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

Django 1.4 release notes

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

*March 23, 2012*

Welcome to Django 1.4!

These release notes cover the :ref:`new features <whats-new-1.4>`, as well as

some :ref:`backwards incompatible changes <backwards-incompatible-1.4>` you'll

want to be aware of when upgrading from Django 1.3 or older versions. We've

also dropped some features, which are detailed in :ref:`our deprecation plan

<deprecation-removed-in-1.4>`, and we've :ref:`begun the deprecation process

for some features <deprecated-features-1.4>`.

Overview

========

The biggest new feature in Django 1.4 is `support for time zones`_ when

handling date/times. When enabled, this Django will store date/times in UTC,

use timezone-aware objects internally, and translate them to users' local

timezones for display.

If you're upgrading an existing project to Django 1.4, switching to the timezone

aware mode may take some care: the new mode disallows some rather sloppy

behavior that used to be accepted. We encourage anyone who's upgrading to check

out the :ref:`timezone migration guide <time-zones-migration-guide>` and the

:ref:`timezone FAQ <time-zones-faq>` for useful pointers.

Other notable new features in Django 1.4 include:

* A number of ORM improvements, including `SELECT FOR UPDATE support`_,

the ability to `bulk insert <#model-objects-bulk-create-in-the-orm>`_

large datasets for improved performance, and

`QuerySet.prefetch_related`_, a method to batch-load related objects

in areas where :meth:`~django.db.models.query.QuerySet.select_related`

doesn't work.

* Some nice security additions, including `improved password hashing`_

(featuring PBKDF2_ and bcrypt_ support), new `tools for cryptographic

signing`_, several `CSRF improvements`_, and `simple clickjacking

protection`_.

* An `updated default project layout and manage.py`_ that removes the "magic"

from prior versions. And for those who don't like the new layout, you can

use `custom project and app templates`_ instead!

* `Support for in-browser testing frameworks`_ (like Selenium_).

* ... and a whole lot more; `see below <#what-s-new-in-django-1-4>`_!

Wherever possible we try to introduce new features in a backwards-compatible

manner per :doc:`our API stability policy </misc/api-stability>` policy.

However, as with previous releases, Django 1.4 ships with some minor

:ref:`backwards incompatible changes <backwards-incompatible-1.4>`; people

upgrading from previous versions of Django should read that list carefully.

Python compatibility

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

Django 1.4 has dropped support for Python 2.4. Python 2.5 is now the minimum

required Python version. 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 most

operating-system vendors today are shipping Python 2.5 or newer as their default

version. If you're still using Python 2.4, however, you'll need to stick to

Django 1.3 until you can upgrade. Per :doc:`our support policy

</internals/release-process>`, Django 1.3 will continue to receive security

support until the release of Django 1.5.

Django does not support Python 3.x at this time. At some point before the

release of Django 1.4, we plan to publish a document outlining our full

timeline for deprecating Python 2.x and moving to Python 3.x.

.. _whats-new-1.4:

What's new in Django 1.4

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

Support for time zones

----------------------

In previous versions, Django used "naive" date/times (that is, date/times

without an associated time zone), leaving it up to each developer to interpret

what a given date/time "really means". This can cause all sorts of subtle

timezone-related bugs.

In Django 1.4, you can now switch Django into a more correct, time-zone aware

mode. In this mode, Django stores date and time information in UTC in the

database, uses time-zone-aware datetime objects internally and translates them

to the end user's time 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 existing

project, read the :ref:`migration guide <time-zones-migration-guide>`. If you

encounter problems, there's a helpful :ref:`FAQ <time-zones-faq>`.

Support for in-browser testing frameworks

-----------------------------------------

Django 1.4 supports integration with in-browser testing frameworks like

Selenium_. The new :class:`django.test.LiveServerTestCase` base class lets you

test the interactions between your site's front and back ends more

comprehensively. See the

:class:`documentation<django.test.LiveServerTestCase>` for more details and

concrete examples.

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

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

------------------------------------------------

Django 1.4 ships with an updated default project layout and ``manage.py`` file

for the :djadmin:`startproject` management command. These fix some issues with

the previous ``manage.py`` handling of Python import paths that caused double

imports, trouble moving from development to deployment, and other

difficult-to-debug path issues.

