django-conditions

Move conditional logic that changes often from code into models so that the logic can be easily modified in admin. Some possible use cases:

• Segment your user base into cohorts with targeted messaging
• Provide different rewards to users depending on their expected value
• In a game, define the winning objectives of a mission/quest
• and many more...

Installation

First install the django-conditions package:

pip install django-conditions

Then add conditions to your INSTALLED_APPS setting:

## settings.py
INSTALLED_APPS = [
    ...
    'conditions',
]

Basic Usage

Start by defining a condition in code:

## condition_types.py
from conditions import Condition

class FullName(Condition):
    # The name that appears in the db and represents your condition
    condstr = 'FULL_NAME'

    # Normal conditions define eval_bool, which takes in a user
    # and returns a boolean
    def eval_bool(self, user, **kwargs):
        return bool(user.first_name and user.last_name)

Then add a ConditionsField to your model:

## models.py
from django.db import models
from conditions import ConditionsField, conditions_from_module
import condition_types

class Campaign(models.Model):
    text = models.TextField()

    # The ConditionsField requires the definitions of all possible conditions
    # conditions_from_module can take an imported module and sort this out for you
    target = ConditionsField(definitions=conditions_from_module(condition_types))

In the model's change form on admin, you can enter JSON to represent when you want your condition to be satisfied.

{
    "all": ["FULL_NAME"]
}

Now you can use the logic you created in admin to determine the outcome of an event:

## views.py
from django.http import HttpResponse
from conditions import eval_conditions
from models import Campaign

def profile(request):
    for campaign in Campaign.objects.all():
        if eval_conditions(campaign, 'target', request.user):
            return HttpReponse(campaign.text)

    return HttpResponse("Nothing new to see.")

Use django-conditions in your Django projects to change simple logic without having to re-deploy, and pass on the power to product managers and other non-engineers.

More Information

Full documentation is available on Read The Docs.