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
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.

Jul 21, 2022Technology
Codemirror: unit-testing codemirror react components

One of our recent projects includes the functionality of an inline code editor. This code editor needed to be highly extensible and have custom features. To address this, we chose Codemirror v6 due to its peculiar architecture - it is highly customizable, and all the additional features are provided into codemirror engine as Extension objects.

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.

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.

May 12, 2010Technology
Twitter API, OAuth and decorators

In my current project I had a task to use twitter API. Twitter uses OAuth for authentication, which is pretty dreary. To avoid fiddling with it all the time, I've moved authentication to decorator. If key is available - nothing happens, just view is launched as usual. It's convenient that there's no need for additional twitter settings in user profile. Code is in article.