Django 2.0 release notes¶
December 2, 2017
Welcome to Django 2.0!
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 1.11 or earlier. We’ve dropped some features that have reached the end of their deprecation cycle, and we’ve begun the deprecation process for some features.
This release starts Django’s use of a loose form of semantic versioning, but there aren’t any major backwards incompatible changes that might be expected of a 2.0 release. Upgrading should be a similar amount of effort as past feature releases.
See the Upgrading Django to a newer version guide if you’re updating an existing project.
Python compatibility¶
Django 2.0 supports Python 3.4, 3.5, 3.6, and 3.7. We highly recommend and only officially support the latest release of each series.
The Django 1.11.x series is the last to support Python 2.7.
Django 2.0 will be the last release series to support Python 3.4. If you plan a deployment of Python 3.4 beyond the end-of-life for Django 2.0 (April 2019), stick with Django 1.11 LTS (supported until April 2020) instead. Note, however, that the end-of-life for Python 3.4 is March 2019.
Third-party library support for older version of Django¶
Following the release of Django 2.0, we suggest that third-party app authors
drop support for all versions of Django prior to 1.11. At that time, you should
be able to run your package’s tests using python -Wd
so that deprecation
warnings do appear. After making the deprecation warning fixes, your app should
be compatible with Django 2.0.
What’s new in Django 2.0¶
Simplified URL routing syntax¶
The new django.urls.path()
function allows a simpler, more readable URL
routing syntax. For example, this example from previous Django releases:
url(r'^articles/(?P<year>[0-9]{4})/$', views.year_archive),
could be written as:
path('articles/<int:year>/', views.year_archive),
The new syntax supports type coercion of URL parameters. In the example, the
view will receive the year
keyword argument as an integer rather than as
a string. Also, the URLs that will match are slightly less constrained in the
rewritten example. For example, the year 10000 will now match since the year
integers aren’t constrained to be exactly four digits long as they are in the
regular expression.
The django.conf.urls.url()
function from previous versions is now available
as django.urls.re_path()
. The old location remains for backwards
compatibility, without an imminent deprecation. The old
django.conf.urls.include()
function is now importable from django.urls
so you can use from django.urls import include, path, re_path
in your
URLconfs.
The URL dispatcher document is rewritten to feature the new syntax and provide more details.
Mobile-friendly contrib.admin
¶
The admin is now responsive and supports all major mobile devices. Older browsers may experience varying levels of graceful degradation.
Window expressions¶
The new Window
expression allows
adding an OVER
clause to querysets. You can use window functions and aggregate functions in
the expression.
Minor features¶
django.contrib.admin
¶
- The new
ModelAdmin.autocomplete_fields
attribute andModelAdmin.get_autocomplete_fields()
method allow using a Select2 search widget forForeignKey
andManyToManyField
.
django.contrib.auth
¶
- The default iteration count for the PBKDF2 password hasher is increased from 36,000 to 100,000.
django.contrib.gis
¶
- Added MySQL support for the
AsGeoJSON
function,GeoHash
function,IsValid
function,isvalid
lookup, and distance lookups. - Added the
Azimuth
andLineLocatePoint
functions, supported on PostGIS and SpatiaLite. - Any
GEOSGeometry
imported from GeoJSON now has its SRID set. - Added the
OSMWidget.default_zoom
attribute to customize the map’s default zoom level. - Made metadata readable and editable on rasters through the
metadata
,info
, andmetadata
attributes. - Allowed passing driver-specific creation options to
GDALRaster
objects usingpapsz_options
. - Allowed creating
GDALRaster
objects in GDAL’s internal virtual filesystem. Rasters can now be created from and converted to binary data in-memory. - The new
GDALBand.color_interp()
method returns the color interpretation for the band.
django.contrib.postgres
¶
- The new
distinct
argument forArrayAgg
determines if concatenated values will be distinct. - The new
RandomUUID
database function returns a version 4 UUID. It requires use of PostgreSQL’spgcrypto
extension which can be activated using the newCryptoExtension
migration operation. django.contrib.postgres.indexes.GinIndex
now supports thefastupdate
andgin_pending_list_limit
parameters.- The new
GistIndex
class allows creatingGiST
indexes in the database. The newBtreeGistExtension
migration operation installs thebtree_gist
extension to add support for operator classes that aren’t built-in. inspectdb
can now introspectJSONField
and variousRangeField
s (django.contrib.postgres
must be inINSTALLED_APPS
).
django.contrib.sitemaps
¶
- Added the
protocol
keyword argument to theGenericSitemap
constructor.
