Brenton Cleeland

Slides from my presentation at MelbDjango in January 2018 on the changes to URLs in Django 2.0.

Django 2.0

• Released December, 2017
• Major features:
  • Only supports Python 3.4 and above
  • Mobile-friendly admin interface
  • Simplified URL routing syntax

---

The old way

from django.conf.urls import url

urlpatterns = [
  url(r'^articles/(?P<year>[0-9]{4})/$', views.year_archive),
]

• Required users to understand regular expressions
• Passes URL parameters as strings to your views

---

The new way

from django.urls import path

urlpatterns = [
  path('articles/<int:year>/', views.year_archive)
]

• Simpler for new users (no more regex!)
• Handles coercion into the designated type
• Can be extended with ... functions

---

And you can still regex

from django.urls import re_path

urlpatterns = [
  # support date paths: /date/2018-01-18
  re_path(r'^date/(?P<year>[0-9]{4})-(?P<month>[0-9]{2})-(?P<day>[0-9]{2})$', views.day_archive)
]

• You can use django.urls.re_path to add regex-based URLs
• (you can also just keep using the old url function)

---

The built in converters

int: Matches zero or any positive integer. Returns an int.

Old:

url(r'^posts/(?P<pk>[0-9]+)/$', views.post)

New:

path('posts/<int:pk>/', views.post)

---

The built in converters

str: Matches any non-empty string, excluding the path separator, '/'

Old:

url(r'^define/(?P<word>[^/]+)/$', views.define)

New:

path('posts/<str:word>/', views.define)

or

path('posts/<word>/', views.define)

---

The built in converters

uuid: Matches a formatted UUID.

Old:

url(r'^(?P<pk>\b[0-9a-f]{8}\b(-\b[0-9a-f]{4}\b){3}-\b[0-9a-f]{12}\b)$', views.post)

New:

path('<uuid:pk>/', views.post)

---

The built in converters

slug: Matches slugs compatible with SlugField

Old:

url(r'^posts/(?P<post_slug>[-\w]+)/$', views.post)

New:

path('posts/<slug:post_slug>/', views.post)

---

The built in converters

path: Matches any non-empty string, including the path separator, '/'.

Old:

url(r'^url/(?P<url>.+)/$', views.url_info)

New:

path('url/<path:url>', views.url_info)

---

Adding your own converter

• Register custom converters with django.urls.register_converter

  • The documentation suggests doing this in your urls.py

• register_converter takes two arguments:

  • A Converter
  • The "type name" used in the URL

---

isodate converter

import datetime
from django.urls import register_converter

class IsoDateConverter:
    regex = '\d{4}-\d{2}-\d{2}'

    def to_python(self, value):
        return datetime.datetime.strptime(value, '%Y-%m-%d').date()

    def to_url(self, value):
        return str(value)


register_converter(IsoDateConverter, 'isodate')

---

Custom conversion functions

• The result of to_python will be passed to your view
• If an exception is raised, the next URL pattern will be used
• Simple to test:

def test_isodate(self):
    response = self.client.get('/url/2018-01-18/').json()
    self.assertEqual('isodate', response['url_name'])

---

That's it!

• Follow me on Twitter: @sesh
• Talk will be on https://brntn.me
• I work at Thoughtworks now (it's great)

---

Resources

• https://docs.djangoproject.com/en/2.0/releases/2.0/
• https://docs.djangoproject.com/en/2.0/topics/http/urls/
• https://docs.djangoproject.com/en/2.0/topics/http/urls/#how-django-processes-a-request
• https://docs.djangoproject.com/en/2.0/ref/urls/#django.urls.path