Kivy UrlRequest called as a class - Methods not executed? -

trying experiment , build class resolving around use of urlrequest check if given url valid. turns out being bit more difficult anticipated!

the issue on_success , on_failure/error methods defined part of class never called. script throws following output (based on print commands):

http://www.google.com request sent url doesn't work 

now suspicion i´m getting return code ("none") test_connection method, , not connectionsuccess or connectionfailure. how can make call wait 1 of latter give return? suggestion welcome. thanks.

from kivy.app import app kivy.uix.floatlayout import floatlayout kivy.network.urlrequest import urlrequest  class webexplorer():           def test_connection(self, path):         self.path = path         print (self.path)         req = urlrequest(self.path,on_failure=self.connectionfailure,on_error=self.connectionfailure,on_success=self.connectionsuccess)         print ("request sent")      def connectionsuccess(self,*args):         print ("connectionsuccess")         return 0      def connectionfailure(self,*args):         print ("connectionfailure")         return 1   class mainscreen(floatlayout):     def __init__(self, **kwargs):         super(mainscreen, self).__init__(**kwargs)         self.address = 'http://www.google.com'          if webexplorer().test_connection(self.address) == 0:             print ("url works")         else:             print ("url doesn't work")  class app(app):     def build(self):         return mainscreen()   if __name__ == "__main__":      app().run()  

update 2016-09-27 changed code , have spent hours on trying figure out problem. first code:

from kivy.app import app kivy.uix.floatlayout import floatlayout kivy.network.urlrequest import urlrequest  class webexplorer():      def test_connection(self, path):         self.path = path         req = urlrequest(self.path,on_failure=self.connectionfailure,on_error=self.connectionfailure,on_success=self.connectionsuccess)         req.wait()         return (self._return_value)      def connectionsuccess(self, req, results):         print ("success")         self._return_value = [0,results]      def connectionfailure(self, req, results):         print ("failure")         self._return_value = [1,results]   class mainscreen(floatlayout):     def __init__(self, **kwargs):         super(mainscreen, self).__init__(**kwargs)         self.urltest = ['http://www.ikea.com/','https://www.google.com','https://www.sdfwrgaeh.com']         url in self.urltest:             self.returncode = webexplorer().test_connection(url)             if self.returncode[0] == 0:                 print ("correct url")             else:                 print ("wrong url")  class app(app):     def build(self):         return mainscreen()  if __name__ == "__main__":      app().run()  

why 3 urls? because 1 "correct" (ikea), 1 redirect (google) , 1 bogus. turns out, code works first 1 only. req.wait doesn't work when result failure/error (btw have 0 idea what's difference between these two).

so question how make req.wait process failure, alternatively how exit class correct error code. considered clock.schedule_interval periodically check status, ut since event methods not executed when url incorrect, have set variales -_-

urlrequest asynchron, means actual request processed in background while application proceeds. functions on_failure etc. callbacks, i.e. called when request done - means return value "lost". return value indeed test_connection function.

you mentioned on mailing list want make call root url, processing on , issue new requests suburls depending on content , user interaction.

the following should provide skeleton trying do.

class webexplorer      def __init__(self, gui):         self._visited_urls = [] # prevent endless redirect loops         self._visiting = set() # check if still doing         self.gui = gui # used display buttons in process_result      def get_url(self, url):         self._visited_urls.append(url)         self._visiting.add(url)         urlrequest(url,              on_success=self.process_result,             on_failure=self.failure,             on_error=self.failure, # difference between failure , error?             on_redirect=self.redirect)      def redirect(self, req):         self._visiting.discard(req.url)         self.get_url(req.req_headers["location"]) # check if correct handling of 3xx      def process_result(self, req):         self._visiting.discard(req.url)         #todo process body extract urls want visit          box = boxlayout()         url in urls_you_want_to_visit:             button = button()             button.text = url             # i'm not sure if following works due scoping oddities             # if - no matter button pressed - same url called             # line @ fault             button.bind(on_press=lambda: self.get_url(url))              box.add_widget(button)          gui.add_widget(box) 

of course there still lot improve. it's not tested can contain bugs.