Cache¶
cache.set_many()
now returns a list of keys that failed to be inserted. For the built-in backends, failed inserts can only happen on memcached.
File Storage¶
File.open()
can be used as a context manager, e.g.with file.open() as f:
.
Forms¶
- The new
date_attrs
andtime_attrs
arguments forSplitDateTimeWidget
andSplitHiddenDateTimeWidget
allow specifying different HTML attributes for theDateInput
andTimeInput
(or hidden) subwidgets. - The new
Form.errors.get_json_data()
method returns form errors as a dictionary suitable for including in a JSON response.
Generic Views¶
- The new
ContextMixin.extra_context
attribute allows adding context inView.as_view()
.
Management Commands¶
inspectdb
now translates MySQL’s unsigned integer columns toPositiveIntegerField
orPositiveSmallIntegerField
.- The new
makemessages --add-location
option controls the comment format in PO files. loaddata
can now read from stdin.- The new
diffsettings --output
option allows formatting the output in a unified diff format. - On Oracle,
inspectdb
can now introspectAutoField
if the column is created as an identity column. - On MySQL,
dbshell
now supports client-side TLS certificates.
Migrations¶
- The new
squashmigrations --squashed-name
option allows naming the squashed migration.
Models¶
- The new
StrIndex
database function finds the starting index of a string inside another string. - On Oracle,
AutoField
andBigAutoField
are now created as identity columns. - The new
chunk_size
parameter ofQuerySet.iterator()
controls the number of rows fetched by the Python database client when streaming results from the database. For databases that don’t support server-side cursors, it controls the number of results Django fetches from the database adapter. QuerySet.earliest()
,QuerySet.latest()
, andMeta.get_latest_by
now allow ordering by several fields.- Added the
ExtractQuarter
function to extract the quarter fromDateField
andDateTimeField
, and exposed it through thequarter
lookup. - Added the
TruncQuarter
function to truncateDateField
andDateTimeField
to the first day of a quarter. - Added the
db_tablespace
parameter to class-based indexes. - If the database supports a native duration field (Oracle and PostgreSQL),
Extract
now works withDurationField
. - Added the
of
argument toQuerySet.select_for_update()
, supported on PostgreSQL and Oracle, to lock only rows from specific tables rather than all selected tables. It may be helpful particularly whenselect_for_update()
is used in conjunction withselect_related()
. - The new
field_name
parameter ofQuerySet.in_bulk()
allows fetching results based on any unique model field. CursorWrapper.callproc()
now takes an optional dictionary of keyword parameters, if the backend supports this feature. Of Django’s built-in backends, only Oracle supports it.- The new
connection.execute_wrapper()
method allows installing wrappers around execution of database queries. - The new
filter
argument for built-in aggregates allows adding different conditionals to multiple aggregations over the same fields or relations. - Added support for expressions in
Meta.ordering
. - The new
named
parameter ofQuerySet.values_list()
allows fetching results as named tuples. - The new
FilteredRelation
class allows adding anON
clause to querysets.
Pagination¶
- Added
Paginator.get_page()
to provide the documented pattern of handling invalid page numbers.
Templates¶
- To increase the usefulness of
Engine.get_default()
in third-party apps, it now returns the first engine if multipleDjangoTemplates
engines are configured inTEMPLATES
rather than raisingImproperlyConfigured
. - Custom template tags may now accept keyword-only arguments.
Tests¶
- Added threading support to
LiveServerTestCase
. - Added settings that allow customizing the test tablespace parameters for
Oracle:
DATAFILE_SIZE
,DATAFILE_TMP_SIZE
,DATAFILE_EXTSIZE
, andDATAFILE_TMP_EXTSIZE
.
