I tried to use django-hstore using this nice tutorial. I added two classes to an existing app managed by South:
class Attribute(models.Model):
name = models.CharField(max_length=200, verbose_name=_("name"))
description = models.CharField(max_length=1000, verbose_name=_("description"))
class Measure(models.Model):
attribute = models.ForeignKey(Attribute)
data = hstore.DictionaryField(db_index=True)
objects = hstore.HStoreManager()
made a schemamigration --auto
, launched the migration and got a django.db.utils.DatabaseError: type "hstore" does not exist
.
Okay, the tuto seemed to be incomplete, the django-hstore documentation told me to use the custom database backend, i added the following to my settings file:
DATABASES['default']['ENGINE'] = 'django_hstore.postgresql_psycopg2'
Then I got a KeyError: 'default'
in south/db/__init__.py", line 78
. At this point, the intertubes + some trial/errors pointed me to the SOUTH_DATABASE_ADAPTERS
settings variable and I added the following to the settings:
SOUTH_DATABASE_ADAPTERS = {'default': 'south.db.postgresql_psycopg2'}
New error:
File ".../psycopg2/extras.py", line 769, in register_hstore
"hstore type not found in the database. "
psycopg2.ProgrammingError: hstore type not found in the database. please install it from your 'contrib/hstore.sql' file
Now this is odd because I installed the hstore extension :
$ sudo -u postgres psql
create extension hstore;
postgres=# CREATE EXTENSION hstore;
ERROR: extension "hstore" already exists
postgres=# \dx
List of installed extensions
Name | Version | Schema | Description
---------+---------+------------+--------------------------------------------------
hstore | 1.0 | public | data type for storing sets of (key, value) pairs
plpgsql | 1.0 | pg_catalog | PL/pgSQL procedural language
(2 rows)
postgres=# SELECT 'hstore'::regtype::oid;
oid
-------
57704
(1 row)
How is this supposed to work ? I'm using Django 1.4, Postgresql 9.1.
I eventually found that the hstore extension wasn't installed for the specific database I was using:
$ psql -d mydb
psql (9.1.4)
Type "help" for help.
mydb=# SELECT t.oid, typarray FROM pg_type t JOIN pg_namespace ns ON typnamespace = ns.oid WHERE typname = 'hstore';
oid | typarray
-----+----------
(0 rows)
mydb=# \dx
List of installed extensions
Name | Version | Schema | Description
---------+---------+------------+------------------------------
plpgsql | 1.0 | pg_catalog | PL/pgSQL procedural language
(1 row)
mydb=# create extension hstore;
WARNING: => is deprecated as an operator name
DETAIL: This name may be disallowed altogether in future versions of PostgreSQL.
CREATE EXTENSION
mydb=# \dx
List of installed extensions
Name | Version | Schema | Description
---------+---------+------------+--------------------------------------------------
hstore | 1.0 | public | data type for storing sets of (key, value) pairs
plpgsql | 1.0 | pg_catalog | PL/pgSQL procedural language
(2 rows)
mydb=# SELECT t.oid, typarray FROM pg_type t JOIN pg_namespace ns ON typnamespace = ns.oid WHERE typname = 'hstore';
oid | typarray
-------+----------
58800 | 58805
(1 row)
I thought that a database created after the hstore installation would include the extension. Doesn't seem to be the case, am I misinterpreting how extensions work ? Are they database-specific ?