id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
29350	Sqlite3 Introspection (get_primary_key_column) Always Returns None	Zackary Troop	Zackary Troop	"Hello, I've noticed that the `get_primary_key_column` method always returns `None`, even though a Primary Key is present in the table. I am using the sqlite3 backend. I've captured the steps to reproduce below.

Create new environment, install Django.
{{{
(env) system :: ~/OpenSource/testing % pip3 install django                                                                                                                       
Collecting django
  Downloading https://files.pythonhosted.org/packages/89/f9/94c20658f0cdecc2b6607811e2c0bb042408a51f589e5ad0cb0eac3236a1/Django-2.0.4-py3-none-any.whl (7.1MB)
    100% |████████████████████████████████| 7.1MB 504kB/s 
Collecting pytz (from django)
  Downloading https://files.pythonhosted.org/packages/dc/83/15f7833b70d3e067ca91467ca245bae0f6fe56ddc7451aa0dc5606b120f2/pytz-2018.4-py2.py3-none-any.whl (510kB)
    100% |████████████████████████████████| 512kB 694kB/s 
Installing collected packages: pytz, django
Successfully installed django-2.0.4 pytz-2018.4
}}}

Create new sqlite3 database called `test.sqlite3` and add a new table with a Primary Key.
{{{
(env) system :: OpenSource/testing/testapp % sqlite3 test.sqlite3
SQLite version 3.23.1 2018-04-10 17:39:29
Enter "".help"" for usage hints.
sqlite> CREATE TABLE `food` (
   ...>   id int PRIMARY KEY NOT NULL,
   ...>   food_group_id int REFERENCES food_group(id) NOT NULL,
   ...>   long_desc text NOT NULL DEFAULT '',
   ...>   short_desc text NOT NULL DEFAULT ''
   ...> );
sqlite> .exit
}}}

Add database profile to settings.
{{{
(env) system :: OpenSource/testing/testapp % nano testapp/settings.py 

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    },
    'testdb': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'test.sqlite3'),
    }
}
}}}

Open Django shell, verify table existance and try to determine if a Primary Key is present.
{{{
(env) system :: OpenSource/testing/testapp % python manage.py shell
>>> from django.db import connections
>>> from django.db.backends.sqlite3 import introspection
>>> db_conn = connections['testdb']
>>> cur = db_conn.cursor()
>>> introspection.DatabaseIntrospection(db_conn).get_table_list(cur)
[TableInfo(name='food', type='t')]
>>> answer = introspection.DatabaseIntrospection(db_conn).get_primary_key_column(cur, 'food')
>>> type(answer)
<class 'NoneType'>
}}}
"	Bug	closed	Database layer (models, ORM)	2.0	Normal	fixed	sqlite3		Ready for checkin	1	0	0	0	0	0