#22421: Loading fixtures with one-to-one inheritance and M2M with natural keys
fails since 1.7 Beta
-------------------------------------+-------------------------------------
Reporter: stanislas.guerra@… | Owner: nobody
Type: Bug | Status: new
Component: Core | Version: master
(Serialization) | Resolution:
Severity: Normal | Triage Stage:
Keywords: | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by stanislas.guerra@…):
* needs_better_patch: => 0
* needs_docs: => 0
* needs_tests: => 0
Comment:
Looks like it came from this commit in
''django/db/models/fields/related.py#ForeignObject.get_instance_value_for_fields(instance,
fields)'' :
https://github.com/django/django/commit/244e2b71f512605f3d0a8e1ba4c9d6b538acf69d#diff-301
Which is related to the ticket #20820
{{{
- ret.append(instance.pk)
- else:
- ret.append(getattr(instance, field.attname))
+ possible_parent_link =
opts.get_ancestor_link(field.model)
+ if not possible_parent_link or
possible_parent_link.primary_key:
+ ret.append(instance.pk)
+ continue
+ ret.append(getattr(instance, field.attname))
return tuple(ret)
}}}
And especially the last line: `ret.append(getattr(instance,
field.attname))` (`<assistant obj>.id` in that case) which add a `None` to
the returned Tuple raising an Exception in `create_many_related_manager()`
:
{{{
self.related_val =
source_field.get_foreign_related_value(instance)
if None in self.related_val:
raise ValueError('"%r" needs to have a value for field
"%s" before '
'this many-to-many relationship can be
used.' %
(instance, source_field_name))
}}}
Because the Assistant object has not been saved yet.
FYI, the fixture loading fails when trying to save the ''Assistant''
object (which is a one-to-one to ''User'') because of the M2M
''user_permissions'' relation.
Hope this helps.
--
Ticket URL: <https://code.djangoproject.com/ticket/22421#comment:1>
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