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 13, 2022Technology
How to create a timelapse video from frames

We’ll tell you how to create a video timelapse from a sequence of snapshots and provide customers with video playlists optimized for browser playback.

Jun 8, 2022Technology
How to Use MongoDB in Python: Gearheart`s Experience

In this article, we have prepared a quick tutorial on how to use MongoDB in Python and listed top ORM.

Jul 27, 2017Technology
How to Deploy Django app with AWS Elastic Beanstalk?

In this article I'll show you how to deploy Django application to AWS Beanstalk.

May 18, 2017Technology
Angular2: Development Tips and Trick

In this article we'll discuss some tricks you can use with Angular to make routing cleaner and improve SEO of your application.

Dec 1, 2016Technology
How to Use Django & PostgreSQL for Full Text Search

For any project there may be a need to use a database full-text search. We expect high speed and relevant results from this search. When we face such problem, we usually think about Solr, ElasticSearch, Sphinx, AWS CloudSearch, etc. But in this article we will talk about PostgreSQL. Starting from version 8.3, a full-text search support in PostgreSQL is available. Let's look at how it is implemented in the DBMS itself.

Sep 22, 2016Technology
Angular Form Validation

In this article, we will describe some useful scripts and directives we use with angular form validation in our projects.