django-eav

Introduction

This is a fork of https://github.com/mvpdev/django-eav to adapt different things:

Make it Python 3 compatible
Make it Django 2.0 compatible
Remove dependency on Django Site framework
Allow a custom Entity class and custom EntityManager class (this is particular useful to override the get_all_attributes method and change the logic to filter a given Entity attributes, like assigning attributes at model instance level).
Make Attribute slug unique for Attribute
Make name and content_type unique for Attribute
Build Attribute slug using name and content_type, thus using the name directly (ex: color) would not work. Use set_value() of Entity instead.
Add contraint at database level that a Value for an Attribute can exist only once for an entity record.
Add object_content_type to define the (optional) ContentType of an object Attribute
Add TYPE_DECIMAL attribute type (using django DecimalValidator)
Add TYPE_POINT and TYPE_MULTIPOLYGON Attribute types, relying on GeoDjango
Add size for Attribute displaying configuration
Add a global EAV_REGISTRATION` setting to turn on/off registration
Add a model_bypass_required() method to ``Entity` to allow overriding in a custom class and permit some models to have required attributes without value

The EavConfig now includes two new attributes entity_class and entity_manager, that default to Entity and EntityManager respectively.

What is this useful for? Let's say you want to filter the attributes of a given instance based on values, tags or any relational information related to that specific instance. Then, you could specify your custom Entity class and override the get_all_attributes() method.

WARNING: If you have non unique slug values in your database you will need to update them before running the migrations.

django-eav provides an Entity-Attribute-Value storage model for django apps.

For a decent explanation of what an Entity-Attribute-Value storage model is, check Wikipedia.

Note

This software was inspired / derived from the excellent eav-django written by Andrey Mikhaylenko.

There are a few notable differences between this implementation and the eav-django implementation.

This one is called django-eav, whereas the other is called eav-django.
This app allows you to to 'attach' EAV attributes to any existing django model (even from third-party apps) without making any changes to the those models' code.
This app has slightly more robust (but still not perfect) filtering.

Installation

From Github

You can install django-eav directly from github:

pip install -e git+git://github.com/sromero84/django-eav.git#egg=django-eav

Run migrate

Usage

Edit settings.py

Add eav to your INSTALLED_APPS in your project's settings.py file.

Register your model(s)

Before you can attach eav attributes to your model, you must register your model with eav:

>>> import eav
>>> eav.register(MyModel)

Generally you would do this in your models.py immediate after your model declarations. Alternatively, you can use the registration decorator provided:

from eav.decorators import register_eav
@register_eav()
class MyModel(models.Model):
    ...

Create some attributes

>>> from eav.models import Attribute
>>> Attribute.objects.create(name='Weight', datatype=Attribute.TYPE_FLOAT)
>>> Attribute.objects.create(name='Color', datatype=Attribute.TYPE_TEXT)

Assign eav values

>>> m = MyModel()
>>> m.eav.weight = 15.4
>>> m.eav.color = 'blue'
>>> m.save()
>>> m = MyModel.objects.get(pk=m.pk)
>>> m.eav.weight
15.4
>>> m.eav.color
blue

>>> p = MyModel.objects.create(eav__weight = 12, eav__color='red')

Filter on eav values

>>> MyModel.objects.filter(eav__weight=15.4)

>>> MyModel.objects.exclude(name='bob', eav__weight=15.4, eav__color='red')

Documentation and Examples

<http://mvpdev.github.com/django-eav>