Validators¶
- The new
ProhibitNullCharactersValidator
disallows the null character in the input of theCharField
form field and its subclasses. Null character input was observed from vulnerability scanning tools. Most databases silently discard null characters, but psycopg2 2.7+ raises an exception when trying to save a null character to a char/text field with PostgreSQL.
Backwards incompatible changes in 2.0¶
Removed support for bytestrings in some places¶
To support native Python 2 strings, older Django versions had to accept both
bytestrings and unicode strings. Now that Python 2 support is dropped,
bytestrings should only be encountered around input/output boundaries (handling
of binary fields or HTTP streams, for example). You might have to update your
code to limit bytestring usage to a minimum, as Django no longer accepts
bytestrings in certain code paths. Python’s -b
option may help detect
that mistake in your code.
For example, reverse()
now uses str()
instead of force_text()
to
coerce the args
and kwargs
it receives, prior to their placement in
the URL. For bytestrings, this creates a string with an undesired b
prefix
as well as additional quotes (str(b'foo')
is "b'foo'"
). To adapt, call
decode()
on the bytestring before passing it to reverse()
.
Database backend API¶
This section describes changes that may be needed in third-party database backends.
- The
DatabaseOperations.datetime_cast_date_sql()
,datetime_cast_time_sql()
,datetime_trunc_sql()
,datetime_extract_sql()
, anddate_interval_sql()
methods now return only the SQL to perform the operation instead of SQL and a list of parameters. - Third-party database backends should add a
DatabaseWrapper.display_name
attribute with the name of the database that your backend works with. Django may use it in various messages, such as in system checks. - The first argument of
SchemaEditor._alter_column_type_sql()
is nowmodel
rather thantable
. - The first argument of
SchemaEditor._create_index_name()
is nowtable_name
rather thanmodel
. - To enable
FOR UPDATE OF
support, setDatabaseFeatures.has_select_for_update_of = True
. If the database requires that the arguments toOF
be columns rather than tables, setDatabaseFeatures.select_for_update_of_column = True
. - To enable support for
Window
expressions, setDatabaseFeatures.supports_over_clause
toTrue
. You may need to customize theDatabaseOperations.window_start_rows_start_end()
and/orwindow_start_range_start_end()
methods. - Third-party database backends should add a
DatabaseOperations.cast_char_field_without_max_length
attribute with the database data type that will be used in theCast
function for aCharField
if themax_length
argument isn’t provided. - The first argument of
DatabaseCreation._clone_test_db()
andget_test_db_clone_settings()
is nowsuffix
rather thannumber
(in case you want to rename the signatures in your backend for consistency).django.test
also now passes those values as strings rather than as integers. - Third-party database backends should add a
DatabaseIntrospection.get_sequences()
method based on the stub inBaseDatabaseIntrospection
.
Dropped support for Oracle 11.2¶
The end of upstream support for Oracle 11.2 is Dec. 2020. Django 1.11 will be supported until April 2020 which almost reaches this date. Django 2.0 officially supports Oracle 12.1+.
Default MySQL isolation level is read committed¶
MySQL’s default isolation level, repeatable read, may cause data loss in
typical Django usage. To prevent that and for consistency with other databases,
the default isolation level is now read committed. You can use the
DATABASES
setting to use a different isolation level, if needed.
AbstractUser.last_name
max_length
increased to 150¶
A migration for django.contrib.auth.models.User.last_name
is included.
If you have a custom user model inheriting from AbstractUser
, you’ll need
to generate and apply a database migration for your user model.
If you want to preserve the 30 character limit for last names, use a custom form:
from django.contrib.auth.forms import UserChangeForm
class MyUserChangeForm(UserChangeForm):
last_name = forms.CharField(max_length=30, required=False)
If you wish to keep this restriction in the admin when editing users, set
UserAdmin.form
to use this form:
from django.contrib.auth.admin import UserAdmin
from django.contrib.auth.models import User
class MyUserAdmin(UserAdmin):
form = MyUserChangeForm
admin.site.unregister(User)
admin.site.register(User, MyUserAdmin)
QuerySet.reverse()
and last()
are prohibited after slicing¶
Calling QuerySet.reverse()
or last()
on a sliced queryset leads to
unexpected results due to the slice being applied after reordering. This is
now prohibited, e.g.:
>>> Model.objects.all()[:2].reverse()
Traceback (most recent call last):
...
