========================= Django 1.6 release notes ========================= .. note:: Dedicated to Malcolm Tredinnick On March 17, 2013, the Django project and the free software community lost a very dear friend and developer. Malcolm was a long-time contributor to Django, a model community member, a brilliant mind, and a friend. His contributions to Django — and to many other open source projects — are nearly impossible to enumerate. Many on the core Django team had their first patches reviewed by him; his mentorship enriched us. His consideration, patience, and dedication will always be an inspiration to us. This release of Django is for Malcolm. -- The Django Developers *November 6, 2013* Welcome to Django 1.6! These release notes cover the `new features`_, as well as some `backwards incompatible changes`_ you'll want to be aware of when upgrading from Django 1.5 or older versions. We've also dropped some features, which are detailed in :doc:`our deprecation plan `, and we've `begun the deprecation process for some features`_. .. _`new features`: `What's new in Django 1.6`_ .. _`backwards incompatible changes`: `Backwards incompatible changes in 1.6`_ .. _`begun the deprecation process for some features`: `Features deprecated in 1.6`_ Python compatibility ==================== Django 1.6, like Django 1.5, requires Python 2.6.5 or above. Python 3 is also officially supported. We **highly recommend** the latest minor release for each supported Python series (2.6.X, 2.7.X, 3.2.X, and 3.3.X). Django 1.6 will be the final release series to support Python 2.6; beginning with Django 1.7, the minimum supported Python version will be 2.7. What's new in Django 1.6 ======================== Simplified default project and app templates ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The default templates used by :djadmin:`startproject` and :djadmin:`startapp` have been simplified and modernized. The :doc:`admin ` is now enabled by default in new projects; the :doc:`sites ` framework no longer is. :ref:`clickjacking prevention ` is now on and the database defaults to SQLite. If the default templates don't suit your tastes, you can use :ref:`custom project and app templates `. Improved transaction management ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Django's transaction management was overhauled. Database-level autocommit is now turned on by default. This makes transaction handling more explicit and should improve performance. The existing APIs were deprecated, and new APIs were introduced, as described in the :doc:`transaction management docs `. Please review carefully the list of :ref:`known backwards-incompatibilities ` to determine if you need to make changes in your code. Persistent database connections ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Django now supports reusing the same database connection for several requests. This avoids the overhead of re-establishing a connection at the beginning of each request. For backwards compatibility, this feature is disabled by default. See :ref:`persistent-database-connections` for details. Discovery of tests in any test module ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Django 1.6 ships with a new test runner that allows more flexibility in the location of tests. The previous runner (``django.test.simple.DjangoTestSuiteRunner``) found tests only in the ``models.py`` and ``tests.py`` modules of a Python package in :setting:`INSTALLED_APPS`. The new runner (``django.test.runner.DiscoverRunner``) uses the test discovery features built into ``unittest2`` (the version of ``unittest`` in the Python 2.7+ standard library, and bundled with Django). With test discovery, tests can be located in any module whose name matches the pattern ``test*.py``. In addition, the test labels provided to ``./manage.py test`` to nominate specific tests to run must now be full Python dotted paths (or directory paths), rather than ``applabel.TestCase.test_method_name`` pseudo-paths. This allows running tests located anywhere in your codebase, rather than only in :setting:`INSTALLED_APPS`. For more details, see :doc:`/topics/testing/index`. This change is backwards-incompatible; see the :ref:`backwards-incompatibility notes`. Time zone aware aggregation ~~~~~~~~~~~~~~~~~~~~~~~~~~~ The support for :doc:`time zones ` introduced in Django 1.4 didn't work well with :meth:`QuerySet.dates() `: aggregation was always performed in UTC. This limitation was lifted in Django 1.6. Use :meth:`QuerySet.datetimes() ` to perform time zone aware aggregation on a :class:`~django.db.models.DateTimeField`. Support for savepoints in SQLite ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Django 1.6 adds support for savepoints in SQLite, with some :ref:`limitations `. ``BinaryField`` model field ~~~~~~~~~~~~~~~~~~~~~~~~~~~ A new :class:`django.db.models.BinaryField` model field allows