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
Dec 22, 2024Technology
Python and the Point Rush in DeFi

This article demonstrates how to use Python to automate yield calculations in decentralized finance (DeFi), focusing on the Renzo and Pendle platforms. It guides readers through estimating potential rewards based on factors like token prices, liquidity, and reward distribution rules, emphasizing the importance of regular data updates and informed decision-making in DeFi investments.

Mar 18, 2024Technology
From boring to exciting: turn learning to code into an adventure

Tired of boring programming courses where you're forced to read thick textbooks and write code that's never used? Need a platform that makes learning fun and exciting? Then you're in the right place!

Apr 18, 2023Technology
TDD guide for busy people, with example

This quick introduction to TDD is meant to show the implementation of this practice with a real-life example.

Nov 29, 2022Technology
React Performance Testing with Jest

One of the key requirements for modern UI is being performant. No matter how beautiful your app looks and what killer features it offers, it will frustrate your users if it clangs.

Aug 25, 2017Technology
How to Upload Files With Django

File upload works differently from simple form inputs, which can be somewhat troublesome for beginners. Here I'll show you how to handle uploads with ease.

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.