Handling and fixing a migrated page batch call error from the Facebook graph API. Tests included. Ver verbose. Supports : http://marc-w.com/editorial/parsing-facebook-gotcha/

fix_facebook_migration.py

#!/usr/bin/env python
# marc-w.com
def fix_facebook_migration(link=False,error_message=False):
    '''
    Fix a batch call for Facebook page ID information
    @param link : string, the failed link
    @param error_message : string, the 'error' message string returned from facebook
    @return : int on fail, new link on fix.
    '''
    # validate
    if not link or not error_message :
        return 1
    # split link once
    split1 =  link.split('?ids=',2) # grab the IDs
    left = split1[0]+"=" # save for later
    # split link twice
    try : 
        split2 = split1[1].split('&',2)
    except :
        return 2
    right = "&"+split2[1] # save for later
    ids = split2[0].split(',') # map to list
    try : # cast strings to ints in list
        ids = map(int, ids)
    except : 
        # error str type ints expected
        return 3
    # process error message returned from Facebook 
    err = error_message.split(' ') # word chunks
    # pull out the 2 ints per the formatting of the FB error
    # beware that the FB error can change at any point in time
    # this could lead to infinite loops amd bad mojo
    fix = [] # init
    for e in err :
        if "." in e : # period going to get you
            e = e.split('.', 2)[0] # fixed
        try : # when int
            fix.append(int(e))
        except :
            continue
    # intersect lists
    r = filter(set(ids).__contains__, fix)
    # swap bad into for migrated id in list
    if len(r) == 1 : # we expect one match
        index =  ids.index(r[0])
        ids.pop(index)
        ids.append(fix[1])
    else :
        # not fixed, log this and investigate
        # do not return original link, can lead to infinite loop
        # feeding garbage back into system
        return 4
    # format the fix
    ids =  ','.join(str(elem) for elem in ids)
    # build new link
    new_link = left+ids+right # right var may be bad (expired token). Address as needed
    # if this is run in realtime the access token should still be valid
    # other error handling should pick up on bad token attempts
    return new_link

########################
# Unit Test
########################
'''
example error message from Facebook, the message part is sent into our function
{
   "error": {
      "message": "(#21) Page ID 5701733149 was migrated to page ID 6687752570.  Please update your API calls to the new ID",
      "type": "OAuthException",
      "code": 21
   }
}
'''

########################
# Unit Test : Passing
########################
link = 'https://graph.facebook.com/?ids=20531316728,6191007822,5701733149&junk'
error_msg = '(#21) Page ID 5701733149 was migrated to page ID 6687752570.  Please update your API calls to the new ID'
new_link = fix_facebook_migration(link, error_msg)

print "Passing Test :"
print 'Error Message : '+error_msg
print 'Link : '+link
print 'Result : '+str(new_link)
print "\r\n"

########################
# Unit Test : Fail 1
########################
link = ''
error_msg = '(#21) Page ID 5701733149 was migrated to page ID 6687752570.  Please update your API calls to the new ID'
new_link = fix_facebook_migration(link,error_msg)

print "Failing Test 1 : empty link"
print 'Error Message : '+error_msg
print 'Link : '+link
print 'Result : '+str(new_link)
print "\r\n"

########################
# Unit Test : Fail 2
########################
link = 'sdklfjhg'
error_msg = '(#21) Page ID 5701733149 was migrated to page ID 6687752570.  Please update your API calls to the new ID'
new_link = fix_facebook_migration(link,error_msg)

print "Failing Test 2 : bad link data"
print 'Error Message : '+error_msg
print 'Link : '+link
print 'Result : '+str(new_link)
print "\r\n"

########################
# Unit Test : Fail 3
########################
link = 'sdklfjhg?ids=fsddkjhsdf&'
error_msg = '(#21) Page ID 5701733149 was migrated to page ID 6687752570.  Please update your API calls to the new ID'
new_link = fix_facebook_migration(link,error_msg)

print "Failing Test 3 : spoofed link format, bad data"
print 'Error Message : '+error_msg
print 'Link : '+link
print 'Result : '+str(new_link)
print "\r\n"

########################
# Unit Test : Fail 4a
########################
link = 'https://graph.facebook.com/?ids=20531316728,6191007822,999&junk'
error_msg = '(#21) Page ID 5701733149 was migrated to page ID 6687752570.  Please update your API calls to the new ID'
new_link = fix_facebook_migration(link,error_msg)

print "Failing Test 4 : edited link, no intersection"
print 'Error Message : '+error_msg
print 'Link : '+link
print 'Result : '+str(new_link)
print "\r\n"

########################
# Unit Test : Fail 4b
########################
link = 'https://graph.facebook.com/?ids=20531316728,6191007822,999&junk'
error_msg = '(#21) Page ID 5701733149 was migrated to page ID   Please update your API calls to the new ID'
new_link = fix_facebook_migration(link,error_msg)

print "Failing Test 4b : missing key data from error message"
print 'Error Message : '+error_msg
print 'Link : '+link
print 'Result : '+str(new_link)
print "\r\n"