Mailman 3 October 2009 - Twisted-web

My solution to appending slashes to resources
by Mark Wright Oct. 7, 2009

Oct. 7, 2009

(I didn't reply to my original message because the mailing list never sent it to me. Yet, I can see it at the archives here http://twistedmatrix.com/pipermail/twisted-web/2009-October/004334.html - is anyone getting these messages?) A bit of metaprogramming to the rescue. For those Resource classes that you want to append slashes automatically, this seems to work. Can anyone see any problems with this? def append_slashes(rsc_class): original_getChild = rsc_class.getChild original_render = rsc_class.render def slash_appending_getChild(self, path, request): if path == '': return self else: return original_getChild(self, path, request) def slash_appending_render(self, request): if request.prepath[-1] != '': request.redirect(request.childLink("")) return "" else: return original_render(self, request) rsc_class.getChild = slash_appending_getChild rsc_class.render = slash_appending_render rsc_class.isLeaf = False return rsc_class # test code # entering http://localhost:8080/hello should redirect to http://localhost:8080/hello/ from twisted.internet import reactor from twisted.python import log from twisted.web import server, resource, static import sys class MyPage(resource.Resource): def render_GET(self, request): return "<html><body><p>Hello World</p></body></html>" append_slashes(MyPage) log.startLogging(sys.stdout) root = resource.Resource() root.putChild("hello", MyPage()) site = server.Site(root) reactor.listenTCP(8080, site) reactor.run() -- Mark Wright markscottwright(a)gmail.com

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I can't be the only one who prefers trailing slashes on my URLs...
by markscottwright＠gmail.com Oct. 6, 2009

Oct. 6, 2009

I've got a resource that a) dynamically builds it's children using getChild and b) I'd like to have trailing slashes. It seems like a lot of work - is there a facility to do this already in twisted.web.resource.Resource? It seems like in every resource's render(), I need to do something like: def render(self, request): if request.prepath[-1] != '': request.redirect(request.childLink("")) request.finish() return "" else: return resource.Resource.render(self, request) And every getChild needs to look like this: def getChild(self, path, request): if path == '': return self elif path == 'edit': return CrudEdit() else: return None It looks like overriding this wouldn't be much better - since if I still want to use render(), the child needs to remember to call TrailingSlashResource.render(self, request) in its render() - same with getChild. Decorators need to decorate both methods as well. Is there a facility in twisted.web that does this? I'm not using nevow, which appears to just have an addSlash property on it's Page objects. Thanks all. markscottwright(a)gmail.com

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Re: [Twisted-web] [Twisted-Python] Is it necessary to utilize twisted.cred in twisted web?
by Phil Christensen Oct. 6, 2009

Oct. 6, 2009

crossposted to twisted-web(a)twistedmatrix.com, which is probably a better venue... On Oct 6, 2009, at 12:08 AM, biziap biziap wrote: > I have googled this topic and found and example in > (A) http://www.mail-archive.com/twisted-web@twistedmatrix.com/msg01796.html > well, another simpler example is > (B) http://www.mail-archive.com/twisted-web@twistedmatrix.com/msg01788.html > > My questions are: > 1. Does the approach in (A) be recommended? To generate resource > dynamically seems not efficient and not necessary for simple scenario. > Is there other way to bind twisted.cred and twisted.web together? > (except the deprecated twisted.web.guard) There's a few problems with this approach. The biggest is that it requires username/password data to be sent on every authenticated request. Another one is more of a design principle; that you shouldn't have account/permissions code inside resource display code. I violate this principle all the time ;-) The use of dynamic resource instantiation is a common idiom in twisted.web coding, though. it isn't inherently inefficient, as long as your resource objects are fairly sane. > 2. The approach in (B) which suggests that request.getSession() along > is quite enough to implement an simple authentication feature. Here > the "simple scenario" means to guard some resource with username and > password. > To do it: In a protected resource, just to check for a flag in the > session, if failure, then redirect to login page. If succeeded, render > the resource. Why shall we bother the portal, credentials, > checker,.... ? true, depending on your needs, this may be all that you need. from your description, though, it sounds like you'd be doing this authentication step in every resource you want to protect, which could become tedious (aka error-prone) in a big project. twisted.cred can seem daunting when you're just trying to protect a trivial web resource or two, but for more advanced uses like more complicated authentication levels, it's worth the time to learn. also, a big part of its real value comes when you need to support a variety of protocols and/or authentication types. -phil

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