如何获取重定向网址？

Question

I am using urllib.request to perform a sequence of http calls in python 3.6. I need to retrieve the value of a 302 http redirect that is returned in response to a urllib.request.urlopen call like so...

import urllib.request

... many previous http calls ...

post_data = {'foo': 'bar', 'some': 'otherdata'}
encoded = urllib.parse.urlencode(post_data).encode('utf-8')
req = urllib.request.Request('https://some-url', encoded)
redirected_url = urllib.request.urlopen(req).geturl()

I get an error like...

urllib.error.HTTPError: HTTP Error 302: Found - Redirection to url 'gibberish://login_callback?code=ABCD......' is not allowed

What I need is to actually get the url that is being returned in the 302 as the .geturl() method should provide, but instead I get an error.

Please no answers like "Hey use this other library that I'm super into right now" as we've spent a long time building this script using urllib2 and we have very little python knowledge.

Thanks for your help.

Answer 1

If you dont want to use the requests library (which is almost part of the core libs at this point), you need to write a custom HTTPRedirectHandler using urllib2.

import urllib2

class CustomHTTPRedirectHandler(urllib2.HTTPRedirectHandler):
    def http_error_302(self, req, fp, code, msg, headers):
        ### DO YOUR STUFF HERE
        return urllib2.HTTPRedirectHandler.http_error_302(self, req, fp, code, msg, headers)

    http_error_301 = http_error_303 = http_error_307 = http_error_302

opener = urllib2.build_opener(CustomHTTPRedirectHandler)
post_data = {'foo': 'bar', 'some': 'otherdata'}
encoded = urllib.parse.urlencode(post_data).encode('utf-8')
req = urllib.request.Request('https://some-url', encoded)
opener.urlopen(req)