The previous ``manage.py`` called functions that are now deprecated, and thus

projects upgrading to Django 1.4 should update their ``manage.py``. (The

old-style ``manage.py`` will continue to work as before until Django 1.6. In

1.5 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 the

actual project.

If settings, URLconfs and apps within the project are imported or referenced

using the project name prefix (e.g. ``myproject.settings``, ``ROOT_URLCONF =

"myproject.urls"``, etc.), the new ``manage.py`` will need to be moved one

directory 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 and

import 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 project

prefix, some places without it), the imports will need to be cleaned up when

switching to the new ``manage.py``.

Custom project and app templates

--------------------------------

The :djadmin:`startapp` and :djadmin:`startproject` management commands

now have a ``--template`` option for specifying a path or URL to a custom app

or project template.

For example, Django will use the ``/path/to/my_project_template`` directory

when you run the following command::

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

You can also now provide a destination directory as the second

argument 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.

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 that

can be used for :doc:`deploying with WSGI app

servers</howto/deployment/wsgi/index>`.

The :djadmin:`built-in development server<runserver>` now supports using an

externally-defined WSGI callable, which makes it possible to run runserver

with the same WSGI configuration that is used for deployment. The new

:setting:`WSGI_APPLICATION` setting lets you configure which WSGI callable

:djadmin:`runserver` uses.

(The ``runfcgi`` management command also internally wraps the WSGI

callable configured via :setting:`WSGI_APPLICATION`.)

``SELECT FOR UPDATE`` support

-----------------------------

Django 1.4 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 the

transaction, meaning other transactions cannot modify or delete rows matched 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 lets you create multiple objects more efficiently. It can result in

significant performance increases if you have many objects.

Django makes use of this internally, meaning some operations (such as database

setup for test suites) have seen a performance benefit as a result.

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

information.

``QuerySet.prefetch_related``

-----------------------------

Similar to :meth:`~django.db.models.query.QuerySet.select_related` but with a

different 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 a

single batch as soon as the query begins to be evaluated. Unlike

``select_related``, it does the joins in Python, not in the database, and

supports many-to-many relationships, ``GenericForeignKey`` and more. This

allows you to fix a very common performance problem in which your code ends up

doing O(n) database queries (or worse) if objects on your primary ``QuerySet``

each have many related objects that you also need to fetch.

Improved password hashing

-------------------------

Django's auth system (``django.contrib.auth``) stores passwords using a one-way

algorithm. Django 1.3 uses the SHA1_ algorithm, but increasing processor speeds

and 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 now

uses the PBKDF2_ algorithm (as recommended by NIST_). You can also easily choose

a different algorithm (including the popular bcrypt_ algorithm). For more

details, see :ref:`auth_password_storage`.

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

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

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

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

HTML5 doctype

-------------

We've switched the admin and other bundled templates to use the HTML5

doctype. While Django will be careful to maintain compatibility with older

browsers, this change means that you can use any HTML5 features you need in

admin pages without having to lose HTML validity or override the provided

templates to change the doctype.

List filters in admin interface

-------------------------------

Prior to Django 1.4, the :mod:`~django.contrib.admin` app let you specify

change list filters by specifying a field lookup, but it didn't allow you to

create custom filters. This has been rectified with a simple API (previously

used internally and known as "FilterSpec"). For more details, see the

documentation for :attr:`~django.contrib.admin.ModelAdmin.list_filter`.

Multiple sort in admin interface

--------------------------------

The admin change list now supports sorting on multiple columns. It respects all

elements of the :attr:`~django.contrib.admin.ModelAdmin.ordering` attribute, and

sorting on multiple columns by clicking on headers is designed to mimic the

behavior of desktop GUIs. We also added a

:meth:`~django.contrib.admin.ModelAdmin.get_ordering` method for specifying the

ordering dynamically (i.e., depending on the request).

New ``ModelAdmin`` methods

--------------------------

We added a :meth:`~django.contrib.admin.ModelAdmin.save_related` method to

:mod:`~django.contrib.admin.ModelAdmin` to ease customization of how

related objects are saved in the admin.