storage of raw binary data in the database. GeoDjango form widgets ~~~~~~~~~~~~~~~~~~~~~~ GeoDjango now provides :ref:`form fields and widgets ` for its geo-specialized fields. They are OpenLayers-based by default, but they can be customized to use any other JS framework. ``check`` management command added for verifying compatibility ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A :djadmin:`check` management command was added, enabling you to verify if your current configuration (currently oriented at settings) is compatible with the current version of Django. :meth:`Model.save() ` algorithm changed ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The :meth:`Model.save() ` method now tries to directly ``UPDATE`` the database if the instance has a primary key value. Previously ``SELECT`` was performed to determine if ``UPDATE`` or ``INSERT`` were needed. The new algorithm needs only one query for updating an existing row while the old algorithm needed two. See :meth:`Model.save() ` for more details. In some rare cases the database doesn't report that a matching row was found when doing an ``UPDATE``. An example is the PostgreSQL ``ON UPDATE`` trigger which returns ``NULL``. In such cases it is possible to set :attr:`django.db.models.Options.select_on_save` flag to force saving to use the old algorithm. Minor features ~~~~~~~~~~~~~~ * Authentication backends can raise ``PermissionDenied`` to immediately fail the authentication chain. * The ``HttpOnly`` flag can be set on the CSRF cookie with :setting:`CSRF_COOKIE_HTTPONLY`. * The :meth:`~django.test.TransactionTestCase.assertQuerysetEqual` now checks for undefined order and raises :exc:`~exceptions.ValueError` if undefined order is spotted. The order is seen as undefined if the given ``QuerySet`` isn't ordered and there are more than one ordered values to compare against. * Added :meth:`~django.db.models.query.QuerySet.earliest` for symmetry with :meth:`~django.db.models.query.QuerySet.latest`. * In addition to :lookup:`year`, :lookup:`month` and :lookup:`day`, the ORM now supports :lookup:`hour`, :lookup:`minute` and :lookup:`second` lookups. * Django now wraps all PEP-249 exceptions. * The default widgets for :class:`~django.forms.EmailField`, :class:`~django.forms.URLField`, :class:`~django.forms.IntegerField`, :class:`~django.forms.FloatField` and :class:`~django.forms.DecimalField` use the new type attributes available in HTML5 (``type='email'``, ``type='url'``, ``type='number'``). Note that due to erratic support of the ``number`` input type with localized numbers in current browsers, Django only uses it when numeric fields are not localized. * The ``number`` argument for :ref:`lazy plural translations ` can be provided at translation time rather than at definition time. * For custom management commands: Verification of the presence of valid settings in commands that ask for it by using the :attr:`~django.core.management.BaseCommand.can_import_settings` internal option is now performed independently from handling of the locale that should be active during the execution of the command. The latter can now be influenced by the new :attr:`~django.core.management.BaseCommand.leave_locale_alone` internal option. See :ref:`management-commands-and-locales` for more details. * The :attr:`~django.views.generic.edit.DeletionMixin.success_url` of :class:`~django.views.generic.edit.DeletionMixin` is now interpolated with its ``object``’s ``__dict__``. * :class:`~django.http.HttpResponseRedirect` and :class:`~django.http.HttpResponsePermanentRedirect` now provide an ``url`` attribute (equivalent to the URL the response will redirect to). * The ``MemcachedCache`` cache backend now uses the latest :mod:`pickle` protocol available. * Added :class:`~django.contrib.messages.views.SuccessMessageMixin` which provides a ``success_message`` attribute for :class:`~django.views.generic.edit.FormView` based classes. * Added the :attr:`django.db.models.ForeignKey.db_constraint` and :attr:`django.db.models.ManyToManyField.db_constraint` options. * The jQuery library embedded in the admin has been upgraded to version 1.9.1. * Syndication feeds (:mod:`django.contrib.syndication`) can now pass extra context through to feed templates using a new :meth:`Feed.get_context_data() ` callback. * The admin list columns have a ``column-`` class in the HTML so the columns header can be styled with CSS, e.g. to set a column width. * The :ref:`isolation level` can be customized under PostgreSQL. * The :ttag:`blocktrans` template tag now respects :setting:`TEMPLATE_STRING_IF_INVALID` for variables not present in the context, just like other template constructs. * ``SimpleLazyObject``\s will now present more helpful representations in shell debugging situations. * Generic :class:`~django.contrib.gis.db.models.GeometryField` is now editable with the OpenLayers widget in the admin. * The documentation contains a :doc:`deployment checklist `. * The :djadmin:`diffsettings` command gained a ``--all`` option. * ``django.forms.fields.Field.