# Documentazione Django 5.2.8

# Django 4.1 release notes

3 Agosto 2022

Welcome to Django 4.1!

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 4.0 or earlier. We’ve begun the deprecation process for some features.

See the Come aggiornare Django ad una nuova versione guide if you’re updating an existing project.

## Compatibilità con Python

Django 4.1 supports Python 3.8, 3.9, 3.10, and 3.11 (as of 4.1.3). We highly recommend and only officially support the latest release of each series.

## What’s new in Django 4.1

### Asynchronous handlers for class-based views

View subclasses may now define async HTTP method handlers:

    import asyncio
    from django.http import HttpResponse
    from django.views import View

    class AsyncView(View):
        async def get(self, request, *args, **kwargs):
            # Perform view logic using await.
            await asyncio.sleep(1)
            return HttpResponse("Hello async world!")

See Asynchronous class-based views for more details.

### Asynchronous ORM interface

`QuerySet` now provides an asynchronous interface for all data access operations. These are named as-per the existing synchronous operations but with an `a` prefix, for example `acreate()`, `aget()`, and so on.

The new interface allows you to write asynchronous code without needing to wrap ORM operations in `sync_to_async()`:

    async for author in Author.objects.filter(name__startswith="A"):
        book = await author.books.afirst()

Note that, at this stage, the underlying database operations remain synchronous, with contributions ongoing to push asynchronous support down into the SQL compiler, and integrate asynchronous database drivers. The new asynchronous queryset interface currently encapsulates the necessary `sync_to_async()` operations for you, and will allow your code to take advantage of developments in the ORM’s asynchronous support as it evolves.

See Asynchronous queries for details and limitations.

### Validation of Constraints

`Check`, `unique`, and `exclusion` constraints defined in the `Meta.constraints` option are now checked during model validation.

### Form rendering accessibility

In order to aid users with screen readers, and other assistive technology, new `<div>` based form templates are available from this release. These provide more accessible navigation than the older templates, and are able to correctly group related controls, such as radio-lists, into fieldsets.

The new templates are recommended, and will become the default form rendering style when outputting a form, like `{{ form }}` in a template, from Django 5.0.

In order to ease adopting the new output style, the default form and formset templates are now configurable at the project level via the `FORM_RENDERER` setting.

See the Forms section (below) for full details.

### `CSRF_COOKIE_MASKED` setting

The new `CSRF_COOKIE_MASKED` transitional setting allows specifying whether to mask the CSRF cookie.

`CsrfViewMiddleware` no longer masks the CSRF cookie like it does the CSRF token in the DOM. If you are upgrading multiple instances of the same project to Django 4.1, you should set `CSRF_COOKIE_MASKED` to `True` during the transition, in order to allow compatibility with the older versions of Django. Once the transition to 4.1 is complete you can stop overriding `CSRF_COOKIE_MASKED`.

This setting is deprecated as of this release and will be removed in Django 5.0.

### Minor features

#### `django.contrib.admin`

- The admin dark mode CSS variables are now applied in a separate stylesheet and template block.

- ModelAdmin List Filters providing custom `FieldListFilter` subclasses can now control the query string value separator when filtering for multiple values using the `__in` lookup.

- The admin `history view` is now paginated.

- Related widget wrappers now have a link to object’s change form.

- The `AdminSite.get_app_list()` method now allows changing the order of apps and models on the admin index page.

#### `django.contrib.auth`

- The default iteration count for the PBKDF2 password hasher is increased from 320,000 to 390,000.

- The `RemoteUserBackend.configure_user()` method now allows synchronizing user attributes with attributes in a remote system such as an LDAP directory.

#### `django.contrib.gis`

- The new `GEOSGeometry.make_valid()` method allows converting invalid geometries to valid ones.

- The new `clone` argument for `GEOSGeometry.normalize()` allows creating a normalized clone of the geometry.

#### `django.contrib.postgres`

- The new `BitXor()` aggregate function returns an `int` of the bitwise `XOR` of all non-null input values.

- `SpGistIndex` now supports covering indexes on PostgreSQL 14+.

- `ExclusionConstraint` now supports covering exclusion constraints using SP-GiST indexes on PostgreSQL 14+.

- The new `default_bounds` attribute of `DateTimeRangeField` and `DecimalRangeField` allows specifying bounds for list and tuple inputs.

- `ExclusionConstraint` now allows specifying operator classes with the `OpClass()` expression.

