“Duplicate key value” error when running Django tests on auth

问题

I have a Django site that's working fine. It has a small amount of data in the database which I want to use for testing. I've done dumpdata to generate a few .json fixtures. But, when I try to run a test on my app ("tagger") I get a Postgresql error, and I can't work out how to solve it:

(django-projectname)$ ./manage.py test tagger
Creating test database for alias 'default'...
Problem installing fixture '/Users/phil/Projects/RIG/projectname/django-projectname/projectname/tagger/fixtures/auth_testdata.json': Traceback (most recent call last):
  File "/Users/phil/.virtualenvs/django-projectname/lib/python2.6/site-packages/django/core/management/commands/loaddata.py", line 174, in handle
    obj.save(using=using)
  File "/Users/phil/.virtualenvs/django-projectname/lib/python2.6/site-packages/django/core/serializers/base.py", line 165, in save
    models.Model.save_base(self.object, using=using, raw=True)
  File "/Users/phil/.virtualenvs/django-projectname/lib/python2.6/site-packages/django/db/models/base.py", line 526, in save_base
    rows = manager.using(using).filter(pk=pk_val)._update(values)
  File "/Users/phil/.virtualenvs/django-projectname/lib/python2.6/site-packages/django/db/models/query.py", line 491, in _update
    return query.get_compiler(self.db).execute_sql(None)
  File "/Users/phil/.virtualenvs/django-projectname/lib/python2.6/site-packages/django/db/models/sql/compiler.py", line 869, in execute_sql
    cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
  File "/Users/phil/.virtualenvs/django-projectname/lib/python2.6/site-packages/django/db/models/sql/compiler.py", line 735, in execute_sql
    cursor.execute(sql, params)
  File "/Users/phil/.virtualenvs/django-projectname/lib/python2.6/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 44, in execute
    return self.cursor.execute(query, args)
IntegrityError: duplicate key value violates unique constraint "auth_permission_content_type_id_codename_key"
DETAIL:  Key (content_type_id, codename)=(3, add_htuser) already exists.

I tried doing dumpdata for the auth app using the --natural flag too, but that didn't change anything. I'm stumped, and can't work out where it's getting a duplicate key from.

The "htuser" class that it refers to is a Proxy model on the auth User class.

I'm using South for my apps' migrations and it sounds like https://stackoverflow.com/a/2888916/250962 may be the answer, but I don't understand how to "Remove the explicitly-set primary key values from the datamigrations"?

来源：https://stackoverflow.com/questions/8840068/duplicate-key-value-error-when-running-django-tests-on-auth