Django - Forms - What does (?P<pk>\d+)/$ signify?

user_8892765 0
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I am new to django. I was creating forms in django with the help of an online tutorial. I didnot understand a line in the urls.py file. Can someone explain what exactly it means?

from django.conf.urls import url
from . import views
from . views import BlogListView, BlogDetailView, BlogCreateView

urlpatterns = [
    url(r'^$', views.BlogListView.as_view(), name='post_list'),
    url(r'^post/(?P<pk>\d+)/$', BlogDetailView.as_view(), name='post-detail'),
    url(r'^post/new/$', BlogCreateView.as_view(), name='post_new'),
    url(r'^post/(?P<pk>\d+)/edit/$', BlogUpdateView.as_view(), name='post_edit'),
]

I did not understand the following line:

url(r'^post/(?P<pk>\d+)/$'

What does (?P<pk>\d+)/$ signify? Help please

forms django python
2 Answers

It is a regular expression, which is matched against the actual URL

Here r'' specifies that the string is a raw string. '^' signifies the start, and $ marks the end.

Now 'pk' (when inside <>) stands for a primary key. A primary key can be anything eg. it can be a string, number etc. A primary key is used to differentiate different columns of a table.

Here it is written

<pk>\d+

\d matches [0-9] and other digit characters.

'+' signifies that there must be at least 1 or more digits in the number

So,

.../posts/1 is valid

.../posts/1234 is valid

.../posts/ is not valid since there must be at least 1 digit in the number

Now this number is sent as an argument to BlogListView and you run you desired operations with this primary key

user_68537910

your BlogDetailView must be having 'id' as an parameter to capture blog post to be updated

this will capture 'id' of selected blog post and pass it to BlogDetailView

url(r'^post/(?P<pk>\d+)/$'

eg: for url: http://localhost:8000/post/2 2 will be captured and will be passed as an 'id' on to BlogDetailView

user_43367020
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