#### `django.contrib.sitemaps`

- The default sitemap index template `<sitemapindex>` now includes the `<lastmod>` timestamp where available, through the new `get_latest_lastmod()` method. Custom sitemap index templates should be updated for the adjusted context variables.

#### `django.contrib.staticfiles`

- `ManifestStaticFilesStorage` now replaces paths to CSS source map references with their hashed counterparts.

#### Database backends

- Third-party database backends can now specify the minimum required version of the database using the `DatabaseFeatures.minimum_database_version` attribute which is a tuple (e.g. `(10, 0)` means «10.0»). If a minimum version is specified, backends must also implement `DatabaseWrapper.get_database_version()`, which returns a tuple of the current database version. The backend’s `DatabaseWrapper.init_connection_state()` method must call `super()` in order for the check to run.

#### I Form

- The default template used to render forms when cast to a string, e.g. in templates as `{{ form }}`, is now configurable at the project-level by setting `form_template_name` on the class provided for `FORM_RENDERER`.

  `Form.template_name` is now a property deferring to the renderer, but may be overridden with a string value to specify the template name per-form class.

  Similarly, the default template used to render formsets can be specified via the matching `formset_template_name` renderer attribute.

- The new `div.html` form template, referencing `Form.template_name_div` attribute, and matching `Form.as_div()` method, render forms using HTML `<div>` elements.

  This new output style is recommended over the existing `as_table()`, `as_p()` and `as_ul()` styles, as the template implements `<fieldset>` and `<legend>` to group related inputs and is easier for screen reader users to navigate.

  The div-based output will become the default rendering style from Django 5.0.

- In order to smooth adoption of the new `<div>` output style, two transitional form renderer classes are available: `django.forms.renderers.DjangoDivFormRenderer` and `django.forms.renderers.Jinja2DivFormRenderer`, for the Django and Jinja2 template backends respectively.

  You can apply one of these via the `FORM_RENDERER` setting. For example:

      FORM_RENDERER = "django.forms.renderers.DjangoDivFormRenderer"

  Once the `<div>` output style is the default, from Django 5.0, these transitional renderers will be deprecated, for removal in Django 6.0. The `FORM_RENDERER` declaration can be removed at that time.

- If the new `<div>` output style is not appropriate for your project, you should define a renderer subclass specifying `form_template_name` and `formset_template_name` for your required style, and set `FORM_RENDERER` accordingly.

  For example, for the `<p>` output style used by `as_p()`, you would define a form renderer setting `form_template_name` to `"django/forms/p.html"` and `formset_template_name` to `"django/forms/formsets/p.html"`.

- The new `legend_tag()` allows rendering field labels in `<legend>` tags via the new `tag` argument of `label_tag()`.

- The new `edit_only` argument for `modelformset_factory()` and `inlineformset_factory()` allows preventing new objects creation.

- The `js` and `css` class attributes of Media now allow using hashable objects, not only path strings, as long as those objects implement the `__html__()` method (typically when decorated with the `html_safe()` decorator).

- The new `BoundField.use_fieldset` and `Widget.use_fieldset` attributes help to identify widgets where its inputs should be grouped in a `<fieldset>` with a `<legend>`.

- The error_messages argument for `BaseFormSet` now allows customizing error messages for invalid number of forms by passing `'too_few_forms'` and `'too_many_forms'` keys.

- `IntegerField`, `FloatField`, and `DecimalField` now optionally accept a `step_size` argument. This is used to set the `step` HTML attribute, and is validated on form submission.

#### Internationalization

- The `i18n_patterns()` function now supports languages with both scripts and regions.

#### Management Commands

- `makemigrations --no-input` now logs default answers and reasons why migrations cannot be created.

- The new `makemigrations --scriptable` option diverts log output and input prompts to `stderr`, writing only paths of generated migration files to `stdout`.

- The new `migrate --prune` option allows deleting nonexistent migrations from the `django_migrations` table.

- Python files created by `startproject`, `startapp`, `optimizemigration`, `makemigrations`, and `squashmigrations` are now formatted using the `black` command if it is present on your `PATH`.

- The new `optimizemigration` command allows optimizing operations for a migration.

#### Migrations

- The new `RenameIndex` operation allows renaming indexes defined in the `Meta.indexes` or `index_together` options.

- The migrations autodetector now generates `RenameIndex` operations instead of `RemoveIndex` and `AddIndex`, when renaming indexes defined in the `Meta.indexes`.

