38 lines
1.9 KiB
Markdown
38 lines
1.9 KiB
Markdown
|
---
|
|||
|
|
layout: post
|
|||
|
|
title: "@ParamConverter à la Django"
|
|||
|
|
date: 2015-06-07 20:14:32+02:00
|
|||
|
|
tags: [python, django]
|
|||
|
|
published: true
|
|||
|
|
author:
|
|||
|
|
name: Gergely Polonkai
|
|||
|
|
email: gergely@polonkai.eu
|
|||
|
|
---
|
|||
|
|
One thing I really miss from [Django](https://www.djangoproject.com/)
|
|||
|
|
is [Symfony](http://symfony.com)’s
|
|||
|
|
[@ParamConverter](http://symfony.com/doc/current/bundles/SensioFrameworkExtraBundle/annotations/converters.html). It
|
|||
|
|
made my life so much easier while developing with Symfony. In Django,
|
|||
|
|
of course, there is
|
|||
|
|
[get_object_or_404](https://docs.djangoproject.com/en/dev/topics/http/shortcuts/#get-object-or-404),
|
|||
|
|
For example, in one of my projects I had a view that had to resolve 6
|
|||
|
|
objects from the URL, and writing `get_object_or_404` six times is not
|
|||
|
|
what a programmer likes to do. A quick Google search gave me one
|
|||
|
|
[usable result](http://openclassrooms.com/forum/sujet/middleware-django-genre-paramconverter-doctrine)
|
|||
|
|
(in French), but it was very generalized that I cannot always
|
|||
|
|
use. Also, it was using a middleware, which may introduce performance
|
|||
|
|
issues sometimes<sup>[citation needed]</sup>. So I decided to go with decorators, and at the end, I came up with this:
|
|||
|
|
|
|||
|
|
{% gist gergelypolonkai/498a32297f39b4960ad7 helper.py %}
|
|||
|
|
|
|||
|
|
Now I can decorate my views, either class or function based, with
|
|||
|
|
`@convert_params(User, (Article, 'aid'), (Paragraph, None, 'pid'),
|
|||
|
|
(AnotherObject, None, None, 'obj'))` and all the magic happens in the
|
|||
|
|
background. The `user_id` parameter passed to my function will be
|
|||
|
|
popped off, and be resolved against the `User` model by using the `id`
|
|||
|
|
field; the result is put in the new `user` parameter. For Article, the
|
|||
|
|
`aid` parameter will be matched against the `id` field of the
|
|||
|
|
`Article` model putting the result into `article`, and finally, the
|
|||
|
|
`another_object_id` will be matched against the `id` field of the
|
|||
|
|
`AnotherObject` model, but in this case, the result is passed to the
|
|||
|
|
original function as `obj`.
|