[Tutor] Passing Arguments to a Remote CGI Script

[Danny Yoo]

On Fri, 13 Sep 2002 Jmllr891@cs.com wrote:

> I've been fooling around with Python and the web lately. I need to know,
> how would you pass arguments (such as a username and password) to a
> remote CGI script directly from within Python?

Hello!

We can pass information into a CGI in a few ways.  The easiest would
probably be to pass it in as part of the "query string" --- as part of the
URL that starts off with a question mark.


For example, let's say that we had a CGI running on a server, like this:

###
"""test.cgi  --- a small CGI program to show how one can pass parameters.
"""

import cgi
fs = cgi.FieldStorage()

print "Content-type: text/plain\n"
for key in fs.keys():
    print "%s = %s" % (key, fs[key].value)
###

Simple enough --- this should just echo off any parameters we send to it.



Ok, with this, we can experiment a bit with passing parameters.  If you
have a browser ready, try putting in the url of the cgi, and add to the
end of it... something like this:

    ?name=jmllr891&password=python


For example, the following url:

    http://www.decrem.com/~dyoo/test.cgi?name=dyoo&password=tutor

runs the 'test.cgi' CGI script and passes those two parameters into the
CGI.  (If you'ved noticed, lots of dynamic web sites, like amazon.com,
have weird URLs like this:  that's the passing of parameters between your
browser and the CGI's on a server.)


So all our Python program needs to do is pack all our parameter arguments
in a string, and then use the 'urllib' url-handling module to send them
off.  The urllib module has a fucntion called 'urllib.urlencode()' that
does most of the hard work:

###
import urllib

params = { 'language' : 'Python',
           'url': 'http://python.org' }
encoded_params = urllib.urlencode(params)
response = urllib.urlopen('http://www.decrem.com/~dyoo/test.cgi?%s' %
                          encoded_params)
print "here's what the CGI sent back to us: ", response.read()
###


Please feel free to ask more questions; I think I rushed certain things,
so if anything's fuzzy, we can try concentrating on those things.  I hope
this helps!