- The migrations autodetector now generates `RenameIndex` operations instead of `AlterIndexTogether` and `AddIndex`, when moving indexes defined in the `Meta.index_together` to the `Meta.indexes`.

#### Modelli

- The `order_by` argument of the `Window` expression now accepts string references to fields and transforms.

- The new `CONN_HEALTH_CHECKS` setting allows enabling health checks for persistent database connections in order to reduce the number of failed requests, e.g. after database server restart.

- `QuerySet.bulk_create()` now supports updating fields when a row insertion fails uniqueness constraints. This is supported on MariaDB, MySQL, PostgreSQL, and SQLite 3.24+.

- `QuerySet.iterator()` now supports prefetching related objects as long as the `chunk_size` argument is provided. In older versions, no prefetching was done.

- `Q` objects and querysets can now be combined using `^` as the exclusive or (`XOR`) operator. `XOR` is natively supported on MariaDB and MySQL. For databases that do not support `XOR`, the query will be converted to an equivalent using `AND`, `OR`, and `NOT`.

- The new Field.non_db_attrs attribute allows customizing attributes of fields that don’t affect a column definition.

- On PostgreSQL, `AutoField`, `BigAutoField`, and `SmallAutoField` are now created as identity columns rather than serial columns with sequences.

#### Requests and Responses

- `HttpResponse.set_cookie()` now supports `timedelta` objects for the `max_age` argument.

#### Sicurezza

- The new `SECRET_KEY_FALLBACKS` setting allows providing a list of values for secret key rotation.

- The `SECURE_PROXY_SSL_HEADER` setting now supports a comma-separated list of protocols in the header value.

#### Signals

- The `pre_delete` and `post_delete` signals now dispatch the `origin` of the deletion.

#### Template

- The HTML `<script>` element `id` attribute is no longer required when wrapping the `json_script` template filter.

- The `cached template loader` is now enabled in development, when `DEBUG` is `True`, and `OPTIONS['loaders']` isn’t specified. You may specify `OPTIONS['loaders']` to override this, if necessary.

#### Tests

- The `DiscoverRunner` now supports running tests in parallel on macOS, Windows, and any other systems where the default `multiprocessing` start method is `spawn`.

- A nested atomic block marked as durable in `django.test.TestCase` now raises a `RuntimeError`, the same as outside of tests.

- `SimpleTestCase.assertFormError()` and `assertFormsetError()` now support passing a form/formset object directly.

#### URLs

- The new `ResolverMatch.captured_kwargs` attribute stores the captured keyword arguments, as parsed from the URL.

- The new `ResolverMatch.extra_kwargs` attribute stores the additional keyword arguments passed to the view function.

#### Utilities

- `SimpleLazyObject` now supports addition operations.

- `mark_safe()` now preserves lazy objects.

#### Validators

- The new `StepValueValidator` checks if a value is an integral multiple of a given step size. This new validator is used for the new `step_size` argument added to form fields representing numeric values.

## Backwards incompatible changes in 4.1

### Database backend API

This section describes changes that may be needed in third-party database backends.

- `BaseDatabaseFeatures.has_case_insensitive_like` is changed from `True` to `False` to reflect the behavior of most databases.

- `DatabaseIntrospection.get_key_columns()` is removed. Use `DatabaseIntrospection.get_relations()` instead.

- `DatabaseOperations.ignore_conflicts_suffix_sql()` method is replaced by `DatabaseOperations.on_conflict_suffix_sql()` that accepts the `fields`, `on_conflict`, `update_fields`, and `unique_fields` arguments.

- The `ignore_conflicts` argument of the `DatabaseOperations.insert_statement()` method is replaced by `on_conflict` that accepts `django.db.models.constants.OnConflict`.

- `DatabaseOperations._convert_field_to_tz()` is replaced by `DatabaseOperations._convert_sql_to_tz()` that accepts the `sql`, `params`, and `tzname` arguments.

- Several date and time methods on `DatabaseOperations` now take `sql` and `params` arguments instead of `field_name` and return 2-tuple containing some SQL and the parameters to be interpolated into that SQL. The changed methods have these new signatures:

  - `DatabaseOperations.date_extract_sql(lookup_type, sql, params)`

  - `DatabaseOperations.datetime_extract_sql(lookup_type, sql, params, tzname)`

  - `DatabaseOperations.time_extract_sql(lookup_type, sql, params)`

  - `DatabaseOperations.date_trunc_sql(lookup_type, sql, params, tzname=None)`

  - `DatabaseOperations.datetime_trunc_sql(self, lookup_type, sql, params, tzname)`

  - `DatabaseOperations.time_trunc_sql(lookup_type, sql, params, tzname=None)`

  - `DatabaseOperations.datetime_cast_date_sql(sql, params, tzname)`

  - `DatabaseOperations.datetime_cast_time_sql(sql, params, tzname)`

### `django.contrib.gis`

- Support for GDAL 2.1 is removed.