TypeError: Cannot reverse a query once a slice has been taken.
Form fields no longer accept optional arguments as positional arguments¶
To help prevent runtime errors due to incorrect ordering of form field arguments, optional arguments of built-in form fields are no longer accepted as positional arguments. For example:
forms.IntegerField(25, 10)
raises an exception and should be replaced with:
forms.IntegerField(max_value=25, min_value=10)
call_command()
validates the options it receives¶
call_command()
now validates that the argument parser of the command being
called defines all of the options passed to call_command()
.
For custom management commands that use options not created using
parser.add_argument()
, add a stealth_options
attribute on the command:
class MyCommand(BaseCommand):
stealth_options = ('option_name', ...)
Indexes no longer accept positional arguments¶
For example:
models.Index(['headline', '-pub_date'], 'index_name')
raises an exception and should be replaced with:
models.Index(fields=['headline', '-pub_date'], name='index_name')
Foreign key constraints are now enabled on SQLite¶
This will appear as a backwards-incompatible change (IntegrityError:
FOREIGN KEY constraint failed
) if attempting to save an existing model
instance that’s violating a foreign key constraint.
Foreign keys are now created with DEFERRABLE INITIALLY DEFERRED
instead of
DEFERRABLE IMMEDIATE
. Thus, tables may need to be rebuilt to recreate
foreign keys with the new definition, particularly if you’re using a pattern
like this:
from django.db import transaction
with transaction.atomic():
Book.objects.create(author_id=1)
Author.objects.create(id=1)
If you don’t recreate the foreign key as DEFERRED
, the first create()
would fail now that foreign key constraints are enforced.
Backup your database first! After upgrading to Django 2.0, you can then rebuild tables using a script similar to this:
from django.apps import apps
from django.db import connection
for app in apps.get_app_configs():
for model in app.get_models(include_auto_created=True):
if model._meta.managed and not (model._meta.proxy or model._meta.swapped):
for base in model.__bases__:
if hasattr(base, '_meta'):
base._meta.local_many_to_many = []
model._meta.local_many_to_many = []
with connection.schema_editor() as editor:
editor._remake_table(model)
This script hasn’t received extensive testing and needs adaption for various cases such as multiple databases. Feel free to contribute improvements.
In addition, because of a table alteration limitation of SQLite, it’s prohibited
to perform RenameModel
and
RenameField
operations on models or
fields referenced by other models in a transaction. In order to allow migrations
containing these operations to be applied, you must set the
Migration.atomic
attribute to False
.
Miscellaneous¶
The
SessionAuthenticationMiddleware
class is removed. It provided no functionality since session authentication is unconditionally enabled in Django 1.10.The default HTTP error handlers (
handler404
, etc.) are now callables instead of dotted Python path strings. Django favors callable references since they provide better performance and debugging experience.RedirectView
no longer silencesNoReverseMatch
if thepattern_name
doesn’t exist.When
USE_L10N
is off,FloatField
andDecimalField
now respectDECIMAL_SEPARATOR
andTHOUSAND_SEPARATOR
during validation. For example, with the settings:USE_L10N = False USE_THOUSAND_SEPARATOR = True DECIMAL_SEPARATOR = ',' THOUSAND_SEPARATOR = '.'
an input of
"1.345"
is now converted to1345
instead of1.345
.Subclasses of
AbstractBaseUser
are no longer required to implementget_short_name()
andget_full_name()
. (The base implementations that raiseNotImplementedError
are removed.)django.contrib.admin
uses these methods if implemented but doesn’t require them. Third-party apps that use these methods may want to adopt a similar approach.The
FIRST_DAY_OF_WEEK
andNUMBER_GROUPING
format settings are now kept as integers in JavaScript and JSON i18n view outputs.assertNumQueries()
now ignores connection configuration queries. Previously, if a test opened a new database connection, those queries could be included as part of theassertNumQueries()
count.The default size of the Oracle test tablespace is increased from 20M to 50M and the default autoextend size is increased from 10M to 25M.
