Exit a while loop, when a certain string doesn't appear in Python

Question

I have a program which fetches an xml sheet from a url. There is a lot of data on this xml, as a result I can only see 2500 'profiles' if you will at a time.

In these xml profiles, i require the program to pull out each users ID number which is a 8 digit code. I also require the program to pull out the url to the next 2500 profiles which i did by using the endswith() function.

My problem is in the last page of data there is no link to match with and i require the loop to stop while also pulling the final set of ID's

Here is what i have so far:

myURL = 'blah'

while myUrl is not '':
    info = request.get(myUrl)

Convert it to a list of strings

    end_of_new_link = "thingy"
    for link in list
        if link.endswith(end_of_new_link)
            myUrl = link

I format the link so i can use it on the next iteration of the while loop

     elif link.startswith(IDNUMBER)
          listIDs.append(link)

Is there a way i can set the variable myUrl to empty string to exit the while loop or is my logic all wrong here

You should parse the XML so you can properly read it: http://stackoverflow.com/questions/1912434/how-do-i-parse-xml-in-python — kponz, Nov 17 '15 at 17:25

Shashank · Accepted Answer · 2015-11-17T18:11:41.707

I think the simplest way is to have two variables instead of one.

lastUrl, nextUrl = None, 'blah'

while nextUrl != lastUrl:
    # url gets consumed and becomes "old"
    info, lastUrl = request.get(nextUrl), nextUrl

Later on...

end_of_new_link = "thingy"
for link in list
    if link.endswith(end_of_new_link)
        nextUrl = link # now it's different so the loop will continue

Of course, you could make this unnecessarily abstract if you wanted to and have a wrapper object that marks if its encapsulated data has changed (or simply has been set) since the last read.

Exit a while loop, when a certain string doesn't appear in Python

1 Answers1