From 65effbdb101714ac98b3f143eaccadd8e4f08361 Mon Sep 17 00:00:00 2001 From: sarahboyce Date: Fri, 1 Apr 2022 20:21:43 +0200 Subject: Fixed #33471 -- Made AlterField operation a noop when changing "choices". This also allows customizing attributes of fields that don't affect a column definition. --- docs/howto/custom-model-fields.txt | 20 ++++++++++++++++++++ docs/releases/4.1.txt | 4 ++++ 2 files changed, 24 insertions(+) (limited to 'docs') diff --git a/docs/howto/custom-model-fields.txt b/docs/howto/custom-model-fields.txt index 2dedf05a11..c4621c8500 100644 --- a/docs/howto/custom-model-fields.txt +++ b/docs/howto/custom-model-fields.txt @@ -314,6 +314,26 @@ reconstructing the field:: new_instance = MyField(*args, **kwargs) self.assertEqual(my_field_instance.some_attribute, new_instance.some_attribute) +.. _custom-field-non_db_attrs: + +Field attributes not affecting database column definition +--------------------------------------------------------- + +.. versionadded:: 4.1 + +You can override ``Field.non_db_attrs`` to customize attributes of a field that +don't affect a column definition. It's used during model migrations to detect +no-op ``AlterField`` operations. + +For example:: + + class CommaSepField(models.Field): + + @property + def non_db_attrs(self): + return super().non_db_attrs + ("separator",) + + Changing a custom field's base class ------------------------------------ diff --git a/docs/releases/4.1.txt b/docs/releases/4.1.txt index 4413fdfc9a..d83da638fc 100644 --- a/docs/releases/4.1.txt +++ b/docs/releases/4.1.txt @@ -288,6 +288,10 @@ Models 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 :ref:`Field.non_db_attrs ` attribute + allows customizing attributes of fields that don't affect a column + definition. + Requests and Responses ~~~~~~~~~~~~~~~~~~~~~~ -- cgit v1.3