Coding style¶

Python style¶

• Please conform to the indentation style dictated in the .editorconfig file. We recommend using a text editor with EditorConfig support to avoid indentation and whitespace issues. The Python files use 4 spaces for indentation and the HTML files use 2 spaces.

• Unless otherwise specified, follow PEP 8.

  Use flake8 to check for problems in this area. Note that our setup.cfg file contains some excluded files (deprecated modules we don’t care about cleaning up and some third-party code that Django vendors) as well as some excluded errors that we don’t consider as gross violations. Remember that PEP 8 is only a guide, so respect the style of the surrounding code as a primary goal.

  An exception to PEP 8 is our rules on line lengths. Don’t limit lines of code to 79 characters if it means the code looks significantly uglier or is harder to read. We allow up to 119 characters as this is the width of GitHub code review; anything longer requires horizontal scrolling which makes review more difficult. This check is included when you run flake8. Documentation, comments, and docstrings should be wrapped at 79 characters, even though PEP 8 suggests 72.

• Utilisez 4 espaces pour l’indentation.

• Use four space hanging indentation rather than vertical alignment:

  raise AttributeError(
      'Here is a multiline error message '
      'shortened for clarity.'
  )
  

  Instead of:

  raise AttributeError('Here is a multiline error message '
                       'shortened for clarity.')
  

  This makes better use of space and avoids having to realign strings if the length of the first line changes.

• Use single quotes for strings, or a double quote if the string contains a single quote. Don’t waste time doing unrelated refactoring of existing code to conform to this style.

• Avoid use of « we » in comments, e.g. « Loop over » rather than « We loop over ».

• Use underscores, not camelCase, for variable, function and method names (i.e. poll.get_unique_voters(), not poll.getUniqueVoters()).

• Use InitialCaps for class names (or for factory functions that return classes).

• In docstrings, follow the style of existing docstrings and PEP 257.

• In tests, use assertRaisesMessage() and assertWarnsMessage() instead of assertRaises() and assertWarns() so you can check the exception or warning message. Use assertRaisesRegex() and assertWarnsRegex() only if you need regular expression matching.

• In test docstrings, state the expected behavior that each test demonstrates. Don’t include preambles such as « Tests that » or « Ensures that ».

  Reserve ticket references for obscure issues where the ticket has additional details that can’t be easily described in docstrings or comments. Include the ticket number at the end of a sentence like this:

  def test_foo():
      """
      A test docstring looks like this (#123456).
      """
      ...
  

Importations¶

• Use isort to automate import sorting using the guidelines below.

  Quick start:

  / 

  $ pip install isort
  $ isort -rc .
  

  ...\> pip install isort
  ...\> isort -rc .
  

  This runs isort recursively from your current directory, modifying any files that don’t conform to the guidelines. If you need to have imports out of order (to avoid a circular import, for example) use a comment like this:

  import module  # isort:skip
  

• Put imports in these groups: future, standard library, third-party libraries, other Django components, local Django component, try/excepts. Sort lines in each group alphabetically by the full module name. Place all import module statements before from module import objects in each section. Use absolute imports for other Django components and relative imports for local components.

• Sur chaque ligne, triez les éléments par ordre alphabétique en groupant les noms avec majuscule avant les noms avec minuscule.

• Séparez les longues lignes par des parenthèses et indentez les lignes de continuation par 4 espaces. Ajoutez une virgule finale après la dernière importation et placez la parenthèse fermante sur sa propre ligne.

  Placez une seule ligne vierge entre la dernière importation et tout code de niveau module, et placez deux lignes vierges au-dessus de la première fonction ou classe.

  Par exemple (les commentaires ne sont qu’à titre informatif) :

  django/contrib/admin/example.py¶

  # future
  from __future__ import unicode_literals
  
  # standard library
  import json
  from itertools import chain
  
  # third-party
  import bcrypt
  
  # Django
  from django.http import Http404
  from django.http.response import (
      Http404, HttpResponse, HttpResponseNotAllowed, StreamingHttpResponse,
      cookie,
  )
  
  # local Django
  from .models import LogEntry
  
  # try/except
  try:
      import yaml
  except ImportError:
      yaml = None
  
  CONSTANT = 'foo'
  
  
  class Example:
      # ...
  

• Utilisez des importations les plus directes possibles quand elles sont disponibles

  from django.views import View
  

  au lieu de

  from django.views.generic.base import View
  

Style des gabarits¶

• Dans le code des gabarits Django, placez un et un seul espace entre les accolades et le contenu des balises.

