** Patch added: "Handle errors from Request.finish()" https://bugs.launchpad.net/bugs/892794/+attachment/2602824/+files/avoid-request-finish-error.patch
-- You received this bug notification because you are a member of Divmod- dev, which is the registrant for nevow. https://bugs.launchpad.net/bugs/892794 Title: Nevow should handle interrupted HTTP responses Status in Divmod Nevow: New Bug description: (This is copied from the mailing list. I enclose a patch, which includes a unit test.) J.P's excellent article http://jcalderone.livejournal.com/50890.html explains how to avoid calling Request.finish() on a request after its connection was lost, because that now raises an exception. The code in the article is able to avoid calling finish() because it handles the rendering itself. The call to finish() is right there in _delayedRender. But I'm using Nevow (because it's awesome) and all that stuff is done behind the scenes, where I can't get to it. My application has a form, which uses the Post/Redirect/Get pattern (http://en.wikipedia.org/wiki/Post/Redirect/Get) to avoid double-posting. Because processing is not instant, the browser receives the HTTP header telling it to redirect before the processing has finished. When the processing finishes, the Deferred embedded in the web page fires with a value, Stan finishes flattening the page, and Nevow calls Request.finish(). By then the browser has closed the connection and sent in the GET request. So I get an error every single time. Any page that uses Deferreds and redirects will do as well. This is a completely self-contained example, to be run with twistd: from nevow import tags, inevow, loaders, appserver from nevow.rend import Page from nevow.url import URL from twisted.internet.task import deferLater from twisted.internet import reactor from twisted.application import service from twisted.application.internet import TCPServer from twisted.web import http class Redirector(Page): count = 0 message = 0 def _increment(self): self.count += 1 return self.count def slow_operation(self): return deferLater(reactor, 3, self._increment) def beforeRender(self, ctx): req = inevow.IRequest(ctx) if req.method == 'POST': oldurl = URL.fromContext(ctx) newurl = oldurl.remove('cmd') req.setResponseCode(http.SEE_OTHER) req.setHeader("Location", newurl) self.message = self.slow_operation() def render_message(self, ctx, data): return self.message docFactory = loaders.stan( tags.html[ tags.head[tags.title['Slow page']], tags.body[ tags.h1['Problem with interrupted connections'], tags.form(method='post', action='')[ tags.button(type='submit', name='cmd', value='click')[ 'Click' ] ], tags.p(render=tags.directive('message')) ] ] ) application = service.Application('Demo') site = appserver.NevowSite(Redirector()) webservice = TCPServer(8123, site) webservice.setName('WUI') webservice.setServiceParent(application) To manage notifications about this bug go to: https://bugs.launchpad.net/nevow/+bug/892794/+subscriptions -- Mailing list: https://launchpad.net/~divmod-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~divmod-dev More help : https://help.launchpad.net/ListHelp