Two other new :class:`~django.contrib.admin.ModelAdmin` methods,

:meth:`~django.contrib.admin.ModelAdmin.get_list_display` and

:meth:`~django.contrib.admin.ModelAdmin.get_list_display_links`

enable dynamic customization of fields and links displayed on the admin

change list.

Admin inlines respect user permissions

--------------------------------------

Admin inlines now only allow those actions for which the user has

permission. For ``ManyToMany`` relationships with an auto-created intermediate

model (which does not have its own permissions), the change permission for the

related model determines if the user has the permission to add, change or

delete relationships.

Tools for cryptographic signing

-------------------------------

Django 1.4 adds both a low-level API for signing values and a high-level API

for setting and reading signed cookies, one of the most common uses of

signing in Web applications.

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

information.

Cookie-based session backend

----------------------------

Django 1.4 introduces a cookie-based session backend that uses the tools for

:doc:`cryptographic signing </topics/signing>` to store the session data in

the client's browser.

.. warning::

Session data is signed and validated by the server, but it's not

encrypted. This means a user can view any data stored in the

session but cannot change it. Please read the documentation for

further clarification before using this backend.

See the :ref:`cookie-based session backend <cookie-session-backend>` docs for

more information.

New form wizard

---------------

The previous ``FormWizard`` from ``django.contrib.formtools`` has been

replaced with a new implementation based on the class-based views

introduced in Django 1.3. It features a pluggable storage API and doesn't

require the wizard to pass around hidden fields for every previous step.

Django 1.4 ships with a session-based storage backend and a cookie-based

storage backend. The latter uses the tools for

:doc:`cryptographic signing </topics/signing>` also introduced in

Django 1.4 to store the wizard's state in the user's cookies.

``reverse_lazy``

----------------

A lazily evaluated version of ``reverse()`` was added to allow using URL

reversals before the project's URLconf gets loaded.

Translating URL patterns

------------------------

Django can now look for a language prefix in the URLpattern when using the new

:func:`~django.conf.urls.i18n.i18n_patterns` helper function.

It's also now possible to define translatable URL patterns using

:func:`~django.utils.translation.ugettext_lazy`. See

:ref:`url-internationalization` for more information about the language prefix

and how to internationalize URL patterns.

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

---------------------------------------------------------------------------

The :ref:`contextual translation<contextual-markers>` support introduced in

Django 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` to

enable the customization of URLconf keyword arguments used for single

object generic views.

Assignment template tags

------------------------

A new ``assignment_tag`` helper function was added to ``template.Library`` to

ease the creation of template tags 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>` and newly

introduced ``assignment_tag`` template helper functions may now accept any

number of positional or keyword arguments. For example::

@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 ``TEMPLATE_DEBUG`` setting

was ``True``, any exception raised during template rendering (even exceptions

unrelated to template syntax) were wrapped in ``TemplateSyntaxError`` and

re-raised. This was done in order to provide detailed template source location

information in the debug 500 page.

In Django 1.4, exceptions are no longer wrapped. Instead, the original

exception is annotated with the source information. This means that catching

exceptions from template rendering is now consistent regardless of the value of

``TEMPLATE_DEBUG``, and there's no need to catch and unwrap

``TemplateSyntaxError`` in order to catch other errors.

``truncatechars`` template filter

---------------------------------

This new filter truncates a string to be no longer than the specified

number of characters. Truncated strings end with a translatable ellipsis

sequence ("..."). See the documentation for :tfilter:`truncatechars` for

more details.

``static`` template tag

-----------------------

The :mod:`staticfiles<django.contrib.staticfiles>` contrib app has a new

``static`` template tag to refer to files saved with the

:setting:`STATICFILES_STORAGE` storage backend. It uses the storage backend's

``url`` method and therefore supports advanced features such as :ref:`serving

files from a cloud service<staticfiles-from-cdn>`.

