User:Eleanorg/1.2/Forbidden Pixels/Receiving URL where data is hosted: Difference between revisions

Revision as of 14:46, 26 March 2012

The site will need to ask participants for the URL of the pixel data they're hosting.This is my first time doing form processing in python: the html form asks for the url; it passes it to a simple script. Next step is for that script to add it to the list of URLs, and to check whether there is a string there matching the regex.

URL input form

<!DOCTYPE html>
<html>
  <head>
    <title>A form talking to a python script</title>
    <style type="text/css">
    </style>
  </head>
  
<body>

  <form action="form.cgi" name="inputForm">  <!--pushes form input to form.py script -->
    Paste url: 
    <input name="url">
    <input type="submit">

  </form>
</body>

</html>

Basic Python script grabbing URL submitted

Saved as .cgi within cgi-bin on server.

#!/usr/bin/python

import cgi
import cgitb; cgitb.enable() #what do these do?



htmlHeader = """<!DOCTYPE html>
<html>
  <head>
    <title>A form talking to a python script</title>
    <style type="text/css">
    </style>
  </head>
  <body>"""

print "Content-Type: text/html" //important - won't print in browser without these 2 lines
print 
print htmlHeader

form =  cgi.FieldStorage()	//Grabs whatever input comes from form
url = form['url'].value		// assigns form's url field input to var 'url'
print url
 
print """
  </body>
</html>"""

Python script grabbing inputted URL then scraping it

#!/usr/bin/python
#-*- coding:utf-8 -*-

import cgi, re, urllib2
import cgitb; cgitb.enable()

 
# scrapes pixel data string from a URL submitted by user in an html form; assigns the result to appropriate variables.
 

#------------- get URL from input form -------------------#

form = cgi.FieldStorage()		# Grabs whatever input comes from form
url = form['url'].value			# assigns form's url field input to var 'url'

#------------- scrape webpage----------------------------#

text = urllib2.urlopen(url).read()	# reads page at the specified URL

 
#-------------- extract the string with regex------------#

# string is in format: 
# Pixel position:500.001; Color:rgba(222,221,217,1)
 
for x in re.findall(r"Pixel position:(\d\d\d).(\d\d\d)\;\ Color:(rgba\(.*\))", text):
    match = str(x)    # only matches what is within capture parentheses. How to match whole string, even when bits within it are captured?
    xPos = str(x[0])  
    yPos = str(x[1])
    color= str(x[2])           
 
#-------------- print match -----------------------------#

htmlHeader = """<!DOCTYPE html>
<html>
  <head>
    <title>A form talking to a python script</title>
    <style type="text/css">
    </style>
  </head>
  <body>"""

print "Content-Type: text/html"
print 
print htmlHeader
 
if xPos:
  print 
  print "x position is: " + xPos + "<br />"
  print "y position is: " + yPos + "<br />"
  print "color is: " + color
else:					# not working - how to avoid 'match is undefined' error if regex fails to match anything?
  print "this pixel is not currently hosted"
 


print """
  </body>
</html>"""