Loaddata on dumpdata'd subclass fails

[jeroen.pulles@…]

I have a problem with loaddata on a subclass of contrib.auth.User. The dumpdata generates data that looks fine. The JSON I get is identical to Django 1.5 which loads just fine. Loaddata in 1.6b1 fails to load that data, however. I get the impression that it is caused by subclassing, as none of the other relations in the models cause trouble. I have attached a small sample project with just the subclass to reproduce the problem ("sample.zip").

Loaddata crashes with this exception ValueError: Problem installing fixture '/Volumes/prj/myapp/fixtures/ennu.json': "<MiniUser: >" needs to have a value for field "user" before this many-to-many relationship can be used. (This is the user-permission related manager complaining, by the way)

This is what the MiniUser model looks like:

class MiniUser(User):
    mini = models.IntegerField()

This is a snippet from dumpdata:

...
  {
    "pk": 1,
    "model": "myapp.miniuser",
    "fields": {
      "user_permissions": [],
      "mini": 123,
      "groups": []
    }
...

When I remove the "user_permissions" and "groups" properties (from auth.User) from the myapp.miniuser json, loaddata completes just fine.

[jeroen.pulles@…]

minimal sample project for reproduction

[Tim Graham]

I can reproduce this and it indeed appears to be a regression in 1.6.

[Tim Graham]

regression test

[Tim Graham]

Added a regression test. The commit that introduced the issue is 97774429aeb54df4c09895c07cd1b09e70201f7d.

[Anssi Kääriäinen <akaariai@…>]

In 1ed77e7782069e938e896a0b8d0fd50156ed3680:

Fixed #20820 -- Model inheritance + m2m fixture loading regression

Tests by Tim Graham, report from jeroen.pulles@….

[Anssi Kääriäinen <akaariai@…>]

In 2b1101a4a6acbf9350b62638a04edcf20ad83e97:

[1.6.x] Fixed #20820 -- Model inheritance + m2m fixture loading regression

Tests by Tim Graham, report from jeroen.pulles@….

Backport of 1ed77e7782 from master

[Andrew Godwin <andrew@…>]

In f5552571dc7a0d9da9df1d108bc4bbef6857c157:

Fixed #20820 -- Model inheritance + m2m fixture loading regression

Tests by Tim Graham, report from jeroen.pulles@….