fixture loading fails for one-to-one relations

[zhaoz]

Models created with one-to-one relation as ​documented fail to produce loadable fixtures.

Fixtures created with dumpdata and then reloaded with loaddata fail with this error:

ERROR:  duplicate key violates unique constraint "App_model_pkey"

Tested with dumpdata using json on postgresql.

---

Also tested on sqlite

Models:

from django.db import models

# Create your models here.
class Parent(models.Model):
    name = models.CharField(max_length=60, unique=True)

class Child(Parent):
    parent = models.OneToOneField(Parent, parent_link=True)
    number = models.IntegerField(max_length=20)

Dumpdata

$ ./manage.py dumpdata --format=json first > first/fixtures/test.json
$ cat first/fixtures/test.json
[{"pk": 1, "model": "first.parent", "fields": {"name": "first1"}}, {"pk": 1, "model": "first.child", "fields": {"name": "first1", "number": 2}}]
$ ./manage.py loaddata test
Installing json fixture 'test' from '/home/zhaoz/programming/python/django_test/onetoone/../onetoone/first/fixtures'.
Problem installing fixture '/home/zhaoz/programming/python/django_test/onetoone/../onetoone/first/fixtures/test.json': column name is not unique

[zhaoz]

Adds a test for onetoone fixture loading -- (needs the onetoone.json fixture)

[zhaoz]

The fixture to be used with the onetoone test.

[zhaoz]

Renamed the .patch to .diff

[zhaoz]

The fix, sets parent's pk so update/save new works correctly.

[zhaoz]

Patch actually fails for some cases. Will need to look at patch/test case.

[zhaoz]

The patch works for every case with the exception of when the parent model and the child model share the same pk field name.

[Russell Keith-Magee]

(In [7600]) Fixed #7350, #7202 -- Fixed serialization for multi-model inheritance, which had multiple problems:

• Serializers were including all superclass fields in their output. Now only local fields are included.
• Implicit OneToOne primary keys were not correctly added to the metamodel, so they were always marked to be serialized, even though they were primary
• Model saving was too aggressive about creating new parent class instances during deserialization. Raw save on a model now skips saving of the parent class.