#32332: Saving parent object after setting on child leads to data loss for
parents
with non-numeric primary key.
-------------------------------------+-------------------------------------
Reporter: Charlie DeTar | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 3.1
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Mariusz Felisiak):
* cc: robinh00d, Jon Dufresne (added)
Comment:
Thanks for this report. `product_id` is an empty string in
[https://github.com/django/django/blob/2d6179c819010f6a9d00835d5893c4593c0b85a0/django/db/models/base.py#L936-L939
_prepare_related_fields_for_save()] that's why `pk` from a related object
is not used. We could use `empty_values`:
{{{
diff --git a/django/db/models/base.py b/django/db/models/base.py
index 822aad080d..8e7a8e3ae7 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -933,7 +933,7 @@ class Model(metaclass=ModelBase):
"%s() prohibited to prevent data loss due to
unsaved "
"related object '%s'." % (operation_name,
field.name)
)
- elif getattr(self, field.attname) is None:
+ elif getattr(self, field.attname) in field.empty_values:
# Use pk from related object if it has been saved
after
# an assignment.
setattr(self, field.attname, obj.pk)
}}}
but I'm not sure.
Related with #28147.
--
Ticket URL: <https://code.djangoproject.com/ticket/32332#comment:2>
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