Django 2.0 path error ?: (2_0.W001) has a route that contains '(?P<', begins with a '^', or ends with a '$'

I'm trying to create the back-end code for a music application on my website.

I have created the correct view in my views.py file (in the correct directory) as shown below:

def detail(request, album_id):
    return HttpResponse("<h1>Details for Album ID:" + str(album_id) + "</h1>")

However, when creating the URL or path for this (shown below)

#/music/71/ (pk)
path(r'^(?P<album_id>[0-9])/$', views.detail, name='detail'),

I am experiencing a warning on my terminal stating:

> > ?: (2_0.W001) Your URL pattern '^(?P<album_id>[0-9])/$' > [name='detail'] has a route that contains '(?P<', begins with a '^', > or ends with a '$'. This was likely an oversight when migrating to > django.urls.path(). > And whenever the /music/ (for which the path works) is followed by a number, such as /music/1 (which is what I want to be able to do) the page cannot be found and the terminal gives the above warning.

The new path() syntax in Django 2.0 does not use regular expressions. You want something like:

path('<int:album_id>/', views.detail, name='detail'),

If you want to use a regular expression, you can use re_path().

re_path(r'^(?P<album_id>[0-9])/$', views.detail, name='detail'),

The old url() still works and is now an alias to re_path, but it is likely to be deprecated in future.

url(r'^(?P<album_id>[0-9])/$', views.detail, name='detail'),

Just to add to what @alasdair mentioned, I added re_path as part of the include and it works fine. Here is an example

Add re_path to your import (for django 2.0)

from django.urls import path, re_path

urlpatterns = [
    path('admin/', admin.site.urls),
    re_path(r'^$', home, name='home'),

]

Instead of using 're_path' you can also use ''(empty string) as the first argument of your path(). I have used it and it worked for me.

urlpatterns = [
    path('admin/', admin.site.urls),
    path('',views.index,name='index'),
]

If it doesn't work add this code to yoursite\urls.py inside urlpatterns:

path('music/<int:album_id>/', views.detail, name="detail"),

Use an empty string '' instead of '/' or r'^$'. It works like a charm. Code is as below:

from django.urls import path, re_path

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', home, name='home'),
]

url() is deprecated in newer version of django. So instead of using url use re_path() in your urls file as follows:

from django.urls import path, re_path
from . import views

urlpatterns = [
    #url(r'^(?P<album_id>[0-9]+)/$', views.detail, name='detail'),
    path('', views.index, name='index'),
    re_path(r'^(?P<album_id>[0-9])/$', views.detail, name='detail'),
]

In django 2.0 version primary key write this way...

urls.py

from django.urls import path

from . import views


urlpatterns = [
    path('', views.course_list),
    path('<int:pk>/', views.course_detail),
]