id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
21612	queryset update ignores to_field on foreign keys	berndtj@…	nobody	"When issuing a batch update on a queryset, the to_field of the related model is ignored in some cases.  For instance, I am using a uuid field as a foreign key field (to_field).  When I try to update the relationship, the pk is used for in the foreign key column (<foreign_model>_id) instead of the uuid.  For example given a queryset of BracketVolumeTemplates which have a parent field which refers to a BracketVolume:


{{{
# The field definition
parent = models.ForeignKey(
        'BracketVolume', null=True, blank=True, to_field='uuid',
        related_name='parent_templates')

# We start with a queryset of one which has a BracketVolumeTemplate which refers to a BracketVolume via the parent filed
ipdb> queryset
[<BracketVolumeTemplate [snapshot based] ID: 10dc67d94f8347d195e25eca6f3c22bb - created by test@brkt.com>]
ipdb> queryset[0].parent
<BracketVolume [snapshot] Requested State: DELETED ID: 2de07185d9744fdd83b5f683dfe5a2aa - created by test@brkt.com>

# The parent_id is correctly set as the UUID
ipdb> queryset[0].parent_id
u'2de07185d9744fdd83b5f683dfe5a2aa'

# We are updating with the kwargs as follows
ipdb> kwargs
{'parent': <BracketVolume [snapshot] Requested State: AVAILABLE ID: 62b72525425b4252925ba9ce48d42428 - created by test@brkt.com>}
ipdb> queryset.update(**kwargs)
1

# Wait, parent_id should be the UUID, but instead the pk is used for the foreign key
ipdb> queryset[0].parent_id
u'3'

# Now the relationship is broken
ipdb> queryset[0].parent
*** DoesNotExist: BracketVolume matching query does not exist. Lookup parameters were {'uuid__exact': u'3'}

# Queryset hides the db_columns, so we can't work around directly
ipdb> queryset.update(parent_id='2de07185d9744fdd83b5f683dfe5a2aa')
*** FieldDoesNotExist: BracketVolumeTemplate has no field named 'parent_id'

# The below workaround does work...
ipdb> queryset.update(parent='2de07185d9744fdd83b5f683dfe5a2aa')
1
ipdb> queryset[0].parent
<BracketVolume [snapshot] Requested State: DELETED ID: 2de07185d9744fdd83b5f683dfe5a2aa - created by test@brkt.com>
ipdb> c
}}}

I can work around this by adding the following code in my update code, but it's not ideal:

{{{
for key in kwargs:
            field = queryset.model._meta.get_field(key)
            if isinstance(field, ForeignKey):
                model = kwargs[key]
                if not model:
                    continue
                rel_att = field.rel.field_name
                kwargs[key] = getattr(model, rel_att)
        queryset.update(modified_by=modified_by_id, **kwargs)
}}}"	Bug	closed	Database layer (models, ORM)	dev	Normal	fixed		berndtj@…	Accepted	1	0	0	0	0	0