To improve performance when streaming large result sets from the database,
QuerySet.iterator()
now fetches 2000 rows at a time instead of 100. The old behavior can be restored using thechunk_size
parameter. For example:Book.objects.iterator(chunk_size=100)
Providing unknown package names in the
packages
argument of theJavaScriptCatalog
view now raisesValueError
instead of passing silently.A model instance’s primary key now appears in the default
Model.__str__()
method, e.g.Question object (1)
.makemigrations
now detects changes to the model fieldlimit_choices_to
option. Add this to your existing migrations or accept an auto-generated migration for fields that use it.Performing queries that require automatic spatial transformations now raises
NotImplementedError
on MySQL instead of silently using non-transformed geometries.django.core.exceptions.DjangoRuntimeWarning
is removed. It was only used in the cache backend as an intermediate class inCacheKeyWarning
’s inheritance ofRuntimeWarning
.Renamed
BaseExpression._output_field
tooutput_field
. You may need to update custom expressions.In older versions, forms and formsets combine their
Media
with widgetMedia
by concatenating the two. The combining now tries to preserve the relative order of elements in each list.MediaOrderConflictWarning
is issued if the order can’t be preserved.django.contrib.gis.gdal.OGRException
is removed. It’s been an alias forGDALException
since Django 1.8.Support for GEOS 3.3.x is dropped.
The way data is selected for
GeometryField
is changed to improve performance, and in raw SQL queries, those fields must now be wrapped inconnection.ops.select
. See the Raw queries note in the GIS tutorial for an example.
Features deprecated in 2.0¶
context
argument of Field.from_db_value()
and Expression.convert_value()
¶
The context
argument of Field.from_db_value()
and
Expression.convert_value()
is unused as it’s always an empty dictionary.
The signature of both methods is now:
(self, value, expression, connection)
instead of:
(self, value, expression, connection, context)
Support for the old signature in custom fields and expressions remains until Django 3.0.
Miscellaneous¶
- The
django.db.backends.postgresql_psycopg2
module is deprecated in favor ofdjango.db.backends.postgresql
. It’s been an alias since Django 1.9. This only affects code that imports from the module directly. TheDATABASES
setting can still use'django.db.backends.postgresql_psycopg2'
, though you can simplify that by using the'django.db.backends.postgresql'
name added in Django 1.9. django.shortcuts.render_to_response()
is deprecated in favor ofdjango.shortcuts.render()
.render()
takes the same arguments except that it also requires arequest
.- The
DEFAULT_CONTENT_TYPE
setting is deprecated. It doesn’t interact well with third-party apps and is obsolete since HTML5 has mostly superseded XHTML. HttpRequest.xreadlines()
is deprecated in favor of iterating over the request.- The
field_name
keyword argument toQuerySet.earliest()
andQuerySet.latest()
is deprecated in favor of passing the field names as arguments. Write.earliest('pub_date')
instead of.earliest(field_name='pub_date')
.
Features removed in 2.0¶
These features have reached the end of their deprecation cycle and are removed in Django 2.0.
See Features deprecated in 1.9 for details on these changes, including how to remove usage of these features.
