Skip to main content

Stores named references to specific instances of any model in the database.

Project description

``django-model-reference`` defines a simple :cls:`model_reference.Reference`
model that hold named references to specific instances of any Django model.

Usage
=====

References are controlled by the :func:`register()` and :func:`load` functions of
the ``model_reference`` module. These function are also mirrored by the
corresponding methods in the ``Reference.objects`` manager. To register a
reference, simply pass the object and either a unique name or a unique suffix::

from model_reference import register, load
from django.contrib.auth.models import User

# Fetch some objects
john = User.objects.get(username='john')
ringo = User.objects.get(username='ringo')

# Register references in the database
register(john, 'favorite beatle')
register(ringo, suffix='drummer')

The name for each reference is unique. If the register function is called with
the explicit ``suffix`` argument, it will register the instance as
``<app_label>.<model>:suffix``, which in our case becomes ``'auth.user:drummer'``.

In order to retrieve the objects referred by the Reference object, we can use
the :func:`load` function::

>>> load('favorite beatle')
<User: john>
>>> load('drummer', model=User)
<User: ringo>

Objects registered with the suffix form of the register function should pass a
model class in order to construct the complete name string. This is equivalent
as creating the string by hand:

>>> load('auth.user:drummer')
<User: ringo>


Empty references
================

If one request a non-existing reference to the load() function, it raises an
:error:`model_reference.EmptyReferenceError`. Users can register factory
functions to create these objects on-the-fly.

The default way of registering factory function is via the :func:`model_reference.factory`
decorator. It must be called with a reference string (or suffix + model) and
decorates a function that return a new instance and is called without arguments::

@factory('drummer', model=User)
def make_ringo():
user, created = User.object.get_or_create(
username=ringo,
first_name='Richard'
last_name='Starkley',
email='ringo@applerecords.co.uk'
)
return user

If a new instance is created, the function is responsible to save it in the
database

Project details


Release history Release notifications

This version
History Node

0.1.1

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging CloudAMQP CloudAMQP RabbitMQ AWS AWS Cloud computing Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page