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...
First install the django-conditions package:
pip install django-conditions
Then add conditions to your INSTALLED_APPS setting:
## settings.py
INSTALLED_APPS = [
...
'conditions',
]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.
Full documentation is available on Read The Docs.