#26702: Document custom field subclass change requires new custom field class
--------------------------------------+--------------------
Reporter: baylee | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.9
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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Related to #26586
Can't alter a custom field to have a different base field type.
Documentation should be updated to reflect this and proposed solution.
Example before state:
{{{
class CustomCharField(models.CharField):
def foo(self):
pass
class Author(models.Model):
name = CustomCharField(max_length=255)
}}}
Example of what won't work:
{{{
class CustomCharField(models.TextField):
def foo(self):
pass
class Author(models.Model):
name = CustomCharField(max_length=255)
}}}
Example of what you should change to:
{{{
class CustomFieldMixin(object):
def foo(self):
pass
class CustomCharField(CustomFieldMixin, models.CharField):
pass
class CustomTextField(CustomFieldMixin, models.TextField):
pass
class Author(models.Model):
name = CustomTextField(max_length=255)
}}}
Should also include link to:
https://docs.djangoproject.com/en/1.9/topics/migrations/#considerations-
when-removing-model-fields to explain why user must keep old field
definition around.
--
Ticket URL: <https://code.djangoproject.com/ticket/26702>
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