``CachedStaticFilesStorage`` storage backend

--------------------------------------------

The :mod:`staticfiles<django.contrib.staticfiles>` contrib app now has a

:class:`~django.contrib.staticfiles.storage.CachedStaticFilesStorage` backend

that caches the files it saves (when running the :djadmin:`collectstatic`

management command) by appending the MD5 hash of the file's content to the

filename. 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

<https://en.wikipedia.org/wiki/Clickjacking>`_ using the ``X-Frame-Options``

header. It's not enabled by default for backwards compatibility reasons, but

you'll almost certainly want to :doc:`enable it </ref/clickjacking/>` to help

plug 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 can

help with AJAX-heavy sites; protection for PUT and DELETE requests; and the

:setting:`CSRF_COOKIE_SECURE` and :setting:`CSRF_COOKIE_PATH` settings, which can

improve the security and usefulness of CSRF protection. See the :doc:`CSRF

docs </ref/csrf>` for more information.

Error report filtering

----------------------

We added two function decorators,

:func:`~django.views.decorators.debug.sensitive_variables` and

:func:`~django.views.decorators.debug.sensitive_post_parameters`, to allow

designating the local variables and POST parameters that may contain sensitive

information and should be filtered out of error reports.

All POST parameters are now systematically filtered out of error reports for

certain 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 sensitive

information such as user passwords.

You can override or customize the default filtering by writing a :ref:`custom

filter<custom-error-reports>`. For more information see the docs on

:ref:`Filtering error reports<filtering-error-reports>`.

Extended IPv6 support

---------------------

Django 1.4 can now better handle IPv6 addresses with the new

:class:`~django.db.models.GenericIPAddressField` model field,

:class:`~django.forms.GenericIPAddressField` form field and

the validators :data:`~django.core.validators.validate_ipv46_address` and

:data:`~django.core.validators.validate_ipv6_address`.

HTML comparisons in tests

-------------------------

The base classes in :mod:`django.test` now have some helpers to

compare HTML without tripping over irrelevant differences in whitespace,

argument quoting/ordering and closing of self-closing tags. You can either

compare HTML directly with the new

:meth:`~django.test.SimpleTestCase.assertHTMLEqual` and

:meth:`~django.test.SimpleTestCase.assertHTMLNotEqual` assertions, or use

the ``html=True`` flag with

:meth:`~django.test.SimpleTestCase.assertContains` and

:meth:`~django.test.SimpleTestCase.assertNotContains` to test whether the

client's response contains a given HTML fragment. See the :ref:`assertions

documentation <assertions>` for more.

Two new date format strings

---------------------------

Two new :tfilter:`date` formats were added for use in template filters,

template tags and :doc:`/topics/i18n/formatting`:

- ``e`` -- the name of the timezone of the given datetime object

- ``o`` -- the ISO 8601 year number

Please make sure to update your :ref:`custom format files

<custom-format-files>` if they contain either ``e`` or ``o`` in a format

string. For example a Spanish localization format previously only escaped the

``d`` format character::

DATE_FORMAT = r'j \de F \de Y'

But now it needs to also escape ``e`` and ``o``::

DATE_FORMAT = r'j \d\e F \d\e Y'

For more information, see the :tfilter:`date` documentation.

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 that reference Django's framework code are dimmed out,

while frames in application code are slightly emphasized. This change

makes it easier to scan a stacktrace for issues in application 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 :mod:`django.contrib.auth.hashers` module. Importing it from the old

location will still work, but you should update your imports.

* The :djadmin:`collectstatic` management command now has a ``--clear`` option

to delete all files at the destination before copying or linking the static

files.

* It's 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 :djadmin:`makemessages` command uses a new and more accurate lexer,

`JsLex`_, for extracting translatable strings from JavaScript files.

.. _JsLex: https://bitbucket.org/ned/jslex

* 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.

* If your Django app is behind a proxy, you might find the new

:setting:`SECURE_PROXY_SSL_HEADER` setting useful. It solves the problem of your

proxy "eating" the fact that a request came in via HTTPS. But only use this

setting if you know what you're doing.

* 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.)

Like its HTML counterpart, it contains a collection of different

pieces of information about the state of the application.

This should make it easier to read when debugging interaction with

client-side JavaScript.

* Added the :option:`makemessages --no-location` option.

* 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`.

* The admin login page will add a password reset link if you include a URL with

the name `'admin_password_reset'` in your urls.py, so plugging in the built-in

password reset mechanism and making it available is now much easier. For

details, see :ref:`auth_password_reset`.

