I’m creating an app in which many urls are using a pattern like /foo/bar/<object_id>/<object_name_slug>/, like many applications (SO included), which is itself a straightforward pattern to implement. However, I don’t want to just blindly ignore the contents of the slug field and open the app up to stupid stuff like people distributing a doctored URL (e.g. the recently popular http://www.independent.co.uk/life-style/food-and-drink/utter-PR-fiction-but-people-love-this-shit-so-fuck-it-lets-just-print-it-2269573.html).
My plan is to validate the slug an issue a redirect to the correct URL if someone reaches a page via a bad slug (again, like SO). This would be trivial to implement in the view, but since this will be a pattern used on many views, I’d like to factor it out into something reusable–probably a decorator or a middleware.
What’s the best way to do this? Could a decorator determine which url pattern was matched by a particular request so that it could generate a reverse if necessary?
Thanks for the ideas.
You could use middleware for this. Cross-check the Entry id (let’s just suppose you use the Entry model for content. The ID in the URL you mention would be 2269573 for example) with its slug (supposing your Entry model has a slug field of course). If the slug is incorrect, just redirect to the correct page.
In order to do this, create a class, and give it the process_request method. Then add this class to your settings’ MIDDLEWARE_CLASSES.
The process_request takes a “request” parameter (a HttpRequest object), and this object has a path attribute that will give you the URL that was requested.
Based on that URL you can define the actions to be undertaken.
The method of your middleware class should return None or a HttpRequest object. The latter can be a django.http.HttpResponseRedirect instance, meaning you can redirect to the correct URL (thereby ignoring the incorrect slug).