Chap10/cgi-bin/friendsC3.py

#!/usr/bin/env python3

import cgi
from urllib.parse import quote_plus

header = 'Content-Type: text/html\n\n'
url = '/cgi-bin/friendsC.py'

errhtml = '''<html><head><title>
Friends CGI Demo</title></head>
<body><h3>Error</h3>
<b>%s</b><p>
<form><input type=button value=Back
onclick="window.history.back()"></form>
</body></html>'''

def showError(error_str):
    print(header + errhtml % error_str)

formhtml = '''<html><head><title>
Friends CGI Demo</title></head>
<body><h3>Friends list for: <i>%s</i></h3>
<form action="%s">
<b>Enter your Name: </b>
<input type=hidden name=action value=edit>
<input type=text name=person value="%s" size=15>
<p><b>How many friends do you have?</b>
%s
<p><input type=submit></form></body></html>'''

fradio = '<input type=radio name=howmany value="%s" %s> %s\n'

def showForm(who, howmany):
    friends = []
    for i in (0, 10, 25, 50, 100):
        checked = ''
        if str(i) == howmany:
            checked = 'checked'
        friends.append(fradio % (str(i), checked, str(i)))
    print('%s%s' % (header, formhtml % (
        who, url, who, ''.join(friends))))

reshtml = '''<html><head><title>
Friends CGI Demo</title></head>
<body><h3>Friends list for: <i>%s</i></h3>
Your name is: <b>%s</b><p>
You have <b>%s</b> friends.
<p>Click <a href="%s">here</a> to edit your data again.
</body></html>'''

def doResults(who, howmany):
    newurl = url + '?action=reedit&person=%s&howmany=%s'%\
        (quote_plus(who), howmany)
    print(header + reshtml % (who, who, howmany, newurl))

def process():
    error = ''
    form = cgi.FieldStorage()

    if 'person' in form:
        who = form['person'].value.title()
    else:
        who = 'New User'
    
    if 'howmany' in form:
        howmany = form['howmany'].value
    else:
        if 'action' in form and \
            form['action'].value == 'edit':
            error = 'Please select number of friends.'
        else:
            howmany = 0
    
    if not error:
        if 'action' in form and \
            form['action'].value != 'reedit':
            doResults(who, howmany)
        else:
            showForm(who, howmany)
    else:
        showError(error)

if __name__ == '__main__':
    process()