504 lines
19 KiB
Plaintext
504 lines
19 KiB
Plaintext
.. _releases-1.2:
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============================================
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Django 1.2 release notes — UNDER DEVELOPMENT
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============================================
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This page documents release notes for the as-yet-unreleased Django 1.2. As such
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it is tentative and subject to change. It provides up-to-date information for
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those who are following trunk.
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Django 1.2 includes a number of nifty `new features`_, lots of bug
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fixes, and an easy upgrade path from Django 1.1.
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.. _new features: `What's new in Django 1.2`_
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.. _backwards-incompatible-changes-1.2:
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Backwards-incompatible changes in 1.2
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=====================================
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CSRF Protection
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---------------
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There have been large changes to the way that CSRF protection works, detailed in
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:ref:`the CSRF documentaton <ref-contrib-csrf>`. The following are the major
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changes that developers must be aware of:
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* ``CsrfResponseMiddleware`` and ``CsrfMiddleware`` have been deprecated, and
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will be removed completely in Django 1.4, in favor of a template tag that
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should be inserted into forms.
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* All contrib apps use a ``csrf_protect`` decorator to protect the view. This
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requires the use of the csrf_token template tag in the template, so if you
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have used custom templates for contrib views, you MUST READ THE :ref:`UPGRADE
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INSTRUCTIONS <ref-csrf-upgrading-notes>` to fix those templates.
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* ``CsrfViewMiddleware`` is included in :setting:`MIDDLEWARE_CLASSES` by
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default. This turns on CSRF protection by default, so that views that accept
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POST requests need to be written to work with the middleware. Instructions
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on how to do this are found in the CSRF docs.
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* All of the CSRF has moved from contrib to core (with backwards compatible
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imports in the old locations, which are deprecated).
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:ttag:`if` tag changes
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----------------------
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Due to new features in the :ttag:`if` template tag, it no longer accepts 'and',
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'or' and 'not' as valid **variable** names. Previously that worked in some
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cases even though these strings were normally treated as keywords. Now, the
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keyword status is always enforced, and template code like ``{% if not %}`` or
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``{% if and %}`` will throw a TemplateSyntaxError.
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``LazyObject``
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--------------
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``LazyObject`` is an undocumented utility class used for lazily wrapping other
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objects of unknown type. In Django 1.1 and earlier, it handled introspection in
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a non-standard way, depending on wrapped objects implementing a public method
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``get_all_members()``. Since this could easily lead to name clashes, it has been
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changed to use the standard method, involving ``__members__`` and ``__dir__()``.
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If you used ``LazyObject`` in your own code, and implemented the
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``get_all_members()`` method for wrapped objects, you need to make the following
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changes:
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* If your class does not have special requirements for introspection (i.e. you
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have not implemented ``__getattr__()`` or other methods that allow for
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attributes not discoverable by normal mechanisms), you can simply remove the
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``get_all_members()`` method. The default implementation on ``LazyObject``
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will do the right thing.
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* If you have more complex requirements for introspection, first rename the
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``get_all_members()`` method to ``__dir__()``. This is the standard method,
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from Python 2.6 onwards, for supporting introspection. If you are require
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support for Python < 2.6, add the following code to the class::
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__members__ = property(lambda self: self.__dir__())
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Specifying databases
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--------------------
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Prior to Django 1.1, Django used a number of settings to control access to a
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single database. Django 1.2 introduces support for multiple databases, and as
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a result, the way you define database settings has changed.
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Any existing Django settings file will continue to work as expected until
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Django 1.4. Old-style database settings will be automatically translated to
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the new-style format.
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In the old-style (pre 1.2) format, there were a number of
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``DATABASE_`` settings at the top level of your settings file. For
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example::
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DATABASE_NAME = 'test_db'
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DATABASE_BACKEND = 'postgresl_psycopg2'
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DATABASE_USER = 'myusername'
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DATABASE_PASSWORD = 's3krit'
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These settings are now contained inside a dictionary named
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:setting:`DATABASES`. Each item in the dictionary corresponds to a
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single database connection, with the name ``'default'`` describing the
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default database connection. The setting names have also been
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shortened to reflect the fact that they are stored in a dictionary.