* The MySQL database backend can now make use of the savepoint feature

implemented by MySQL version 5.0.3 or newer with the InnoDB storage engine.

* It's now possible to pass initial values to the model forms that are part of

both model formsets and inline model formsets as returned from factory

functions ``modelformset_factory`` and ``inlineformset_factory`` respectively

just like with regular formsets. However, initial values only apply to extra

forms, i.e. those which are not bound to an existing model instance.

* The sitemaps framework can now handle HTTPS links using the new

:attr:`Sitemap.protocol <django.contrib.sitemaps.Sitemap.protocol>` class

attribute.

* A new :class:`django.test.SimpleTestCase` subclass of

:class:`unittest.TestCase`

that's lighter than :class:`django.test.TestCase` and company. It can be

useful in tests that don't need to hit a database. See

:ref:`testcase_hierarchy_diagram`.

.. _backwards-incompatible-1.4:

Backwards incompatible changes in 1.4

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

SECRET_KEY setting is required

------------------------------

Running Django with an empty or known :setting:`SECRET_KEY` disables many of

Django's security protections and can lead to remote-code-execution

vulnerabilities. No Django site should ever be run without a

:setting:`SECRET_KEY`.

In Django 1.4, starting Django with an empty :setting:`SECRET_KEY` will raise a

`DeprecationWarning`. In Django 1.5, it will raise an exception and Django will

refuse to start. This is slightly accelerated from the usual deprecation path

due to the severity of the consequences of running Django with no

:setting:`SECRET_KEY`.

``django.contrib.admin``

------------------------

The included administration app ``django.contrib.admin`` has for a long time

shipped with a default set of static files such as JavaScript, images and

stylesheets. Django 1.3 added a new contrib app ``django.contrib.staticfiles``

to handle such files in a generic way and defined conventions for static

files included in apps.

Starting in Django 1.4, the admin's static files also follow this

convention, to make the files easier to deploy. In previous versions of Django,

it was also common to define an ``ADMIN_MEDIA_PREFIX`` setting to point to the

URL where the admin's static files live on a Web server. This setting has now

been deprecated and replaced by the more general setting :setting:`STATIC_URL`.

Django will now expect to find the admin 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 those files correctly. The

development server continues to serve the admin files just like before. Read

the :doc:`static files howto </howto/static-files/index>` for more details.

If 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 within

Django's source code, you'll need 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 by the

admin app. Our new policy formalizes existing practices: `YUI's A-grade`_

browsers should provide a fully-functional admin experience, with the notable

exception of Internet Explorer 6, which is no longer supported.

Released over 10 years ago, IE6 imposes many limitations on modern Web

development. The practical implications of this policy are that contributors

are free to improve the admin without consideration for these limitations.

Obviously, this new policy **has no impact** on sites you develop using Django.

It only applies to the Django admin. Feel free to develop apps 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's

change-list sorting interface and :attr:`horizontal

<django.contrib.admin.ModelAdmin.filter_horizontal>` and :attr:`vertical

<django.contrib.admin.ModelAdmin.filter_vertical>` "filter" widgets, some icon

files 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`` were

combined 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'll need to replace

them with your own icons or get the files from a previous release.

CSS class names in admin forms

------------------------------

To avoid conflicts with other common CSS class names (e.g. "button"), we added

a prefix ("field-") to all CSS class names automatically generated from the

form field names in the main admin forms, stacked inline forms and tabular

inline cells. You'll need to take that prefix into account in your custom

style sheets or JavaScript files if you previously used plain field names as

selectors for custom styles or JavaScript transformations.

Compatibility with old signed data

----------------------------------

Django 1.3 changed the cryptographic signing mechanisms used in a number of

places in Django. While Django 1.3 kept fallbacks that would accept hashes

produced 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 may

lose/invalidate certain pieces of data that have been cryptographically signed

using an old method. To avoid this, use Django 1.3 first for a period of time

to allow the signed data to expire naturally. The affected parts are detailed

below, with 1) the consequences of ignoring this advice and 2) the amount of

time 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 have a are much shorter lifetime and are relevant

only for the short window where a user might fill in a form generated by the

pre-upgrade Django instance and try to submit it to the upgraded Django

instance:

* ``contrib.comments`` form security hash

* Consequences: The user will see the 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

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 it applies only if you're 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.