- Support for PostGIS 2.4 is removed.

### Dropped support for PostgreSQL 10

Upstream support for PostgreSQL 10 ends in November 2022. Django 4.1 supports PostgreSQL 11 and higher.

### Dropped support for MariaDB 10.2

Upstream support for MariaDB 10.2 ends in May 2022. Django 4.1 supports MariaDB 10.3 and higher.

### Admin changelist searches spanning multi-valued relationships changes

Admin changelist searches using multiple search terms are now applied in a single call to `filter()`, rather than in sequential `filter()` calls.

For multi-valued relationships, this means that rows from the related model must match all terms rather than any term. For example, if `search_fields` is set to `['child__name', 'child__age']`, and a user searches for `'Jamal 17'`, parent rows will be returned only if there is a relationship to some 17-year-old child named Jamal, rather than also returning parents who merely have a younger or older child named Jamal in addition to some other 17-year-old.

See the Spanning multi-valued relationships topic for more discussion of this difference. In Django 4.0 and earlier, `get_search_results()` followed the second example query, but this undocumented behavior led to queries with excessive joins.

### Reverse foreign key changes for unsaved model instances

In order to unify the behavior with many-to-many relations for unsaved model instances, a reverse foreign key now raises `ValueError` when calling `related managers` for unsaved objects.

### Miscellanea

- Related managers for `ForeignKey`, `ManyToManyField`, and `GenericRelation` are now cached on the `Model` instance to which they belong. This change was reverted in Django 4.1.2.

- `DiscoverRunner` now returns a non-zero error code for unexpected successes from tests marked with `unittest.expectedFailure()`.

- `CsrfViewMiddleware` no longer masks the CSRF cookie like it does the CSRF token in the DOM.

- `CsrfViewMiddleware` now uses `request.META['CSRF_COOKIE']` for storing the unmasked CSRF secret rather than a masked version. This is an undocumented, private API.

- The `ModelAdmin.actions` and `inlines` attributes now default to an empty tuple rather than an empty list to discourage unintended mutation.

- The `type="text/css"` attribute is no longer included in `<link>` tags for CSS form media.

- `formset:added` and `formset:removed` JavaScript events are now pure JavaScript events and don’t depend on jQuery. See Inline form events for more details on the change.

- The `exc_info` argument of the undocumented `django.utils.log.log_response()` function is replaced by `exception`.

- The `size` argument of the undocumented `django.views.static.was_modified_since()` function is removed.

- The admin log out UI now uses `POST` requests.

- The undocumented `InlineAdminFormSet.non_form_errors` property is replaced by the `non_form_errors()` method. This is consistent with `BaseFormSet`.

- As per above, the cached template loader is now enabled in development. You may specify `OPTIONS['loaders']` to override this, if necessary.

- The undocumented `django.contrib.auth.views.SuccessURLAllowedHostsMixin` mixin is replaced by `RedirectURLMixin`.

- `BaseConstraint` subclasses must implement `validate()` method to allow those constraints to be used for validation.

- The undocumented `URLResolver._is_callback()`, `URLResolver._callback_strs`, and `URLPattern.lookup_str()` are moved to `django.contrib.admindocs.utils`.

- The `Model.full_clean()` method now converts an `exclude` value to a `set`. It’s also preferable to pass an `exclude` value as a `set` to the `Model.clean_fields()`, `Model.full_clean()`, `Model.validate_unique()`, and `Model.validate_constraints()` methods.

- The minimum supported version of `asgiref` is increased from 3.4.1 to 3.5.2.

- Combined expressions no longer use the error-prone behavior of guessing `output_field` when argument types match. As a consequence, resolving an `output_field` for database functions and combined expressions may now crash with mixed types. You will need to explicitly set the `output_field` in such cases.

- The `makemessages` command no longer changes `.po` files when up to date. In older versions, `POT-Creation-Date` was always updated.

## Features deprecated in 4.1

### Log out via GET

Logging out via `GET` requests to the `built-in logout view` is deprecated. Use `POST` requests instead.

