Django 1.4 beta release notes¶

Support for in-browser testing frameworks¶

Django 1.4 supports integration with in-browser testing frameworks like Selenium. The new django.test.LiveServerTestCase base class lets you test the interactions between your site’s front and back ends more comprehensively. See the documentation for more details and concrete examples.

SELECT FOR UPDATE support¶

Django 1.4 now includes a QuerySet.select_for_update() method which generates a SELECT ... FOR UPDATE SQL query. This will lock rows until the end of the transaction, meaning that other transactions cannot modify or delete rows matched by a FOR UPDATE query.

For more details, see the documentation for 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 database setup for test suites) have seen a performance benefit as a result.

See the bulk_create() docs for more information.

QuerySet.prefetch_related¶

Similar to select_related() but with a different strategy and broader scope, prefetch_related() has been added to 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.

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 How Django stores passwords.

from base64 import b64decode
from django.contrib.auth.models import User
hash_len = {'pbkdf2_sha1': 20, 'pbkdf2_sha256': 32}
for user in User.objects.filter(password__startswith='pbkdf2_'):
    algo, _, _, hash = user.password.split('$')
    if len(b64decode(hash)) != hash_len[algo]:
        print user

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 admin app allowed you to specify change list filters by specifying a field lookup, but 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 list_filter.

Multiple sort in admin interface¶

The admin change list now supports sorting on multiple columns. It respects all elements of the ordering attribute, and sorting on multiple columns by clicking on headers is designed to mimic the behavior of desktop GUIs. The get_ordering() method for specifying the ordering dynamically (e.g. depending on the request) has also been added.

New ModelAdmin methods¶

A new save_related() method was added to ModelAdmin to ease customization of how related objects are saved in the admin.

Two other new methods, get_list_display() and get_list_display_links() were added to ModelAdmin to enable the dynamic customization 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 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 cryptographic signing docs for more information.

Cookie-based session backend¶

Django 1.4 introduces a new cookie-based backend for the session framework which uses the tools for cryptographic signing to store the session data in the client’s browser.

See the cookie-based session backend docs for more information.

New form wizard¶

The previous FormWizard from the formtools contrib app 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 cryptographic signing also introduced in Django 1.4 to store the wizard’s state in the user’s cookies.

See the form wizard docs for more information.

reverse_lazy¶

A lazily evaluated version of django.core.urlresolvers.reverse() was added 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 pattern when using the new i18n_patterns() helper function. Additionally, it’s now possible to define translatable URL patterns using ugettext_lazy(). See Internationalization: in URL patterns for more information about the language prefix and how to internationalize URL patterns.

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

The contextual translation support introduced in Django 1.3 via the pgettext function has been extended to the trans and blocktrans template tags using the new context keyword.

Customizable SingleObjectMixin URLConf kwargs¶

Two new attributes, pk_url_kwarg and slug_url_kwarg, have been added to 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 simple_tag, inclusion_tag 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:

{% 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¶

Added a filter which 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 truncatechars for more details.

static template tag¶

The staticfiles contrib app has a new static template tag to refer to files saved with the STATICFILES_STORAGE storage backend. It uses the storage backend’s url method and therefore supports advanced features such as serving files from a cloud service.

CachedStaticFilesStorage storage backend¶

In addition to the static template tag, the staticfiles contrib app now has a CachedStaticFilesStorage backend which caches the files it saves (when running the 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 CachedStaticFilesStorage docs for more information.

Simple clickjacking protection¶

We’ve added a middleware to provide easy protection against clickjacking using the X-Frame-Options header. It’s not enabled by default for backwards compatibility reasons, but you’ll almost certainly want to enable it 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 ensure_csrf_cookie() decorator which can help with AJAX heavy sites, protection for PUT and DELETE requests, and the CSRF_COOKIE_SECURE and CSRF_COOKIE_PATH settings which can improve the security and usefulness of the CSRF protection. See the CSRF docs for more information.

Error report filtering¶

Two new function decorators, sensitive_variables() and sensitive_post_parameters(), were added to allow designating the local variables and POST parameters which 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 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 may override or customize the default filtering by writing a custom filter. For more information see the docs on Filtering error reports.

Extended IPv6 support¶

The previously added support for IPv6 addresses when using the runserver management command in Django 1.3 has now been further extended by adding a GenericIPAddressField model field, a GenericIPAddressField form field and the validators validate_ipv46_address and validate_ipv6_address

Updated default project layout and manage.py¶

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

Improved WSGI support¶

The startproject management command now adds a wsgi.py module to the initial project layout, containing a simple WSGI application that can be used for deploying with WSGI app servers.

The built-in development server now supports using an externally-defined WSGI callable, so as to make it possible to run runserver with the same WSGI configuration that is used for deployment. A new WSGI_APPLICATION setting is available to configure which WSGI callable runserver uses.

(The runfcgi management command also internally wraps the WSGI callable configured via WSGI_APPLICATION.)

Custom project and app templates¶

The startapp and startproject management commands got 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 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 second argument to both startapp and startproject:

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

For more information, see the startapp and startproject documentation.

Support for time zones¶

Django 1.4 adds support for time zones. When it’s enabled, 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 startproject. If you want to use this feature in an existing project, there is a migration guide.

Two new date format strings¶

Two new date formats were added for use in template filters, template tags and Format localization:

• e – the name of the timezone of the given datetime object
• o – the ISO 8601 year number

Please make sure to update your 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 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 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.

• Tablespace support in PostgreSQL.

• Customizable names for simple_tag().

• In the documentation, a helpful security overview 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 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 django.conf.urls.handler403. See the documentation about the 403 (HTTP Forbidden) view for more information.

• The 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 if template tag now supports {% elif %} clauses.