* ``contrib.auth`` user password hash-upgrade sequence

* Consequences: Each user's password will be updated to a stronger password

hash when it's written to the database in 1.4. This means that if you

upgrade to 1.4 and then need to downgrade to 1.3, version 1.3 won't be able

to read the updated passwords.

* Remedy: Set :setting:`PASSWORD_HASHERS` to use your original password

hashing when you initially upgrade to 1.4. After you confirm your app works

well with Django 1.4 and you won't have to roll back to 1.3, enable the new

password hashes.

``django.contrib.flatpages``

----------------------------

Starting in 1.4, the

:class:`~django.contrib.flatpages.middleware.FlatpageFallbackMiddleware` only

adds a trailing slash and redirects if the resulting URL refers to an existing

flatpage. For example, requesting ``/notaflatpageoravalidurl`` in a previous

version would redirect to ``/notaflatpageoravalidurl/``, which would

subsequently raise a 404. Requesting ``/notaflatpageoravalidurl`` now will

immediately raise a 404.

Also, redirects returned by flatpages are now permanent (with 301 status code),

to match the behavior of :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-262

specification, we made changes 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.

We changed the XML serializer to use the ISO8601 format for datetimes.

The letter ``T`` is used to separate the date part from the time part, instead

of a space. Time zone information is included in the ``[+-]HH:MM`` format.

Though the serializers now use these new formats when creating fixtures, they

can 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 that

included an UTC offset. However, this offset was ignored when loading the value

back from the database, which could corrupt the data.

In the context of time-zone support, this flag was changed to ``False``, and

datetimes are now stored without time-zone information in SQLite. When

:setting:`USE_TZ` is ``False``, if you attempt to save an aware datetime

object, Django raises an exception.

``MySQLdb``-specific exceptions

-------------------------------

The MySQL backend historically has raised ``MySQLdb.OperationalError``

when a query triggered an exception. We've fixed this bug, and we now raise

:exc:`django.db.DatabaseError` instead. If you were testing for

``MySQLdb.OperationalError``, you'll need to update your ``except``

clauses.

Database connection's thread-locality

-------------------------------------

``DatabaseWrapper`` objects (i.e. the connection objects referenced by

``django.db.connection`` and ``django.db.connections["some_alias"]``) used to

be thread-local. They are now global objects in order to be potentially shared

between multiple threads. While the individual connection objects are now

global, the ``django.db.connections`` dictionary referencing those objects is

still 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 the

default ``DatabaseWrapper`` object anymore and is now a proxy to access that

object'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 for

potential thread-sharing (by passing the ``check_same_thread=False`` attribute

to pysqlite). ``DatabaseWrapper`` however preserves the previous behavior by

disabling thread-sharing by default, so this does not affect any existing

code that purely relies on the ORM or on ``DatabaseWrapper.cursor()``.

Finally, while it's now possible to pass connections between threads, Django

doesn't 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 comments has historically

supported excluding the comments of a special user group, but we've never

documented 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 code

from the feed class.

If you rely on the feature and want to restore the old behavior, use a 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().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 custom comment app model::

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()

`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

``IGNORABLE_404_STARTS`` and suffixes to ``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`, ``IGNORABLE_404_STARTS``, and

``IGNORABLE_404_ENDS`` are all now empty.

If you have customized ``IGNORABLE_404_STARTS`` or ``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 regular

expression, such as periods.

CSRF protection extended to PUT and DELETE

------------------------------------------

Previously, Django's :doc:`CSRF protection </ref/csrf/>` provided

protection only against POST requests. Since use of PUT and DELETE methods in

AJAX applications is becoming more common, we now protect all methods not

defined as safe by :rfc:`2616` -- i.e., we exempt GET, HEAD, OPTIONS and TRACE,

and we enforce protection on everything else.

If you're using PUT or DELETE methods in AJAX applications, please see the

:ref:`instructions about using AJAX and CSRF <csrf-ajax>`.