Djony

Whats new?

2013-11-07:

The tastypie_djony package using djony has been issued https://github.com/nnseva/tastypie_djony

Some fixes and improvements

2013-10-14:

The first release (for MySQL only a while)

Base

NOTE: this package has been inspired by aldjemy package.

Small package for integration Pony ORM (http://doc.ponyorm.com/) into an existent Django (https://docs.djangoproject.com) project. The primary use case of this package is building fast-processing queries - 6-7 times faster than through the native Django ORM.

You need to include djony at the END (required) of INSTALLED_APPS. Note that only models known in installed apps above the djony will be integrated. When models are imported, djony will read all models and contribute p attribute to them. The p attribute is a Pony model class (mapped to the default database) equivalent to the correspondent Django model.

Code example:

from djony import orm
r = {}
with orm.db_session:
  for u in orm.select(u for u in User.p):
    r[u.username] = {}
    for p in u.user_permissions:
     if not r[u.username].get((p.content_type.app_label,p.content_type.model)):
      r[u.username][(p.content_type.app_label,p.content_type.model)] = {}
     r[u.username][(p.content_type.app_label,p.content_type.model)][p.codename] = p.codename
print "PERMISSIONS:",r

You can use other databases declared in the settings.py DATABASES variable.

Use orm.db(alias) to get the other database, and db.djony_<package>_<classname> members to get access to the correspondent pony model.

Using other databases example (let the other database is identified by other_alias in Django DATABASES settings):

from djony import orm
db = orm.db(other_alias)
with orm.db_session:
  for u in orm.select(u for u in db.djony_auth_User):
    print "USERNAME:",u.username

Limitations

• No mapping for ForeignKey(to_field=...), the correspondent attribute is converted to simple one
• No mapping for partial database mapping (the only full one is supported)
• Django inheritance is mapped to Pony one-to-one relationship with parent entity; the default name of parent reference attribute is <lowercase-parent-class-name>_ptr

Notes

The djony is not positioned as Django ORM drop-in replacement. It's a helper for special situations.

We have some stuff in the djony cache too:

from djony import orm
orm.db() # The 'default' database for Pony ORM
orm.db(other_alias) # The other_alias database for Pony ORM

You can use this stuff if you need.

Settings

You can add your own primitive data types mappings for djony using DJONY_PRIMITIVE_DATA_TYPES settings parameter. See the PRIMITIVE_DATA_TYPES in the orm.py.

You can correct list of string-based primitive field internal types using DJONY_STRING_FIELD_INTERNAL_TYPES list.

You can add engines to use with djony using DJONY_ENGINES settings. The format is like the following:

{
    ...
    'mysql': {
        'provider':'mysql',
        'args_convertor':mysql_get_args,
    },
}

where the 'args_converter' is a function taking database settings dictionary from Django and returing dictionary of pony-style keyword parameters passed to the pony provider class constructor.

TODO-LIST

1. Support for all database libraries common for Django and Pony
2. Regression testing
3. Testing for threading compatibility
4. Stress-tests for production environments
5. Django-vs-pony productivity comparison tests for production environments

Pull requests are very appretiated!

Roadmap

Rewriting some Django applications to use djony instead of Django ORM

Never be implemented

1. Query syntax compatibility with Django ORM
2. Mapping for Django-style inheritance