Reverse generic relation to a model inheriting from the model defining a generic relation confuses flush

[pronik]

Please look into attached file, I've created a minimal test project for this bug. You'll have to include your database credentials in settings.py before you try it.

Let's say we have model with a generic relation (e.g. django.contrib.comments.models.Comment) and a model deriving from it (e.g. OtherComment). Now, if a reverse generic relation to OtherComment is defined, it would correctly work and point to a list of OtherComment instances. However, flush would now try to reset the sequence on id field of OtherComment which does not exist (OtherComment only has comment_ptr_id) while resetting id on Comment would be correct.

[pronik]

Minimal project reproducing the problem

[pronik]

Forgot to mention: this is on PostgreSQL 9.1, however, I assume this bug could be relevant for other DBMS.

[Aymeric Augustin]

In addition to configuring a database, you'll have to add 'django.contrib.comments' to INSTALLED_APPS for the provided project to work.

Here's the traceback:

(django-dev)myk@mYk djangobug % python manage.py syncdb
Creating tables ...
Creating table auth_permission
Creating table auth_group_permissions
Creating table auth_group
Creating table auth_user_user_permissions
Creating table auth_user_groups
Creating table auth_user
Creating table django_comments
Creating table django_comment_flags
Creating table django_content_type
Creating table django_session
Creating table django_site
Creating table my_comments_othercomment
Creating table my_comments_somethingcommented

You just installed Django's auth system, which means you don't have any superusers defined.
Would you like to create one now? (yes/no): no
Installing custom SQL ...
Installing indexes ...
Installed 0 object(s) from 0 fixture(s)

(django-dev)myk@mYk djangobug % python manage.py flush --traceback
You have requested a flush of the database.
This will IRREVERSIBLY DESTROY all data currently in the 'throwaway' database,
and return each table to the state it was in after syncdb.
Are you sure you want to do this?

    Type 'yes' to continue, or 'no' to cancel: yes
Traceback (most recent call last):
  File "/Users/myk/Documents/dev/django-trunk/django/core/management/base.py", line 222, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/myk/Documents/dev/django-trunk/django/core/management/base.py", line 252, in execute
    output = self.handle(*args, **options)
  File "/Users/myk/Documents/dev/django-trunk/django/core/management/base.py", line 382, in handle
    return self.handle_noargs(**options)
  File "/Users/myk/Documents/dev/django-trunk/django/core/management/commands/flush.py", line 67, in handle_noargs
    The full error: %s""" % (connection.settings_dict['NAME'], e))
CommandError: Database throwaway couldn't be flushed. Possible reasons:
  * The database isn't running or isn't configured correctly.
  * At least one of the expected database tables doesn't exist.
  * The SQL was invalid.
Hint: Look at the output of 'django-admin.py sqlflush'. That's the SQL this command wasn't able to run.
The full error: column "id" of relation "my_comments_othercomment" does not exist

CommandError: Database throwaway couldn't be flushed. Possible reasons:
  * The database isn't running or isn't configured correctly.
  * At least one of the expected database tables doesn't exist.
  * The SQL was invalid.
Hint: Look at the output of 'django-admin.py sqlflush'. That's the SQL this command wasn't able to run.
The full error: column "id" of relation "my_comments_othercomment" does not exist

[Ramiro Morales]

I'm going to close this as a duplicate of #13203 that now is about this same issue.