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The sample settings given previously would now be stored using::
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DATABASES = {
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'default': {
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'NAME': 'test_db',
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'BACKEND': 'django.db.backends.postgresl_psycopg2',
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'USER': 'myusername',
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'PASSWORD': 's3krit',
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}
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}
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This affects the following settings:
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========================================= ==========================
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Old setting New Setting
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========================================= ==========================
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:setting:`DATABASE_ENGINE` :setting:`ENGINE`
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:setting:`DATABASE_HOST` :setting:`HOST`
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:setting:`DATABASE_NAME` :setting:`NAME`
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:setting:`DATABASE_OPTIONS` :setting:`OPTIONS`
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:setting:`DATABASE_PASSWORD` :setting:`PASSWORD`
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:setting:`DATABASE_PORT` :setting:`PORT`
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:setting:`DATABASE_USER` :setting:`USER`
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:setting:`TEST_DATABASE_CHARSET` :setting:`TEST_CHARSET`
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:setting:`TEST_DATABASE_COLLATION` :setting:`TEST_COLLATION`
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:setting:`TEST_DATABASE_NAME` :setting:`TEST_NAME`
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========================================= ==========================
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These changes are also required if you have manually created a database
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connection using ``DatabaseWrapper()`` from your database backend of choice.
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In addition to the change in structure, Django 1.2 removes the special
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handling for the built-in database backends. All database backends
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must now be specified by a fully qualified module name (i.e.,
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``django.db.backends.postgresl_psycopg2``, rather than just
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``postgresql_psycopg2``).
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``__dict__`` on Model instances
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-------------------------------
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Historically, the ``__dict__`` attribute of a model instance has only contained
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attributes corresponding to the fields on a model.
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In order to support multiple database configurations, Django 1.2 has
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added a ``_state`` attribute to object instances. This attribute will
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appear in ``__dict__`` for a model instance. If your code relies on
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iterating over __dict__ to obtain a list of fields, you must now
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filter out ``_state`` attribute of out ``__dict__``.
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``get_db_prep_*()`` methods on Field
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------------------------------------
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Prior to v1.2, a custom field had the option of defining several
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functions to support conversion of Python values into
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database-compatible values. A custom field might look something like::
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class CustomModelField(models.Field):
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# ...
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def get_db_prep_save(self, value):
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# ...
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def get_db_prep_value(self, value):
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# ...
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def get_db_prep_lookup(self, lookup_type, value):
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# ...
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In 1.2, these three methods have undergone a change in prototype, and
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two extra methods have been introduced::
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class CustomModelField(models.Field):
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# ...
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def get_prep_value(self, value):
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# ...
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def get_prep_lookup(self, lookup_type, value):
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# ...
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def get_db_prep_save(self, value, connection):
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# ...
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def get_db_prep_value(self, value, connection, prepared=False):
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# ...
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def get_db_prep_lookup(self, lookup_type, value, connection, prepared=False):
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# ...
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These changes are required to support multiple databases -
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``get_db_prep_*`` can no longer make any assumptions regarding the
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database for which it is preparing. The ``connection`` argument now
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provides the preparation methods with the specific connection for
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which the value is being prepared.
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The two new methods exist to differentiate general data preparation
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requirements, and requirements that are database-specific. The
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``prepared`` argument is used to indicate to the database preparation
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methods whether generic value preparation has been performed. If
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an unprepared (i.e., ``prepared=False``) value is provided to the
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``get_db_prep_*()`` calls, they should invoke the corresponding
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``get_prep_*()`` calls to perform generic data preparation.
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Conversion functions has been provided which will transparently
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convert functions adhering to the old prototype into functions
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compatible with the new prototype. However, this conversion function
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will be removed in Django 1.4, so you should upgrade your Field
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definitions to use the new prototype.
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If your ``get_db_prep_*()`` methods made no use of the database
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connection, you should be able to upgrade by renaming
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``get_db_prep_value()`` to ``get_prep_value()`` and
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``get_db_prep_lookup()`` to ``get_prep_lookup()`. If you require
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database specific conversions, then you will need to provide an
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implementation ``get_db_prep_*`` that uses the ``connection``
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argument to resolve database-specific values.
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Stateful template tags
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----------------------
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Template tags that store rendering state on the node itself may experience
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problems if they are used with the new :ref:`cached
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template loader<template-loaders>`.
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All of the built-in Django template tags are safe to use with the cached
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loader, but if you're using custom template tags that come from third
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party packages, or that you wrote yourself, you should ensure that the
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``Node`` implementation for each tag is thread-safe. For more
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information, see
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:ref:`template tag thread safety considerations<template_tag_thread_safety>`.
