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Diffstat (limited to 'docs/howto')
| -rw-r--r-- | docs/howto/custom-model-fields.txt | 20 |
1 files changed, 20 insertions, 0 deletions
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 ------------------------------------ |