If you want to retain the user experience of an HTML link, you can use a form that is styled to appear as a link:

    <form id="logout-form" method="post" action="{% url 'admin:logout' %}">
      {% csrf_token %}
      <button type="submit">{% translate "Log out" %}</button>
    </form>

    #logout-form {
      display: inline;
    }
    #logout-form button {
      background: none;
      border: none;
      cursor: pointer;
      padding: 0;
      text-decoration: underline;
    }

### Miscellanea

- The context for sitemap index templates of a flat list of URLs is deprecated. Custom sitemap index templates should be updated for the adjusted context variables, expecting a list of objects with `location` and optional `lastmod` attributes.

- `CSRF_COOKIE_MASKED` transitional setting is deprecated.

- The `name` argument of `django.utils.functional.cached_property()` is deprecated as it’s unnecessary as of Python 3.6.

- The `opclasses` argument of `django.contrib.postgres.constraints.ExclusionConstraint` is deprecated in favor of using `OpClass()` in `ExclusionConstraint.expressions`. To use it, you need to add `'django.contrib.postgres'` in your `INSTALLED_APPS`.

  After making this change, `makemigrations` will generate a new migration with two operations: `RemoveConstraint` and `AddConstraint`. Since this change has no effect on the database schema, the `SeparateDatabaseAndState` operation can be used to only update the migration state without running any SQL. Move the generated operations into the `state_operations` argument of `SeparateDatabaseAndState`. For example:

      class Migration(migrations.Migration):
          ...

          operations = [
              migrations.SeparateDatabaseAndState(
                  database_operations=[],
                  state_operations=[
                      migrations.RemoveConstraint(...),
                      migrations.AddConstraint(...),
                  ],
              ),
          ]

- The undocumented ability to pass `errors=None` to `SimpleTestCase.assertFormError()` and `assertFormsetError()` is deprecated. Use `errors=[]` instead.

- `django.contrib.sessions.serializers.PickleSerializer` is deprecated due to the risk of remote code execution.

- The usage of `QuerySet.iterator()` on a queryset that prefetches related objects without providing the `chunk_size` argument is deprecated. In older versions, no prefetching was done. Providing a value for `chunk_size` signifies that the additional query per chunk needed to prefetch is desired.

- Passing unsaved model instances to related filters is deprecated. In Django 5.0, the exception will be raised.

- `created=True` is added to the signature of `RemoteUserBackend.configure_user()`. Support for `RemoteUserBackend` subclasses that do not accept this argument is deprecated.

- The `django.utils.timezone.utc` alias to `datetime.timezone.utc` is deprecated. Use `datetime.timezone.utc` directly.

- Passing a response object and a form/formset name to `SimpleTestCase.assertFormError()` and `assertFormsetError()` is deprecated. Use:

      assertFormError(response.context["form_name"], ...)
      assertFormsetError(response.context["formset_name"], ...)

  or pass the form/formset object directly instead.

- The undocumented `django.contrib.gis.admin.OpenLayersWidget` is deprecated.

- `django.contrib.auth.hashers.CryptPasswordHasher` is deprecated.

- The ability to pass `nulls_first=False` or `nulls_last=False` to `Expression.asc()` and `Expression.desc()` methods, and the `OrderBy` expression is deprecated. Use `None` instead.

- The `"django/forms/default.html"` and `"django/forms/formsets/default.html"` templates which are a proxy to the table-based templates are deprecated. Use the specific template instead.

- The undocumented `LogoutView.get_next_page()` method is renamed to `get_success_url()`.

## Features removed in 4.1

These features have reached the end of their deprecation cycle and are removed in Django 4.1.

See Features deprecated in 3.2 for details on these changes, including how to remove usage of these features.

- Support for assigning objects which don’t support creating deep copies with `copy.deepcopy()` to class attributes in `TestCase.setUpTestData()` is removed.

- Support for using a boolean value in `BaseCommand.requires_system_checks` is removed.

- The `whitelist` argument and `domain_whitelist` attribute of `django.core.validators.EmailValidator` are removed.

- The `default_app_config` application configuration variable is removed.

- `TransactionTestCase.assertQuerysetEqual()` no longer calls `repr()` on a queryset when compared to string values.

- The `django.core.cache.backends.memcached.MemcachedCache` backend is removed.

- Support for the pre-Django 3.2 format of messages used by `django.contrib.messages.storage.cookie.CookieStorage` is removed.