[Pythonmac-SIG] reading text from HTML form to Python using CGI

Tue Sep 9 15:56:49 EDT 2003

On Tuesday, September 9, 2003, at 08:06  AM, Proboscis Admin wrote:

> Could you please advice. Or even basic code of what must be in the CGI 
> for it to read the form.

This might be off-topic for this list but I'll bite. I've recently 
decided to abandon PHP in favour of Python and I'm much happier! The 
only problem is optimizing your python CGI; unless you install 
something like mod_python (which is pretty old, unfortunately), it's a 
bit hard to get the performance of PHP. But I've gotten close. The 
biggest performance boost you can get if you're using a CGI is to make 
a "frozen" python binary using the tools at:

	http://www.egenix.com/files/python/mxCGIPython.html

With that python with start up instantaneously.

I've included the text of a simple CGI that should teach you a bit 
about using the high-level interface for the CGI module and a little 
bit about python too. I'm not sure in which way you were using the CGI 
module that was causing it to raise an exception; if getfirst() used as 
below cannot find the key, it returns None.

The script below works with Apple's installation of Python 2.2 in 
/usr/bin/python with OS 10.2 (you can replace the first line with #! 
/usr/bin/python, if you really want).

#!/usr/bin/env python

""" A web page/cgi that shows a menu of web pages to redirect
to, and then calls itself as the form action to redirect to
that web page.

CGI variables:
     url     - if this variable is set, the client is redirected to this.

"""

import cgi

# other stuff that's useful
import sys, os

# I didn't use this, but if you're going to join lots of strings, you 
should.
from StringIO import StringIO

# let's get the form values. we actually query these in the main 
function below.
gForm = cgi.FieldStorage()

def redirect(url):
     "Called to redirect to the given url."

     print 'Location: %s' % url
     print

     sys.exit() # exit the cgi now to make sure nothing else gets 
printed.

def print_html():
     "Called to print out html so the user can choose a url to redirect 
to."

     htmlTemplate = """
     <html>
     <head>
     <title>%(documentTitle)s</title>
     </head>

     <h1>%(documentTitle)s</h1>

     <form action="%(formAction)s" method="%(formMethod)s">

     <p>Select a web site to visit:
         <select name="url">
         <option value="http://python.org/topics/web/basic-cgi.html" 
selected>
             Basic CGI Programming in Python
         <option value="http://python.org/topics/web/">
             Web Programming in Python
         <option value="http://python.org/topics/">
             Python Topic Guides
         <option value="http://python.org/">
             python.org

         %(extraURLOptions)s
         </select>
         <input type="submit">
     </p>
     </form>

     </html>
     """

     # a dictionary of values to fill the html template with
     htmlValues = {
         'documentTitle'     : 'CGI Programming Example',
                                 # in case we're not running as a CGI, 
use foo.
         'formAction'        : 
os.path.basename(os.environ.get('SCRIPT_NAME', 'foo')),
         'formMethod'        : 'POST', # or GET.
         'extraURLOptions'   : make_option_tags_for('http://sarwat.net',
                                 'http://sarwat.net/opensource/')}

     # actually start printing html
     print "Content-Type: text/html"
     print

     print htmlTemplate % htmlValues

def make_option_tags_for(*args):
     # the *args means that args is a variable argument list. You can 
pass as many
     # arguments as you want to this function and they'll turn into this 
list.

     result = ""
     for url in args:
         result += '<option value="%s">%s\n' % (url, url)
     return result

if __name__ == '__main__':

     # get the url from the form. Use getfirst, because the cgi module 
lets us store lists
     # in the FieldStorage object as well (the other option is getlist)
     url = gForm.getfirst('url')

     if not url:
         print_html()
     else:
         redirect(url)

{sarwat khan : http://sarwat.net}