Back
Feb 18, 2010

Business logic in models

In my recent project there was a lot of data business logic, so I had to organize this code somehow. In this article I'll describe a few hints on how to it.

Mixins

Simple business logic functions should in models or managers. When there's a lot of them, the can be split in mixins.

# logic.py
class EventLogic(object):
    def start(self):
        if self.condition():
            # ...


# models.py
class Event(models.Model, EventLogic):
    name = models.CharField()
    # ...

Custom exceptions

For business logic errors you should declare custom exception classes. It's not fun to understand what this specific IntegrityError means.

Generic views

When all logic is in model and can throw, say, BusinessLogicException, we can write views like this:

from django.contrib import messages


def event_action(requets, event_id, action):
    # event = get_object_or_404(...)
    try:
        getattr(event, action)(request.user)
    except BusinessLogicException, e:
        messages.warning(request, e.message)

    return redirect(request.POST.get('next') or event)

Subscribe for the news and updates

More thoughts
Apr 11, 2024Technology
Test Analysis at the Feature Level

In the previous article, we learned about test analysis for a product in general, and now we are ready to go further and look at test analysis for specific features.

Jun 27, 2018Technology
How to Work With Legacy Code: Code Refactoring Techniques

In this article we'll review general approach to working with the best kind of projects - the ones with old untested and undocumented spaghetti code and a tight schedule. We'll review anger management techniques, coping mechanisms and some refactoring tips that might come in handy.

May 10, 2018Technology
How to Build a Cloud-Based Leads Management System for Universities

Lead management is an important part of the marketing strategy of every company of any size. Besides automating various business processes, privately-held organizations should consider implementing an IT solution that would help them manage their leads. So, how should you make a web-based leads management system for a University in order to significantly increase sales?

Jun 14, 2017Technology
How to Deploy a Django Application on Heroku?

In this article I'll show you how to deploy Django with Celery and Postgres to Heroku.

Mar 3, 2017Technology
Flask vs Django. Which Is Better for Your Web App?

There are two most popular web frameworks in Python. There is the Django with lots of intelligent defaults and the Flask micro framework with complete freedom in the choice of modules. Let’s see, what django vs flask is in 2017.

Jan 12, 2017Technology
Making Custom Report Tables Using AngularJS and Django

In this article I will tell you how to create an interactive interface with a widely customized visual look and different filtering to view reports.