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.. _deprecated-features-1.2:
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Features deprecated in 1.2
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==========================
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CSRF response rewriting middleware
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----------------------------------
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``CsrfResponseMiddleware``, the middleware that automatically inserted CSRF
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tokens into POST forms in outgoing pages, has been deprecated in favor of a
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template tag method (see above), and will be removed completely in Django
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1.4. ``CsrfMiddleware``, which includes the functionality of
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``CsrfResponseMiddleware`` and ``CsrfViewMiddleware`` has likewise been
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deprecated.
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Also, the CSRF module has moved from contrib to core, and the old imports are
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deprecated, as described in the :ref:`upgrading notes <ref-csrf-upgrading-notes>`.
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``SMTPConnection``
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------------------
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The ``SMTPConnection`` class has been deprecated in favor of a generic
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E-mail backend API. Old code that explicitly instantiated an instance
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of an SMTPConnection::
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from django.core.mail import SMTPConnection
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connection = SMTPConnection()
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messages = get_notification_email()
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connection.send_messages(messages)
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should now call :meth:`~django.core.mail.get_connection()` to
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instantiate a generic e-mail connection::
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from django.core.mail import get_connection
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connection = get_connection()
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messages = get_notification_email()
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connection.send_messages(messages)
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Depending on the value of the :setting:`EMAIL_BACKEND` setting, this
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may not return an SMTP connection. If you explicitly require an SMTP
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connection with which to send e-mail, you can explicitly request an
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SMTP connection::
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from django.core.mail import get_connection
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connection = get_connection('django.core.mail.backends.smtp')
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messages = get_notification_email()
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connection.send_messages(messages)
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If your call to construct an instance of ``SMTPConnection`` required
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additional arguments, those arguments can be passed to the
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:meth:`~django.core.mail.get_connection()` call::
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connection = get_connection('django.core.mail.backends.smtp', hostname='localhost', port=1234)
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User Messages API
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-----------------
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The API for storing messages in the user ``Message`` model (via
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``user.message_set.create``) is now deprecated and will be removed in Django
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1.4 according to the standard :ref:`release process <internals-release-process>`.
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To upgrade your code, you need to replace any instances of::
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user.message_set.create('a message')
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with the following::
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from django.contrib import messages
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messages.add_message(request, messages.INFO, 'a message')
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Additionally, if you make use of the method, you need to replace the
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following::
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for message in user.get_and_delete_messages():
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...
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with::
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from django.contrib import messages
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for message in messages.get_messages(request):
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...
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For more information, see the full
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:ref:`messages documentation <ref-contrib-messages>`. You should begin to
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update your code to use the new API immediately.
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Date format helper functions
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----------------------------
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``django.utils.translation.get_date_formats()`` and
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``django.utils.translation.get_partial_date_formats()`` have been deprecated
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in favor of the appropriate calls to ``django.utils.formats.get_format()``
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which is locale aware when :setting:`USE_L10N` is set to ``True``, and falls
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back to default settings if set to ``False``.
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To get the different date formats, instead of writing::
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from django.utils.translation import get_date_formats
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date_format, datetime_format, time_format = get_date_formats()
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use::
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from django.utils import formats
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date_format = formats.get_format('DATE_FORMAT')
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datetime_format = formats.get_format('DATETIME_FORMAT')
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time_format = formats.get_format('TIME_FORMAT')
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or, when directly formatting a date value::
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from django.utils import formats
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value_formatted = formats.date_format(value, 'DATETIME_FORMAT')
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The same applies to the globals found in ``django.forms.fields``:
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* ``DEFAULT_DATE_INPUT_FORMATS``
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* ``DEFAULT_TIME_INPUT_FORMATS``
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* ``DEFAULT_DATETIME_INPUT_FORMATS``
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Use ``django.utils.formats.get_format()`` to get the appropriate formats.
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What's new in Django 1.2
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========================
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CSRF support
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------------
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Django now has much improved protection against :ref:`Cross-Site
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Request Forgery (CSRF) attacks<ref-contrib-csrf>`. This type of attack
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occurs when a malicious Web site contains a link, a form button or
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some javascript that is intended to perform some action on your Web
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site, using the credentials of a logged-in user who visits the
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malicious site in their browser. A related type of attack, 'login
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CSRF', where an attacking site tricks a user's browser into logging
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into a site with someone else's credentials, is also covered.
