How can I check if a URL exists with Django’s validators?

I want to check in django if a URL exists and if it does I want to show something on screen, i.e.:

if URL_THAT_POINTS_TO_SOME_PDF exists 
     SHOW_SOMETHING

Solution

Edit: Please note, this is no longer valid for any version of Django above 1.5

I assume you want to check if the file actually exists, not if there is just an object (which is just a simple if statement)

First, I will recommend always looking through Django's source code because you will find some great code that you could use :)

I assume you want to do this within a template. There is no built-in template tag to validate a URL but you could essentially use that URLValidator class within a template tag to test it. Simply:

from django.core.validators import URLValidator
from django.core.exceptions import ValidationError

validate = URLValidator(verify_exists=True)
try:
    validate('http://www.somelink.com/to/my.pdf')
except ValidationError as e:
    print(e)

The URLValidator class will spit out the ValidationError when it can't open the link. It uses urllib2 to actually open the request so it's not just using basic regex checking (But it also does that.)

You can plop this into a custom template tag, which you will find out how to create in the django docs and off you go.

Hope that is a start for you.