Hello Web - simplest web app in python

pmasiar · 12:55 AM

Someone complained that Python web app tutorials are harder than PHP. So I created these two simple python apps to help you started.

I assume you have cgi-enabled directory.

UPDATE 1: Find your python first. In terminal, type 'which python'.

Then change first line of following scripts according where your python is: /usr/bin/python or /usr/local/bin/python or whatever you have.
(end update1)

Simplest one (3 lines): place it in CGI-enabled directory, make executable by web user (or anybody, or all):

Code:

#!/usr/bin/python
import cgi
cgi.test()

It will print your CGI environment variables and you can be sure all is OK. If not, error is in your web server settings. Also, make sure that apache can read/execute this script: ie. make ir readable/executable by all.

More complicated (35 lines including 13 lines of HTML template), but still simple:

Code:

#!/usr/bin/python
import cgi
import cgitb; cgitb.enable()
import os

##---CONSTANTS -------
BGCOLOR = '#f0f0f0'

##---TEMPLATES ----------------------------------------------------
HTML = """content-type: text/html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><title>%(TITLE)s</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head><body bgcolor="%(COLOR)s"><h1>%(TITLE)s</h1>
    <h2>Hello %(NAME)s</h2>
    <hr /><h2> Who are you?</h2>
    <form action="%(SCRIPT_NAME)s" method="POST" enctype="multipart/form-data">
        <input name="person_name" type="text" size="40"><br />
        <input name="submit" type="submit" value="Try">
    </form>
</body></html>"""

def main():
    FORM = cgi.FieldStorage()
    person = FORM.getfirst('person_name')
    if not person:
        person = '(Nobody yet)'
    next_script = os.environ['SCRIPT_NAME'] # name of this script: it submits to self

    print HTML % dict(TITLE='Hello Web!', NAME=person, 
        SCRIPT_NAME=next_script, COLOR=BGCOLOR)

# idiomatic start of the main() program
if __name__ == '__main__': main()

It will ask for name, and after hitting submit, prints it in the page and asks for more. If you have this running, you are on the way.

Good luck!

gummibaerchen · 09:38 PM

Ohh, noone should use CGI in the way you offered.
Maybe a quick start, but not a good one.

That's as lame as PHP + HTML.

A Python Web-Application should be written after WSGI norms.

http://en.wikipedia.org/wiki/WSGI

Then their may be and interface for CGI if nothing better, as mod_python for example, is available.

Ok, WSGI looks harder than PHP + HTML, but in the end it's much better than pure CGI programming.

But considering, that you just want to be simple, you're damn right

It's simple, but not nice.

I think you can do a lot better, but maybe for newcomers it's nice, as they want a quick result. But I wouldn't recommend this way.

pmasiar

Quote:

Originally Posted by gummibaerchen

Ohh, noone should use CGI in the way you offered.
...
But considering, that you just want to be simple, you're damn right

It's simple, but not nice.

I think you can do a lot better, but maybe for newcomers it's nice, as they want a quick result. But I wouldn't recommend this way.

Agree with you 100%. We can do better - after learning basics.

My first goal was to test CGI is configuration, 3 line script is good enough, and if it does NOT work, your WSGI/mod_python goodness will not work either, it just will be LESS obvious what is wrong.

I am in process with one python beginner to sorting out why 1st example fails (she is on shared hosting) - some misconfigured CGI.

Second example was to show interactiive component without confusing beginner with templating system.

My 3rd example was supposed to use simples templating (htmltmpl) with the same template and multi-line string in 2nd example but I run out of time

gummibaerchen

Yeah, you're totally right.

Maybe you should extend your 2 Examples with an interactive one, that may interested more people.

For example http://example.com/cgi-bin/sqrt.py/81
And the output is

Code:

<h1>The Squareroot of 81 is 9</h1>

lazka

http://webpython.codepoint.net/mod_p...er_hello_world

maddog39

I finally got these two examples working, and here they are.

http://www.dx-h.com/cgi-bin/cgitest.py - Example 1
http://www.dx-h.com/cgi-bin/cgitest2.py - Example 2

gummibaerchen

Quote:

Originally Posted by maddog39

I finally got these two examples working, and here they are.

http://www.dx-h.com/cgi-bin/cgitest.py - Example 1
http://www.dx-h.com/cgi-bin/cgitest2.py - Example 2

Example 1 isn't working for me

Would you pls also show the source? That may be interesting

pmasiar

Quote:

Originally Posted by gummibaerchen

Example 1 isn't working for me

Would you pls also show the source? That may be interesting

Both examples work for me as supposed. Good job! Source code is in #1 - parent posting.

gummibaerchen

Quote:

Originally Posted by pmasiar

Both examples work for me as supposed. Good job! Source code is in #1 - parent posting.

http://www.dx-h.com/cgi-bin/cgitest.py - Example 1

That one gives me a long list of errors

pmasiar

Quote:

Originally Posted by gummibaerchen

Example 1....gives me a long list of errors

They are not errors - cgi.test() is supposed to print all environment variables, and it does exactly that. How hard can be to understand program 3 lines long with just one library call? Sometimes even that is not easy