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E-mail Backends
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---------------
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You can now :ref:`configure the way that Django sends e-mail
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<topic-email-backends>`. Instead of using SMTP to send all e-mail, you
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can now choose a configurable e-mail backend to send messages. If your
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hosting provider uses a sandbox or some other non-SMTP technique for
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sending mail, you can now construct an e-mail backend that will allow
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Django's standard :ref:`mail sending methods<topics-email>` to use
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those facilities.
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This also makes it easier to debug mail sending - Django ships with
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backend implementations that allow you to send e-mail to a
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:ref:`file<topic-email-file-backend>`, to the
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:ref:`console<topic-email-console-backend>`, or to
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:ref:`memory<topic-email-memory-backend>` - you can even configure all
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e-mail to be :ref:`thrown away<topic-email-dummy-backend>`.
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Messages Framework
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------------------
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Django now includes a robust and configurable :ref:`messages framework
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<ref-contrib-messages>` with built-in support for cookie- and session-based
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messaging, for both anonymous and authenticated clients. The messages framework
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replaces the deprecated user message API and allows you to temporarily store
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messages in one request and retrieve them for display in a subsequent request
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(usually the next one).
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Support for multiple databases
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------------------------------
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Django 1.2 adds the ability to use :ref:`more than one database
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<topics-db-multi-db>` in your Django project. Queries can be
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issued at a specific database with the `using()` method on
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querysets; individual objects can be saved to a specific database
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by providing a ``using`` argument when you save the instance.
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'Smart' if tag
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--------------
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The :ttag:`if` tag has been upgraded to be much more powerful. First, support
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for comparison operators has been added. No longer will you have to type:
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.. code-block:: html+django
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{% ifnotequal a b %}
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...
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{% endifnotequal %}
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...as you can now do:
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.. code-block:: html+django
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{% if a != b %}
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...
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{% endif %}
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The operators supported are ``==``, ``!=``, ``<``, ``>``, ``<=``, ``>=`` and
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``in``, all of which work like the Python operators, in addition to ``and``,
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``or`` and ``not`` which were already supported.
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Also, filters may now be used in the ``if`` expression. For example:
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.. code-block:: html+django
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<div
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{% if user.email|lower == message.recipient|lower %}
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class="highlight"
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{% endif %}
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>{{ message }}</div>
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Template caching
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----------------
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In previous versions of Django, every time you rendered a template it
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would be reloaded from disk. In Django 1.2, you can use a :ref:`cached
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template loader <template-loaders>` to load templates once, then use a
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cached the result for every subsequent render. This can lead to a
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significant performance improvement if your templates are broken into
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lots of smaller subtemplates (using the ``{% extends %}`` or ``{%
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include %}`` tags).
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As a side effect, it is now much easier to support non-Django template
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languages. For more details, see the :ref:`notes on supporting
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non-Django template languages<topic-template-alternate-language>`.
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Natural keys in fixtures
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------------------------
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Fixtures can refer to remote objects using
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:ref:`topics-serialization-natural-keys`. This lookup scheme is an
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alternative to the normal primary-key based object references in a
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fixture, improving readability, and resolving problems referring to
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objects whose primary key value may not be predictable or known.
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``BigIntegerField``
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-------------------
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Models can now use a 64 bit :class:`~django.db.models.BigIntegerField` type.
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Fast Failure for Tests
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----------------------
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The :djadmin:`test` subcommand of ``django-admin.py``, and the ``runtests.py``
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script used to run Django's own test suite, support a new ``--failfast`` option.
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When specified, this option causes the test runner to exit after encountering
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a failure instead of continuing with the test run. In addition, the handling
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of ``Ctrl-C`` during a test run has been improved to trigger a graceful exit
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from the test run that reports details of the tests run before the interruption.
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Improved localization
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---------------------
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Django's :ref:`internationalization framework <topics-i18n>` has been
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expanded by locale aware formatting and form processing. That means, if
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enabled, dates and numbers on templates will be displayed using the format
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specified for the current locale. Django will also use localized formats
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when parsing data in forms.
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See :ref:`Format localization <format-localization>` for more details.
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Added ``readonly_fields`` to ``ModelAdmin``
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-------------------------------------------
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:attr:`django.contrib.admin.ModelAdmin.readonly_fields` has been added to
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enable non-editable fields in add/change pages for models and inlines. Field
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and calculated values can be displayed along side editable fields.
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Customizable syntax highlighting
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--------------------------------
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You can now use the ``DJANGO_COLORS`` environment variable to modify
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or disable the colors used by ``django-admin.py`` to provide
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:ref:`syntax highlighting <syntax-coloring>`.
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