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Code Issues 25 Releases Wiki Activity

Refs #32674 -- Noted that auto-created through table PKs cannot be automatically migrated.

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Carlton Gibson 2021-04-29 10:59:14 +02:00
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25
docs/ref/settings.txt
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@ -1260,6 +1260,31 @@ Default: ``'``:class:`django.db.models.AutoField`\ ``'``
Default primary key field type to use for models that don't have a field with
:attr:`primary_key=True <django.db.models.Field.primary_key>`.
.. admonition:: Migrating auto-created through tables
The value of ``DEFAULT_AUTO_FIELD`` will be respected when creating new
auto-created through tables for many-to-many relationships.
Unfortunately, the primary keys of existing auto-created through tables
cannot currently be updated by the migrations framework.
This means that if you switch the value of ``DEFAULT_AUTO_FIELD`` and then
generate migrations, the primary keys of the related models will be
updated, as will the foreign keys from the through table, but the primary
key of the auto-created through table will not be migrated.
In order to address this, you should add a
:class:`~django.db.migrations.operations.RunSQL` operation to your
migrations to perform the required ``ALTER TABLE`` step. You can check the
existing table name through ``sqlmigrate``, ``dbshell``, or with the
field’s ``remote_field.through._meta.db_table`` property.
Explicitly defined through models are already handled by the migrations
system.
Allowing automatic migrations for the primary key of existing auto-created
through tables :ticket:`may be implemented at a later date <32674>`.
.. setting:: DEFAULT_CHARSET
``DEFAULT_CHARSET``

5
docs/releases/3.2.txt
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@ -95,6 +95,11 @@ or on a per-model basis::
In anticipation of the changing default, a system check will provide a warning
if you do not have an explicit setting for :setting:`DEFAULT_AUTO_FIELD`.
When changing the value of :setting:`DEFAULT_AUTO_FIELD`, migrations for the
primary key of existing auto-created through tables cannot be generated
currently. See the :setting:`DEFAULT_AUTO_FIELD` docs for details on migrating
such tables.
.. _new_functional_indexes:
Functional indexes