#29331: Model fields where the python attribute name does not match the db
column
are not saved
-------------------------------------+-------------------------------------
Reporter: Ben | Owner: nobody
Mathes |
Type: Bug | Status: new
Component: Database | Version: 2.0
layer (models, ORM) | Keywords: models,
Severity: Normal | deferred_field, save
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
When defining a model, if you rename a model's db column, django will
thing that model is deferred and will not {{{save()}}} it.
e.g.
{{{
class SomeModel(models.Model):
"""
a contrived model field where we want a "field" that is stored
in a "field" column, but we use @property getter/setters so
we name the SomeModel class's attribute as "_field".
"""
name = models.TextField(null=True)
_field = models.TextField(name="field")
@property
def field(self):
return self._field.upper()
@field.setter
def field(self, new_value):
self._field = new_value.lower()
}}}
With a renamed db column, {{{"_field"}} is in {{{self.__dict__}}}, but
{{{"field"}}} is not,
{{{
def get_deferred_fields(self):
"""
Return a set containing names of deferred fields for this instance.
"""
return {
f.attname for f in self._meta.concrete_fields
if f.attname not in self.__dict__
}
}}}
So {{{field}}} is not saved in {{{.save()}}}, because django _mistakenly_
thinks {{{"field"}}} is deferred, so it is ignored during {{{.save()}}}
{{{
#
https://github.com/django/django/blob/93331877c81c1c6641b163b97813268f483ede4b/django/db/models/base.py#L712
# ...
# elif not force_insert and deferred_fields and using ==
self._state.db:
# field_names = set()
# for field in self._meta.concrete_fields:
# if not field.primary_key and not hasattr(field, 'through'):
# field_names.add(field.attname)
# -> loaded_fields = field_names.difference(deferred_fields)
# if loaded_fields:
# update_fields = frozenset(loaded_fields)
#
# self.save_base(using=using, force_insert=force_insert,
# force_update=force_update,
update_fields=update_fields)
# ...
}}}
Reproduced in this github django repo:
https://github.com/benmathes/deferred_fields_bug
--
Ticket URL: <https://code.djangoproject.com/ticket/29331>
Django <https://code.djangoproject.com/>
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