__init__`` now calls ``super()``, allowing field mixins to implement ``__init__()`` methods that will reliably be called. * The ``validate_max`` parameter was added to ``BaseFormSet`` and :func:`~django.forms.formsets.formset_factory`, and ``ModelForm`` and inline versions of the same. The behavior of validation for formsets with ``max_num`` was clarified. The previously undocumented behavior that hardened formsets against memory exhaustion attacks was documented, and the undocumented limit of the higher of 1000 or ``max_num`` forms was changed so it is always 1000 more than ``max_num``. * Added ``BCryptSHA256PasswordHasher`` to resolve the password truncation issue with bcrypt. * `Pillow`_ is now the preferred image manipulation library to use with Django. `PIL`_ is pending deprecation (support to be removed in Django 1.8). To upgrade, you should **first** uninstall PIL, **then** install Pillow. .. _`Pillow`: https://pypi.python.org/pypi/Pillow .. _`PIL`: https://pypi.python.org/pypi/PIL * :class:`~django.forms.ModelForm` accepts several new ``Meta`` options. * Fields included in the ``localized_fields`` list will be localized (by setting ``localize`` on the form field). * The ``labels``, ``help_texts`` and ``error_messages`` options may be used to customize the default fields, see :ref:`modelforms-overriding-default-fields` for details. * The ``choices`` argument to model fields now accepts an iterable of iterables instead of requiring an iterable of lists or tuples. * The reason phrase can be customized in HTTP responses using :attr:`~django.http.HttpResponse.reason_phrase`. * When giving the URL of the next page for :func:`~django.contrib.auth.views.logout`, :func:`~django.contrib.auth.views.password_reset`, :func:`~django.contrib.auth.views.password_reset_confirm`, and :func:`~django.contrib.auth.views.password_change`, you can now pass URL names and they will be resolved. * The :djadmin:`dumpdata` ``manage.py`` command now has a :djadminopt:`--pks` option which will allow users to specify the primary keys of objects they want to dump. This option can only be used with one model. * Added ``QuerySet`` methods :meth:`~django.db.models.query.QuerySet.first` and :meth:`~django.db.models.query.QuerySet.last` which are convenience methods returning the first or last object matching the filters. Returns ``None`` if there are no objects matching. * :class:`~django.views.generic.base.View` and :class:`~django.views.generic.base.RedirectView` now support HTTP ``PATCH`` method. * ``GenericForeignKey`` now takes an optional ``for_concrete_model`` argument, which when set to ``False`` allows the field to reference proxy models. The default is ``True`` to retain the old behavior. * The :class:`~django.middleware.locale.LocaleMiddleware` now stores the active language in session if it is not present there. This prevents loss of language settings after session flush, e.g. logout. * :exc:`~django.core.exceptions.SuspiciousOperation` has been differentiated into a number of subclasses, and each will log to a matching named logger under the ``django.security`` logging hierarchy. Along with this change, a ``handler400`` mechanism and default view are used whenever a ``SuspiciousOperation`` reaches the WSGI handler to return an ``HttpResponseBadRequest``. * The :exc:`~django.core.exceptions.DoesNotExist` exception now includes a message indicating the name of the attribute used for the lookup. * The :meth:`~django.db.models.query.QuerySet.get_or_create` method no longer requires at least one keyword argument. * The :class:`~django.test.SimpleTestCase` class includes a new assertion helper for testing formset errors: :meth:`~django.test.SimpleTestCase.assertFormsetError`. * The list of related fields added to a :class:`~django.db.models.query.QuerySet` by :meth:`~django.db.models.query.QuerySet.select_related` can be cleared using ``select_related(None)``. * The :meth:`~django.contrib.admin.InlineModelAdmin.get_extra` and :meth:`~django.contrib.admin.InlineModelAdmin.get_max_num` methods on :class:`~django.contrib.admin.InlineModelAdmin` may be overridden to customize the extra and maximum number of inline forms. * Formsets now have a :meth:`~django.forms.formsets.BaseFormSet.total_error_count` method. * :class:`~django.forms.ModelForm` fields can now override error messages defined in model fields by using the :attr:`~django.forms.Field.error_messages` argument of a ``Field``’s constructor. To take advantage of this new feature with your custom fields, :ref:`see the updated recommendation ` for raising a ``ValidationError``. * :class:`~django.contrib.admin.ModelAdmin` now preserves filters on the list view after creating, editing or deleting an object. It's possible to restore the previous