  Faites :

  {{ foo }}
  

  Ne faites pas :

  {{foo}}
  

Style des vues¶

• Dans les vues de Django, le premier paramètre d’une vue fonction devrait s’appeler request.

  Faites

  def my_view(request, foo):
      # ...
  

  Ne faites pas :

  def my_view(req, foo):
      # ...
  

Style des modèles¶

• Les noms de champs devraient être tout en minuscules, en utilisant des soulignements au lieu du StyleChameau.

  Faites

  class Person(models.Model):
      first_name = models.CharField(max_length=20)
      last_name = models.CharField(max_length=40)
  

  Ne faites pas :

  class Person(models.Model):
      FirstName = models.CharField(max_length=20)
      Last_Name = models.CharField(max_length=40)
  

• La class Meta doit apparaître après les définitions de champs, avec une seule ligne vierge séparant les champs de la définition de classe.

  Faites

  class Person(models.Model):
      first_name = models.CharField(max_length=20)
      last_name = models.CharField(max_length=40)
  
      class Meta:
          verbose_name_plural = 'people'
  

  Ne faites pas :

  class Person(models.Model):
      first_name = models.CharField(max_length=20)
      last_name = models.CharField(max_length=40)
      class Meta:
          verbose_name_plural = 'people'
  

  Ne faites pas ça non plus :

  class Person(models.Model):
      class Meta:
          verbose_name_plural = 'people'
  
      first_name = models.CharField(max_length=20)
      last_name = models.CharField(max_length=40)
  

• L’ordre des classes internes de modèles et des méthodes standards doit être le suivant (notez qu’elles ne sont pas toutes obligatoires) :

  • Tous les champs de la base de données
  • Attributs des gestionnaires personnalisés
  • class Meta
  • def __str__()
  • def save()
  • def get_absolute_url()
  • Toute autre méthode personnalisée

• Si choices est défini pour un champ de modèle, définissez chaque choix sous forme de tuple de tuples, avec un nom tout en majuscules comme attribut de classe du modèle. Exemple

  class MyModel(models.Model):
      DIRECTION_UP = 'U'
      DIRECTION_DOWN = 'D'
      DIRECTION_CHOICES = (
          (DIRECTION_UP, 'Up'),
          (DIRECTION_DOWN, 'Down'),
      )
  

Utilisation de django.conf.settings¶

Les modules ne devraient généralement pas utiliser des réglages stockés dans django.conf.settings à leur premier niveau (c’est-à-dire évalués au moment de l’importation du module). Voici pourquoi :

La configuration manuelle des réglages (qui ne dépend pas de la variable d’environnement DJANGO_SETTINGS_MODULE) est autorisée et possible comme ceci

from django.conf import settings

settings.configure({}, SOME_SETTING='foo')

However, if any setting is accessed before the settings.configure line, this will not work. (Internally, settings is a LazyObject which configures itself automatically when the settings are accessed if it has not already been configured).

So, if there is a module containing some code as follows:

from django.conf import settings
from django.urls import get_callable

default_foo_view = get_callable(settings.FOO_VIEW)

…then importing this module will cause the settings object to be configured. That means that the ability for third parties to import the module at the top level is incompatible with the ability to configure the settings object manually, or makes it very difficult in some circumstances.

Instead of the above code, a level of laziness or indirection must be used, such as django.utils.functional.LazyObject, django.utils.functional.lazy() or lambda.

Divers¶

• Marquez toutes les chaînes à traduire ; voir la documentation i18n pour plus de détails.
• Remove import statements that are no longer used when you change code. flake8 will identify these imports for you. If an unused import needs to remain for backwards-compatibility, mark the end of with # NOQA to silence the flake8 warning.
• Systematically remove all trailing whitespaces from your code as those add unnecessary bytes, add visual clutter to the patches and can also occasionally cause unnecessary merge conflicts. Some IDE’s can be configured to automatically remove them and most VCS tools can be set to highlight them in diff outputs.
• Please don’t put your name in the code you contribute. Our policy is to keep contributors” names in the AUTHORS file distributed with Django – not scattered throughout the codebase itself. Feel free to include a change to the AUTHORS file in your patch if you make more than a single trivial change.

Style JavaScript¶

Pour plus de détails sur le style de code JavaScript utilisé par Django, consultez JavaScript.