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
Mar 26, 2025Technology
Common Mistakes and Recommendations for Test Cases

The article highlights common test case mistakes, offers ways to fix them, and provides practical tips to improve and optimize test cases.

Apr 15, 2024Technology
Lazy Promises in Node.js

Promise is a powerful tool in asynchronous programming that allows developers to call a time-consuming function and proceed with program execution without waiting for the function result.

Aug 18, 2022Technology
5 Best Practices of RESTful API Design to Keep Your Users Happy

Dive into our guide to RESTful API best practices

May 22, 2017Technology
Web Application Security: 10 Best Practices

Protection of WEB App is of paramount importance and it should be afforded the same level of security as the intellectual rights or private property. I'm going to cover how to protect your web app.

Oct 3, 2016Technology
How to include JQuery plugins in Angular 2 running via webpack

Learn more about how to include jquery plugins in angular 2 running via webpack. Our tutorial is perfect for Angular beginners.

Aug 31, 2016Technology
Angular vs React Comparison

In this article, we will compare two most popular JS Libraries (Angular vs React). Both of them were created by professionals and have been used in famous big projects.