hstore with cursor_factory=psycopg2.extras.RealDictCursor Errors

[bgcgarlipp]

Hi

When intializing a new connection with cursor_factory=psycopg2.extras.RealDictCursor on a databse with hstore extension on, you get an error as follows. This is due to a dict being returned as result and not list.

Traceback (most recent call last):
File "wsclient.py", line 134, in
loop.run_until_complete(db.init_db())
File "/usr/lib/python3.5/asyncio/base_events.py", line 337, in run_until_complete
return future.result()
File "/usr/lib/python3.5/asyncio/futures.py", line 274, in result
raise self._exception
File "/usr/lib/python3.5/asyncio/tasks.py", line 239, in _step
result = coro.send(None)
File "/home/bernhardt/git_work/qs_switch/QS_Workflow/client/async_quantdb.py", line 25, in init_db
cursor_factory=psycopg2.extras.RealDictCursor)
File "/home/bernhardt/git_work/qs_switch/QS_Workflow/pyenv/lib/python3.5/site-packages/aiopg/utils.py", line 57, in await
resp = yield from self._coro
File "/home/bernhardt/git_work/qs_switch/QS_Workflow/pyenv/lib/python3.5/site-packages/aiopg/pool.py", line 45, in _create_pool
yield from pool._fill_free_pool(False)
File "/home/bernhardt/git_work/qs_switch/QS_Workflow/pyenv/lib/python3.5/site-packages/aiopg/pool.py", line 188, in _fill_free_pool
**self._conn_kwargs)
File "/home/bernhardt/git_work/qs_switch/QS_Workflow/pyenv/lib/python3.5/site-packages/aiopg/utils.py", line 52, in iter
resp = yield from self._coro
File "/home/bernhardt/git_work/qs_switch/QS_Workflow/pyenv/lib/python3.5/site-packages/aiopg/connection.py", line 78, in _connect
oids = yield from _enable_hstore(conn)
File "/home/bernhardt/git_work/qs_switch/QS_Workflow/pyenv/lib/python3.5/site-packages/aiopg/connection.py", line 37, in _enable_hstore
rv0.append(oids[0])
KeyError: 0

How to reproduce:
install

sudo apt-get install postgresql-contrib
create hstore extension on database

CREATE EXTENSION hstore;

create connection to datbase using aiopg, we created a pool, but as it calls connect function inside normal conection should fail aswell
self._pool = await aiopg.create_pool(host=self.settings.DATABASE_HOST, database=self.settings.DATABASE_NAME, user=self.settings.DATABASE_USER, password=self.settings.DATABASE_PASS, port=self.settings.DATABASE_PORT, cursor_factory=psycopg2.extras.RealDictCursor)

Suggested solution:
Change "def _enable_hstore(conn):" in aiopg.connection
from

@asyncio.coroutine
def _enable_hstore(conn):
    cur = yield from conn.cursor()
    yield from cur.execute("""\
        SELECT t.oid, typarray
        FROM pg_type t JOIN pg_namespace ns
            ON typnamespace = ns.oid
        WHERE typname = 'hstore';
        """)
    rv0, rv1 = [], []
    for oids in (yield from cur.fetchall()):
        rv0.append(oids[0])
        rv1.append(oids[1])
    cur.close()
    return tuple(rv0), tuple(rv1)

To

@asyncio.coroutine
def _enable_hstore(conn):
    cur = yield from conn.cursor()
    yield from cur.execute("""\
        SELECT t.oid, typarray
        FROM pg_type t JOIN pg_namespace ns
            ON typnamespace = ns.oid
        WHERE typname = 'hstore';
        """)
    rv0, rv1 = [], []
    for oids in (yield from cur.fetchall()):
        if type(oids) is list:
            rv0.append(oids[0])
            rv1.append(oids[1])
        else:
            rv0.append(oids['oid'])
            rv1.append(oids['typarray'])
    cur.close()
    return tuple(rv0), tuple(rv1)

Regards

[jettify]

@bgcgarlipp thanks for report! would you like to create PR?