Usage

Getting Started

Prerequisites

• Django version 1.2 or greater (may work with earlier versions but untested)

Installation

Note

We assume you’re using pip+virtualenv+virtualenvwrapper. If not, start now.

Install django-genia:

$ pip install django-genia

Setup

The easiest way to get started is to edit your Django app’s models.py to use genia.models.GenerationalModelMixin:

from django.db import models
from genia.models import GenerationalModelMixin

class Person(GenerationalModelMixin, models.Model):
    name = models.CharField(max_length=100)

    def __unicode__(self):
        return self.name

This mixin will add a generation field to your model which is a ForeignKey to a genia.models.Generation. It also overrides your model’s default manager to use genia.models.GenerationalModelManager.

If you need to customize this (e.g. your model already has its own custom manager), you can use the following template:

from django.db import models
from genia.models import Generation, GenerationalModelManager

class Person(models.Model):
    name = models.CharField(max_length=100)
    generation = models.ForeignKey(Generation)
    objects = YourCustomManager()
    active_objects = GenerationalModelManager()

    def __unicode__(self):
        return self.name

If your model defines fields with unique=True, they may not work as expected. In this case, you should update your model definition to use unique_together along with the generation field.

Usage

The basic use case is if you have to import a lot of data at once into an app, but you don’t want it to “go live” until it’s all done loading. In this case, you would follow the following workflow:

1. Create a new generation
2. Start importing your data against this new generation
3. Once the import completes, set the new generation to be active

Here’s an interactive session showing this workflow:

>>> from genia.models import Generation
>>> from my_app.loader import load_people
>>> new_gen = Generation('my_app')
>>> load_people(generation=new_gen)
...
>>> new_gen.make_active()