how to check if the urllib2 follow a redirect?

Question

I've write this function:

def download_mp3(url,name):
        opener1 = urllib2.build_opener()
        page1 = opener1.open(url)
        mp3 = page1.read()
        filename = name+'.mp3'
        fout = open(filename, 'wb')
        fout.write(mp3)
        fout.close()

This function take an url and a name both as string. Then will download and save an mp3 from the url with the name of the variable name.

the url is in the form http://site/download.php?id=xxxx where xxxx is the id of an mp3

if this id does not exist the site redirects me to another page.

So, the question is: how Can I check if this id exist? I've tried to check if the url exist with a function like this:

def checkUrl(url):
    p = urlparse(url)
    conn = httplib.HTTPConnection(p.netloc)
    conn.request('HEAD', p.path)
    resp = conn.getresponse()
    return resp.status < 400

But it's seems not working..

Thank you

Answer 1

Something like this, and check code:

import urllib2, urllib

class NoRedirectHandler(urllib2.HTTPRedirectHandler):
    def http_error_302(self, req, fp, code, msg, headers):
        infourl = urllib.addinfourl(fp, headers, req.get_full_url())
        infourl.status = code
        infourl.code = code
        return infourl
    http_error_300 = http_error_302
    http_error_301 = http_error_302
    http_error_303 = http_error_302
    http_error_307 = http_error_302

opener = urllib2.build_opener(NoRedirectHandler())
urllib2.install_opener(opener)
response = urllib2.urlopen('http://google.com')
if response.code in (300, 301, 302, 303, 307):
    print('redirect')

Answer 2

My answer to this looked like

req = urllib2.Request(url)
try:
   response = urllib2.urlopen(url)
except urllib2.HTTPError as e:
   # Do something about it
   raise HoustonWeHaveAProblem
else:
   if response.url != url:
       print 'We have redirected!'