Django 1.3 the functions :func:`~django.conf.urls.include`,:func:`~django.conf.urls.patterns` and :func:`~django.conf.urls.url` plus:data:`~django.conf.urls.handler404`, :data:`~django.conf.urls.handler500`were located in a ``django.conf.urls.defaults`` module.

Starting with Django 1.4 they are now available in :mod:`django.conf.urls`.

``django.contrib.databrowse``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Databrowse has not seen active development for some time, and this does not showany sign of changing. There had been a suggestion for a `GSOC project`_ tointegrate the functionality of databrowse into the admin, but no progress wasmade. While Databrowse has been deprecated, an enhancement of``django.contrib.admin`` providing a similar feature set is still possible.

.. _GSOC project: https://code.djangoproject.com/wiki/SummerOfCode2011#Integratedatabrowseintotheadmin

The code that powers Databrowse is licensed under the same terms as Djangoitself, and so is available to be adopted by an individual or group asa third-party project.

``django.core.management.setup_environ``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This function temporarily modified ``sys.path`` in order to make the parent"project" directory importable under the old flat :djadmin:`startproject`layout. This function is now deprecated, as its path workarounds are no longerneeded with the new ``manage.py`` and default project layout.

This function was never documented or part of the public API, but was widelyrecommended for use in setting up a "Django environment" for a user script.These uses should be replaced by setting the ``DJANGO_SETTINGS_MODULE``environment variable or using :func:`django.conf.settings.configure`.

``django.core.management.execute_manager``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This function was previously used by ``manage.py`` to execute a managementcommand. It is identical to

``django.core.management.execute_from_command_line``, except that it firstcalls ``setup_environ``, which is now deprecated. As such, ``execute_manager``is also deprecated; ``execute_from_command_line`` can be used instead. Neitherof these functions is documented as part of the public API, but a deprecationpath is needed due to use in existing ``manage.py`` files.

``is_safe`` and ``needs_autoescape`` attributes of template filters~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Two flags, ``is_safe`` and ``needs_autoescape``, define how each template filterinteracts with Django's auto-escaping behavior. They used to be attributes ofthe filter function::

@register.filter def noop(value): return value noop.is_safe = True

However, this technique caused some problems in combination with decorators,especially :func:`@stringfilter <django.template.defaultfilters.stringfilter>`.Now, the flags are keyword arguments of :meth:`@register.filter<django.template.Library.filter>`::

@register.filter(is_safe=True) def noop(value): return value

See :ref:`filters and auto-escaping <filters-auto-escaping>` for more information.

Session cookies now have the ``httponly`` flag by default~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Session cookies now include the ``httponly`` attribute by default tohelp reduce the impact of potential XSS attacks. For strict backwardscompatibility, use ``SESSION_COOKIE_HTTPONLY = False`` in your settings file.

Wildcard expansion of application names in `INSTALLED_APPS`~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Until Django 1.3, :setting:`INSTALLED_APPS` accepted wildcards in applicationnames, like ``django.contrib.*``. The expansion was performed by afilesystem-based implementation of ``from <package> import *``. Unfortunately,`this can't be done reliably`_.

This behavior was never documented. Since it is un-pythonic and not obviouslyuseful, it was removed in Django 1.4. If you relied on it, you must edit yoursettings file to list all your applications explicitly.

.. _this can't be done reliably: http://docs.python.org/tutorial/modules.html#importing-from-a-package

``HttpRequest.raw_post_data`` renamed to ``HttpRequest.body``~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This attribute was confusingly named ``HttpRequest.raw_post_data``, but itactually provided the body of the HTTP request. It's been renamed to``HttpRequest.body``, and ``HttpRequest.raw_post_data`` has been deprecated.

The Django 1.4 roadmap

======================

Before the final Django 1.4 release, several other preview/development releaseswill be made available. The current schedule consists of at least the following:

* Week of **January 30, 2012**: First Django 1.4 beta release; final feature freeze for Django 1.4.

* Week of **February 27, 2012**: First Django 1.4 release candidate; string freeze for translations.

* Week of **March 5, 2012**: Django 1.4 final release.

If necessary, additional alpha, beta or release-candidate packageswill be issued prior to the final 1.4 release. Django 1.4 will bereleased approximately one week after the final release candidate.

What you can do to help=======================

In order to provide a high-quality 1.4 release, we need your help. Although thisalpha release is, again, *not* intended for production use, you can help theDjango team by trying out the alpha codebase in a safe test environment andreporting any bugs or issues you encounter. The Django ticket tracker is thecentral place to search for open issues:

* https://code.djangoproject.com/timeline

Please open new tickets if no existing ticket corresponds to a problem you'rerunning into.

Additionally, discussion of Django development, including progress toward the1.3 release, takes place daily on the django-developers mailing list:

* http://groups.google.com/group/django-developers

... and in the ``#django-dev`` IRC channel on ``irc.freenode.net``. If you'reinterested in helping out with Django's development, feel free to join thediscussions there.

Django's online documentation also includes pointers on how to contribute toDjango:

* :doc:`How to contribute to Django </internals/contributing/index>`

Contributions on any level -- developing code, writing documentation or simplytriaging tickets and helping to test proposed bugfixes -- are always welcome andappreciated.

Several development sprints will also be taking place before the 1.4release; these will typically be announced in advance on thedjango-developers mailing list, and anyone who wants to help iswelcome to join in.