behavior of clearing filters by setting the :attr:`~django.contrib.admin.ModelAdmin.preserve_filters` attribute to ``False``. * Added :meth:`FormMixin.get_prefix` (which returns :attr:`FormMixin.prefix` by default) to allow customizing the :attr:`~django.forms.Form.prefix` of the form. * Raw queries (``Manager.raw()`` or ``cursor.execute()``) can now use the "pyformat" parameter style, where placeholders in the query are given as ``'%(name)s'`` and the parameters are passed as a dictionary rather than a list (except on SQLite). This has long been possible (but not officially supported) on MySQL and PostgreSQL, and is now also available on Oracle. * The default iteration count for the PBKDF2 password hasher has been increased by 20%. This backwards compatible change will not affect existing passwords or users who have subclassed ``django.contrib.auth.hashers.PBKDF2PasswordHasher`` to change the default value. Passwords :ref:`will be upgraded ` to use the new iteration count as necessary. Backwards incompatible changes in 1.6 ===================================== .. warning:: In addition to the changes outlined in this section, be sure to review the :doc:`deprecation plan ` for any features that have been removed. If you haven't updated your code within the deprecation timeline for a given feature, its removal may appear as a backwards incompatible change. New transaction management model ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Behavior changes ^^^^^^^^^^^^^^^^ Database-level autocommit is enabled by default in Django 1.6. While this doesn't change the general spirit of Django's transaction management, there are a few known backwards-incompatibilities, described in the :ref:`transaction management docs `. You should review your code to determine if you're affected. Savepoints and ``assertNumQueries`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The changes in transaction management may result in additional statements to create, release or rollback savepoints. This is more likely to happen with SQLite, since it didn't support savepoints until this release. If tests using :meth:`~django.test.TransactionTestCase.assertNumQueries` fail because of a higher number of queries than expected, check that the extra queries are related to savepoints, and adjust the expected number of queries accordingly. Autocommit option for PostgreSQL ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ In previous versions, database-level autocommit was only an option for PostgreSQL, and it was disabled by default. This option is now :ref:`ignored ` and can be removed. .. _new-test-runner: New test runner ~~~~~~~~~~~~~~~ In order to maintain greater consistency with Python's unittest module, the new test runner (``django.test.runner.DiscoverRunner``) does not automatically support some types of tests that were supported by the previous runner: * Tests in ``models.py`` and ``tests/__init__.py`` files will no longer be found and run. Move them to a file whose name begins with ``test``. * Doctests will no longer be automatically discovered. To integrate doctests in your test suite, follow the `recommendations in the Python documentation`_. Django bundles a modified version of the :mod:`doctest` module from the Python standard library (in ``django.test._doctest``) and includes some additional doctest utilities. These utilities are deprecated and will be removed in Django 1.8; doctest suites should be updated to work with the standard library's doctest module (or converted to unittest-compatible tests). If you wish to delay updates to your test suite, you can set your :setting:`TEST_RUNNER` setting to ``django.test.simple.DjangoTestSuiteRunner`` to fully restore the old test behavior. ``DjangoTestSuiteRunner`` is deprecated but will not be removed from Django until version 1.8. .. _recommendations in the Python documentation: http://docs.python.org/2/library/doctest.html#unittest-api Custom User models in tests ~~~~~~~~~~~~~~~~~~~~~~~~~~~ The introduction of the new test runner has also slightly changed the way that test models are imported. As a result, any test that overrides ``AUTH_USER_MODEL`` to test behavior with one of Django's test user models ( :class:`~django.contrib.auth.tests.custom_user.CustomUser` and :class:`~django.contrib.auth.tests.custom_user.ExtensionUser`) must now explicitly import the User model in your test module:: from django.contrib.auth.tests.custom_user import CustomUser @override_settings(AUTH_USER_MODEL='auth.CustomUser') class CustomUserFeatureTests(TestCase): def test_something(self): # Test code here ... This import forces the custom user model to be registered. Without this import, the test will be unable to swap in the custom user model, and you will get an error reporting:: ImproperlyConfigured: AUTH_USER_MODEL refers to model 'auth.CustomUser' that has not been installed Time zone-aware ``day``, ``month``, and ``week_day`` lookups ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Django 1.6 introduces time zone support for :lookup:`day`, :lookup:`month`, and :lookup:`week_day` lookups when :setting:`USE_TZ` is ``True``. These lookups were previously performed in UTC regardless of the current time zone. This requires :ref:`time zone definitions in the database `. If you're using SQLite, you must install pytz_. If you're using MySQL, you must install pytz_ and load the time zone tables with `mysql_tzinfo_to_sql`_. .. _pytz: http://pytz.sourceforge.net/ .. _mysql_tzinfo_to_sql: http://dev.mysql.com/doc/refman/5.5/en/mysql-tzinfo-to-sql.html Addition of ``QuerySet.datetimes()`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When the :doc:`time zone support ` added in Django 1.4 was active, :meth:`QuerySet.dates() ` lookups returned unexpected results, because the aggregation was performed in UTC. To fix this, Django 1.6 introduces a new API, :meth:`QuerySet.datetimes() `. This requires a few changes in your code. ``QuerySet.dates()`` returns ``date`` objects ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ :meth:`QuerySet.dates() ` now returns a list of :class:`~datetime.date`. It used to return a list of :class:`~datetime.datetime`. :meth:`QuerySet.datetimes() ` returns a list of :class:`~datetime.datetime`. ``QuerySet.dates()`` no longer usable on ``DateTimeField`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ :meth:`QuerySet.dates() ` raises an error if it's used on :class:`~django.db.models.DateTimeField` when time zone support is active. Use :meth:`QuerySet.datetimes() ` instead. ``date_hierarchy`` requires time zone definitions ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The :attr:`~django.contrib.admin.ModelAdmin.date_hierarchy` feature of the admin now relies on :meth:`QuerySet.datetimes() ` when it's used on a :class:`~django.db.models.DateTimeField`. This requires time zone definitions in the database when :setting:`USE_TZ` is ``True``. :ref:`Learn more `. ``date_list`` in generic views requires time zone definitions ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ For the same reason, accessing ``date_list`` in the context of a date-based generic view requires time zone definitions in the database when the view is based on a :class:`~django.db.models.DateTimeField` and :setting:`USE_TZ` is ``True``. :ref:`Learn more `. New lookups may clash with model fields ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Django 1.6 introduces ``hour``, ``minute``, and ``second`` lookups on :class:`~django.db.models.DateTimeField`. If you had model fields called ``hour``, ``minute``, or ``second``, the new lookups will clash with you field names. Append an explicit :lookup:`exact` lookup if this is an issue. ``BooleanField`` no longer defaults to ``False`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When a :class:`~django.db.models.BooleanField` doesn't have an explicit :attr:`~django.db.models.Field.default`, the implicit default value is ``None``. In previous version of Django, it was ``False``, but that didn't represent accurately the lack of a value. Code that relies on the default value being ``False`` may raise an exception when saving new model instances to the database, because ``None`` isn't an acceptable value for a :class:`~django.db.models.BooleanField`. You should either specify ``default=False`` in the field definition, or ensure the field is set to ``True`` or ``False`` before saving the object. Translations and comments in templates ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Extraction of translations after comments ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Extraction of translatable literals from templates with the :djadmin:`makemessages` command now correctly detects i18n constructs when they are located after a ``{#`` / ``#}``-type comment on the same line. E.g.: .. code-block:: html+django {# A comment #}{% trans "This literal was incorrectly ignored. Not anymore" %} Location of translator comments ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ :ref:`translator-comments-in-templates` specified using ``{#`` / ``#}`` need to be at the end of a line. If they are not, the comments are ignored and :djadmin:`makemessages` will generate a warning. For example: .. code-block:: html+django {# Translators: This is ignored #}{% trans "Translate me" %} {{ title }}{# Translators: Extracted and associated with 'Welcome' below #}

{% trans "Welcome" %}

