Multi-view URLResolver/RoutingView

[carltongibson]

DRF handles multi-renderer cases well. But it struggles when you need different logic by content type. e.g. serving a traditional HTML view requires a redirect on POST that the API views do not. We might serve RSS, say, which again needs a different view implementation. And so on.

There are some ideas for implementing this:

• DP16139 duplicate of DP8896 both looking for routing on more than the path, but with the django-hosts use-case in mind. (Middle FTW there.)
• DP16774 Backtracking URL resolver (still open) has the idea of raising a DoesNotResolve to continue through a list of views. This implemented by JKM in django-multiurl, raising ContinueResolving. Not far off but requires adjusting the views...
• Some other discussion, ref a routing view that handles inspecting the request and handing off from there. DP2784 closed pointing to mailing list discusion. Plus see also DP20479. (This last points to DP16213 proposing a ViewCollection, and mentions DRF's ViewSets — Not quite the same point but...)

Of these the routing view is the cleanest. But could it be pulled up into the URL resolver?

BaseHandler doesn't pass the request into the resolver, but it could:

    def resolve_request(self, request):
        """
        Retrieve/set the urlconf for the request. Return the view resolved,
        with its args and kwargs.
        """
        # Work out the resolver.
        if hasattr(request, 'urlconf'):
            urlconf = request.urlconf
            set_urlconf(urlconf)
            resolver = get_resolver(urlconf)
        else:
            resolver = get_resolver()
        # Resolve the view, and assign the match object back to the request.
        resolver_match = resolver.resolve(request.path_info)
        request.resolver_match = resolver_match
        return resolver_match

Is there any advantage to MultiResolver vs a suitably generic RoutingView? What does each look like?

To consider: we'd like to be able to apply middleware to parts of the site, at the URLConf level, rather than just the whole site, or individual views (to avoid putting if path_info == ... type logic in the middleware). If the box were open, how might we address that too?

[carltongibson]

Mailing list thread (with related tickets) on Adding tags to URLs.

What I'd like to do is apply middleware at the include() point, much like wrapping an individual view, but for a whole list of URLs. resolve() then returns the view callback, wrapped in the middleware to be applied.