January 5th, 2007	#1
pmasiar Day Old Decaf Join Date: Jun 2006 Location: CT, USA Beans: 5,268 Ubuntu 6.10 Edgy	Hello Web - 2 simple web apps in python (3 lines and 35 lines) Someone complained that Python web app tutorials are harder than PHP. So I created these two simple python apps to help you started. I assume you have cgi-enabled directory. UPDATE 1: Find your python first. In terminal, type 'which python'. Then change first line of following scripts according where your python is: /usr/bin/python or /usr/local/bin/python or whatever you have. (end update1) Simplest one (3 lines): place it in CGI-enabled directory, make executable by web user (or anybody, or all): Code: #!/usr/bin/python import cgi cgi.test() It will print your CGI environment variables and you can be sure all is OK. If not, error is in your web server settings. Also, make sure that apache can read/execute this script: ie. make ir readable/executable by all. More complicated (35 lines including 13 lines of HTML template), but still simple: Code: #!/usr/bin/python import cgi import cgitb; cgitb.enable() import os ##---CONSTANTS ------- BGCOLOR = '#f0f0f0' ##---TEMPLATES ---------------------------------------------------- HTML = """content-type: text/html <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><title>%(TITLE)s</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> </head><body bgcolor="%(COLOR)s"><h1>%(TITLE)s</h1> <h2>Hello %(NAME)s</h2> <hr /><h2> Who are you?</h2> <form action="%(SCRIPT_NAME)s" method="POST" enctype="multipart/form-data"> <input name="person_name" type="text" size="40"><br /> <input name="submit" type="submit" value="Try"> </form> </body></html>""" def main(): FORM = cgi.FieldStorage() person = FORM.getfirst('person_name') if not person: person = '(Nobody yet)' next_script = os.environ['SCRIPT_NAME'] # name of this script: it submits to self print HTML % dict(TITLE='Hello Web!', NAME=person, SCRIPT_NAME=next_script, COLOR=BGCOLOR) # idiomatic start of the main() program if __name__ == '__main__': main() It will ask for name, and after hitting submit, prints it in the page and asks for more. If you have this running, you are on the way. Good luck! Last edited by pmasiar; January 6th, 2007 at 12:55 AM..

January 5th, 2007	#2
gummibaerchen Gee! These Aren't Roasted! Join Date: Oct 2006 Beans: 152 Ubuntu 6.10 Edgy	Re: Hello Web - simplest web app in python Ohh, noone should use CGI in the way you offered. Maybe a quick start, but not a good one. That's as lame as PHP + HTML. A Python Web-Application should be written after WSGI norms. http://en.wikipedia.org/wiki/WSGI Then their may be and interface for CGI if nothing better, as mod_python for example, is available. Ok, WSGI looks harder than PHP + HTML, but in the end it's much better than pure CGI programming. But considering, that you just want to be simple, you're damn right It's simple, but not nice. I think you can do a lot better, but maybe for newcomers it's nice, as they want a quick result. But I wouldn't recommend this way. __________________ Edgy Eft Packages: Glade-3 3.1.4, Geany 0.10, Banshee 0.11.3, Inkscape 0.45, [] *Geom* - interactive geometry [] Any questions? Send me a PM, as I don't subscribe to every thread. Mark Shuttleworth... Last edited by gummibaerchen; January 5th, 2007 at 09:38 PM.. Reason: typo

January 7th, 2007	#4
gummibaerchen Gee! These Aren't Roasted! Join Date: Oct 2006 Beans: 152 Ubuntu 6.10 Edgy	Re: Hello Web - simplest web app in python Yeah, you're totally right. Maybe you should extend your 2 Examples with an interactive one, that may interested more people. For example http://example.com/cgi-bin/sqrt.py/81 And the output is Code: <h1>The Squareroot of 81 is 9</h1> __________________ Edgy Eft Packages: Glade-3 3.1.4, Geany 0.10, Banshee 0.11.3, Inkscape 0.45, [] *Geom* - interactive geometry [] Any questions? Send me a PM, as I don't subscribe to every thread. Mark Shuttleworth...

January 7th, 2007	#5
lazka 5 Cups of Ubuntu Join Date: Aug 2006 Location: Austria Beans: 44	Re: Hello Web - simplest web app in python http://webpython.codepoint.net/mod_p...er_hello_world

January 7th, 2007	#6
maddog39 Quad Shot of Ubuntu Join Date: Mar 2006 Location: Pennsylvania, US Beans: 452 Ubuntu 9.10 Karmic Koala	Re: Hello Web - simplest web app in python I finally got these two examples working, and here they are. http://www.dx-h.com/cgi-bin/cgitest.py - Example 1 http://www.dx-h.com/cgi-bin/cgitest2.py - Example 2 __________________ Ubuntu User #: 0x2695 \| Banshee 1.0 Pidgin Plugin Lenovo IdeaPad S10, 1.6GHz Intel Atom, Ubuntu 9.10 Netbook Remix

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