Quoting in :func:`~django.core.urlresolvers.reverse` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When reversing URLs, Django didn't apply :func:`~django.utils.http.urlquote` to arguments before interpolating them in URL patterns. This bug is fixed in Django 1.6. If you worked around this bug by applying URL quoting before passing arguments to :func:`~django.core.urlresolvers.reverse`, this may result in double-quoting. If this happens, simply remove the URL quoting from your code. Storage of IP addresses in the comments app ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The :doc:`comments ` app now uses a ``GenericIPAddressField`` for storing commenters' IP addresses, to support comments submitted from IPv6 addresses. Until now, it stored them in an ``IPAddressField``, which is only meant to support IPv4. When saving a comment made from an IPv6 address, the address would be silently truncated on MySQL databases, and raise an exception on Oracle. You will need to change the column type in your database to benefit from this change. For MySQL, execute this query on your project's database: .. code-block:: sql ALTER TABLE django_comments MODIFY ip_address VARCHAR(39); For Oracle, execute this query: .. code-block:: sql ALTER TABLE DJANGO_COMMENTS MODIFY (ip_address VARCHAR2(39)); If you do not apply this change, the behavior is unchanged: on MySQL, IPv6 addresses are silently truncated; on Oracle, an exception is generated. No database change is needed for SQLite or PostgreSQL databases. Percent literals in ``cursor.execute`` queries ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When you are running raw SQL queries through the :ref:`cursor.execute ` method, the rule about doubling percent literals (``%``) inside the query has been unified. Past behavior depended on the database backend. Now, across all backends, you only need to double literal percent characters if you are also providing replacement parameters. For example:: # No parameters, no percent doubling cursor.execute("SELECT foo FROM bar WHERE baz = '30%'") # Parameters passed, non-placeholders have to be doubled cursor.execute("SELECT foo FROM bar WHERE baz = '30%%' and id = %s", [self.id]) ``SQLite`` users need to check and update such queries. .. _m2m-help_text: Help text of model form fields for ManyToManyField fields ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HTML rendering of model form fields corresponding to :class:`~django.db.models.ManyToManyField` ORM model fields used to get the hard-coded sentence *Hold down "Control", or "Command" on a Mac, to select more than one.* (or its translation to the active locale) imposed as the help legend shown along them if neither :attr:`model ` nor :attr:`form ` ``help_text`` attribute was specified by the user (or appended to, if ``help_text`` was provided.) This happened always, possibly even with form fields implementing user interactions that don't involve a keyboard and/or a mouse and was handled at the model field layer. Starting with Django 1.6 this doesn't happen anymore. The change can affect you in a backward incompatible way if you employ custom model form fields and/or widgets for ``ManyToManyField`` model fields whose UIs do rely on the automatic provision of the mentioned hard-coded sentence. These form field implementations need to adapt to the new scenario by providing their own handling of the ``help_text`` attribute. Applications that use Django :doc:`model form ` facilities together with Django built-in form :doc:`fields ` and :doc:`widgets ` aren't affected but need to be aware of what's described in :ref:`m2m-help_text-deprecation` below. This is because, as an ad-hoc temporary backward-compatibility provision, the described non-standard behavior has been preserved but moved to the model form field layer and occurs only when the associated widget is :class:`~django.forms.SelectMultiple` or selected subclasses. QuerySet iteration ~~~~~~~~~~~~~~~~~~ The ``QuerySet`` iteration was changed to immediately convert all fetched rows to ``Model`` objects. In Django 1.5 and earlier the fetched rows were converted to ``Model`` objects in chunks of 100. Existing code will work, but the amount of rows converted to objects might change in certain use cases. Such usages include partially looping over a queryset or any usage which ends up doing ``__bool__`` or ``__contains__``. Notably most database backends did fetch all the rows in one go already in 1.5. It is still possible to convert the fetched rows to ``Model`` objects lazily by using the :meth:`~django.db.models.query.QuerySet.iterator()` method. :meth:`BoundField.label_tag` now includes the form's :attr:`~django.forms.Form.label_suffix` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This is consistent with how methods like :meth:`Form.as_p` and :meth:`Form.as_ul` render labels. If you manually render ``label_tag`` in your templates: .. code-block:: html+django {{ form.my_field.label_tag }}: {{ form.my_field }} you'll want to remove the colon (or whatever other separator you may be using) to avoid duplicating it when upgrading to Django 1.6. The following template in Django 1.6 will render identically to the above template in Django 1.5, except that the colon will appear inside the ``