• A new plain text version of the HTTP 500 status code internal error page served when DEBUG is True is now sent to the client when Django detects that the request has originated in JavaScript code (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 --no-location option to the 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 distinct().

• New phrases added to HIDDEN_SETTINGS regex in django/views/debug.py.

  'API', 'TOKEN', 'KEY' were added, 'PASSWORD' was changed to 'PASS'.

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 it easier to deploy the included files. 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 are served by a web server. This setting has now been deprecated and replaced by the more general 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 STATIC_URL and STATIC_ROOT are configured and your web server serves the files correctly. The development server continues to serve the admin files just like before. Don’t hesitate to consult the static files howto for further details.

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 STATIC_URL setting to the correct URL, for example http://media.example.com/.

Supported browsers for the admin¶

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

Released over ten 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.

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

Removed admin icons¶

As part of an effort to improve the performance and usability of the admin’s changelist sorting interface and of the admin’s horizontal and 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 will want to replace them 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 the form field names in the main admin forms, stacked inline forms and tabular inline cells. You will 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 SESSION_COOKIE_AGE.
• contrib.auth password reset hash
  • consequences: password reset links from before the upgrade will not work.
  • time period: defined by PASSWORD_RESET_TIMEOUT_DAYS.

Form-related hashes — these 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 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 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. Additionally redirects returned by flatpages are now permanent (301 status code) to match the behavior of the CommonMiddleware.

Serialization of datetime and time¶

As a consequence of time zone support, and according to the ECMA-262 specification, 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, instead of a space. Time zone information is included in the [+-]HH:MM format.

The serializers will dump datetimes in fixtures with these new formats. 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 USE_TZ is False, if you attempt to save an aware datetime object, 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 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 is now possible to pass connections between threads, Django does 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 comments app 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, simply 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(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 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()

For more details, see the documentation about customizing the comments framework.

IGNORABLE_404_STARTS and IGNORABLE_404_ENDS settings¶

Until Django 1.3, it was possible to exclude some URLs from Django’s 404 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 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 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.

CSRF protection extended to PUT and DELETE¶

Previously, Django’s CSRF protection provided protection against only 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 enforce protection on everything else.

If you are using PUT or DELETE methods in AJAX applications, please see the instructions about using AJAX and CSRF.

django.core.template_loaders¶

This was an alias to django.template.loader since 2005, it has been removed without emitting a warning due to the length of the deprecation. If your code still referenced this please use django.template.loader instead.

django.db.models.fields.URLField.verify_exists¶

This functionality has been removed due to intractable performance and security issues. Any existing usage of verify_exists should be removed.

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 the returned 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 trigger arbitrary code execution if you process a YAML document that comes from an untrusted source. This feature isn’t necessary for Django’s YAML deserializer, whose primary use is to load fixtures consisting of simple objects. Even though fixtures are trusted data, for additional security, the YAML deserializer now uses yaml.safe_load.

Old styles of calling cache_page decorator¶

Some legacy ways of calling cache_page() have been deprecated, please see the docs for the correct way to use this decorator.

Support for PostgreSQL versions older than 8.2¶

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

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

Request exceptions are now always logged¶

When logging support was added to Django in 1.3, the admin error email support was moved into the django.utils.log.AdminEmailHandler, attached to the 'django.request' logger. In order to maintain the established behavior of error emails, the 'django.request' logger was called only when DEBUG was False.

To increase the flexibility of error logging for requests, the 'django.request' logger is now called regardless of the value of DEBUG, and the default settings file for new projects now includes a separate filter attached to django.utils.log.AdminEmailHandler to prevent 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 LOGGING setting will not include this new filter. In order to maintain backwards-compatibility, Django will detect that your 'mail_admins' handler configuration includes no 'filters' section, and will automatically add this filter for you and issue a pending-deprecation warning. This will become a deprecation warning in Django 1.5, and in Django 1.6 the backwards-compatibility shim will be removed entirely.

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

django.conf.urls.defaults¶

Until Django 1.3 the functions include(), patterns() and url() plus handler404, handler500 were located in a django.conf.urls.defaults module.

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

django.contrib.databrowse¶

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

The code that powers Databrowse is licensed under the same terms as Django itself, and so is available to be adopted by an individual or group as a 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 startproject layout. This function is now deprecated, as its path workarounds are no longer needed with the new manage.py and default project layout.

This function was never documented or part of the public API, but was widely recommended 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 django.conf.settings.configure().

django.core.management.execute_manager¶

This function was previously used by manage.py to execute a management command. It is identical to django.core.management.execute_from_command_line, except that it first calls setup_environ, which is now deprecated. As such, execute_manager is also deprecated; execute_from_command_line can be used instead. Neither of these functions is documented as part of the public API, but a deprecation path 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 filter interacts with Django’s auto-escaping behavior. They used to be attributes of the filter function:

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

However, this technique caused some problems in combination with decorators, especially @stringfilter. Now, the flags are keyword arguments of @register.filter:

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

See filters and auto-escaping for more information.

Session cookies now have the httponly flag by default¶

Session cookies now include the httponly attribute by default to help reduce the impact of potential XSS attacks. As a consequence of this change, session cookie data, including sessionid, is no longer accessible from Javascript in many browsers. For strict backwards compatibility, use SESSION_COOKIE_HTTPONLY = False in your settings file.

Wildcard expansion of application names in INSTALLED_APPS¶

Until Django 1.3, INSTALLED_APPS accepted wildcards in application names, like django.contrib.*. The expansion was performed by a filesystem-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 obviously useful, it was removed in Django 1.4. If you relied on it, you must edit your settings file to list all your applications explicitly.

HttpRequest.raw_post_data renamed to HttpRequest.body¶

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