- The
weak
argument todjango.dispatch.signals.Signal.disconnect()
is removed. django.db.backends.base.BaseDatabaseOperations.check_aggregate_support()
is removed.- The
django.forms.extras
package is removed. - The
assignment_tag
helper is removed. - The
host
argument toSimpleTestCase.assertsRedirects()
is removed. The compatibility layer which allows absolute URLs to be considered equal to relative ones when the path is identical is also removed. Field.rel
andField.remote_field.to
are removed.- The
on_delete
argument forForeignKey
andOneToOneField
is now required in models and migrations. Consider squashing migrations so that you have fewer of them to update. django.db.models.fields.add_lazy_relation()
is removed.- When time zone support is enabled, database backends that don’t support time
zones no longer convert aware datetimes to naive values in UTC anymore when
such values are passed as parameters to SQL queries executed outside of the
ORM, e.g. with
cursor.execute()
. django.contrib.auth.tests.utils.skipIfCustomUser()
is removed.- The
GeoManager
andGeoQuerySet
classes are removed. - The
django.contrib.gis.geoip
module is removed. - The
supports_recursion
check for template loaders is removed from:django.template.engine.Engine.find_template()
django.template.loader_tags.ExtendsNode.find_template()
django.template.loaders.base.Loader.supports_recursion()
django.template.loaders.cached.Loader.supports_recursion()
- The
load_template
andload_template_sources
template loader methods are removed. - The
template_dirs
argument for template loaders is removed:django.template.loaders.base.Loader.get_template()
django.template.loaders.cached.Loader.cache_key()
django.template.loaders.cached.Loader.get_template()
django.template.loaders.cached.Loader.get_template_sources()
django.template.loaders.filesystem.Loader.get_template_sources()
django.template.loaders.base.Loader.__call__()
is removed.- Support for custom error views that don’t accept an
exception
parameter is removed. - The
mime_type
attribute ofdjango.utils.feedgenerator.Atom1Feed
anddjango.utils.feedgenerator.RssFeed
is removed. - The
app_name
argument toinclude()
is removed. - Support for passing a 3-tuple (including
admin.site.urls
) as the first argument toinclude()
is removed. - Support for setting a URL instance namespace without an application namespace is removed.
Field._get_val_from_obj()
is removed.django.template.loaders.eggs.Loader
is removed.- The
current_app
parameter to thecontrib.auth
function-based views is removed. - The
callable_obj
keyword argument toSimpleTestCase.assertRaisesMessage()
is removed. - Support for the
allow_tags
attribute onModelAdmin
methods is removed. - The
enclosure
keyword argument toSyndicationFeed.add_item()
is removed. - The
django.template.loader.LoaderOrigin
anddjango.template.base.StringOrigin
aliases fordjango.template.base.Origin
are removed.
See Features deprecated in 1.10 for details on these changes.
- The
makemigrations --exit
option is removed. - Support for direct assignment to a reverse foreign key or many-to-many relation is removed.
- The
get_srid()
andset_srid()
methods ofdjango.contrib.gis.geos.GEOSGeometry
are removed. - The
get_x()
,set_x()
,get_y()
,set_y()
,get_z()
, andset_z()
methods ofdjango.contrib.gis.geos.Point
are removed. - The
get_coords()
andset_coords()
methods ofdjango.contrib.gis.geos.Point
are removed. - The
cascaded_union
property ofdjango.contrib.gis.geos.MultiPolygon
is removed. django.utils.functional.allow_lazy()
is removed.- The
shell --plain
option is removed. - The
django.core.urlresolvers
module is removed in favor of its new location,django.urls
. CommaSeparatedIntegerField
is removed, except for support in historical migrations.- The template
Context.has_key()
method is removed. - Support for the
django.core.files.storage.Storage.accessed_time()
,created_time()
, andmodified_time()
methods is removed. - Support for query lookups using the model name when
Meta.default_related_name
is set is removed. - The MySQL
__search
lookup is removed. - The shim for supporting custom related manager classes without a
_apply_rel_filters()
method is removed. - Using
User.is_authenticated()
andUser.is_anonymous()
as methods rather than properties is no longer supported. - The
Model._meta.virtual_fields
attribute is removed. - The keyword arguments
virtual_only
inField.contribute_to_class()
andvirtual
inModel._meta.add_field()
are removed. - The
javascript_catalog()
andjson_catalog()
views are removed. django.contrib.gis.utils.precision_wkt()
is removed.- In multi-table inheritance, implicit promotion of a
OneToOneField
to aparent_link
is removed. - Support for
Widget._format_value()
is removed. FileField
methodsget_directory_name()
andget_filename()
are removed.- The
mark_for_escaping()
function and the classes it uses:EscapeData
,EscapeBytes
,EscapeText
,EscapeString
, andEscapeUnicode
are removed. - The
escape
filter now usesdjango.utils.html.conditional_escape()
. Manager.use_for_related_fields
is removed.- Model
Manager
inheritance follows MRO inheritance rules. The requirement to useMeta.manager_inheritance_from_future
to opt-in to the behavior is removed. - Support for old-style middleware using
settings.MIDDLEWARE_CLASSES
is removed.