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Oct 01

HOWTO: apache2 & mod_python

Tags:apache2, embeded, howto, import, mod-python, mod-python.psp, mod-python.publisher, module — Ignace Mouzannar (ghantoos) @ 1:31 pm

Here are two mod_python howtos I wrote, hope they are helpful in any way:
1. Publisher handler : mod_python.publisher
2. PSP handler : mod_python.psp

Part 1: mod_pythton.publisher section:

After a bit of research and some debugging time, and as i couldn’t find obvious mod_python howtos, I decided to write a little Apache2/mod_python howto.

The first thing to do, of course, is to setup your web server to handle python code.
To do so, you must edit your site’s apache2 configuration file. In this example, we will edit the “default” site of apache2.
As root, add the following to your configuration file:

vi /etc/apache2/sites-available/default

and add:

 ServerAdmin webmaster@localhost
 DocumentRoot /path/to/your/sites/files
 AddHandler mod_python .py
 PythonHandler mod_python.publisher
 PythonDebug On
 ...

When this is done, you must restart apache2 to reload your new configuration. (sudo /etx/init.d/apache2 restart)

Hello world!

The first thing to do to test your configuration, is to create a “hello wolrd!” page : )
Go to your site’s file path (by default /var/www/), create a file named hello.py and paste in it the following:

def index():

	return "Hello world!"

Now try it: http://server_ip/hello.py
This should just give you a text output embedded in to the page. No HTML source code is present.
WARNING:
As you can test, when loading a python based page, the method that is looked for by default is “index()”.
So, if your try changing the name of the index definition into bloup, this shouldn’t work!

The requested URL /hello.py was not found on this server.

We’ll see how to get over this in part 3.

First HTML:

Now let’s write our first HTML page. This page will ,of course, have dynamic content, else, you should just code in HTML without bothering to do it through mod_python. : )
What we’ll do is import some standard python modules, and use some of their output in our page. For instance, the time and date of the server. For that we will import the time module:

import time

def index():

	html = """
<html><head>
<title>mod_python.publisher first html page</title>
</head>
<body>
<h1>This page was generated by mod_python.publisher</h1><hr>
The local time of this server is:  %sThe timezone of this server is  :  %s
</body>
</html>
""" % (time.ctime(time.time()), time.timezone/3600)

	return html

This should return something like:
This page was generated by mod_python.publisher

The local time of this server is: Fri Sep 28 16:27:38 2007
The timezone of this server is : -1 GMT

Create a function (other than index() ) and call it:

In the last parts we only called the .py file through our browser, which will call the index() function by default.
To get the output of a other function, get_time() for example, you must enter: http://server_ip/hello.py/get_time

import time

def index():	

	return "index().. nothing here.."

def get_time():

	html = """
<html><head>
<title>get_time function</title>
</head>
<body>
<h1>get_time function</h1>
<hr>
The local time of this server is:  %s <br>
The timezone of this server is  :  %s <br>
</body>
</html>""" % (time.ctime(time.time()), time.timezone/3600)

	return html

HTML POST method with mod_python:

Let’s see how to post some info through a “submit” button, and use it in mod_python function.
First of all, lets create a simple html post:

def index():	

	return """
<html><head>
<title>get_time function</title>
</head>
<body>
<FORM value="form" action="hello.py/get_info" method="post">
  <P>
	<LABEL for="firstname">First name: </LABEL>
	<INPUT type="text" name="firstname"><BR>
	<LABEL for="lastname">Last name: </LABEL>
	<INPUT type="text" name="lastname"><BR>
	<LABEL for="email">email: </LABEL>
	<INPUT type="text" name="email"><BR>
	<INPUT type="radio" name="gender" value="Male"> Male<BR>
	<INPUT type="radio" name="gender" value="Female"> Female<BR>
	<INPUT type="submit" value="Send"> <INPUT type="reset">
  </P>
</FORM>
</body>
</html>
"""

Now let’s create the get_info method to gather the info posted from the form:

def get_info(req): 

	info = req.form	

	a = info['firstname']
	b = info['lastname']
	c = info['email']
	d = info['gender']

	return """
<html><head>
<title>POST method with mod_python</title>
</head>
<body>
<h1>POST method with mod_python</h1>
<hr><br>
Your firstname is: %s <br>
Your lastname is: %s <br>
Your email is: %s <br>
You are a %s <br>
</body>
</html>
""" %(a,b.upper(),c,d.lower())

To test it, goto http://server_ip/hello.py, enter the required information in the form and submit.
This should generate a html output with the info you have just entered.

Import a customized module in your mod_python code (from my last post):

In this example, we will try to import the module bloup.py located in the same directory of my index.py mainpage.
when trying to import using the usual means, we get:

#!/usr/bin/env python
import os
import bloup
...

>>>ImportError: No module named bloup

The solution I found was:

import os

from mod_python import apache

directory = os.path.dirname(__file__)
bloup = apache.import_module('bloup', path=[directory])

You can checkout my source: http://www.dscpl.com.au/wiki/ModPython/Articles/BasicsOfModuleImporting

One last thing..

Now one last thing: posting variables through the address bar.
Let’s say we have a simple “bloup” variable in the index method: index(bloup)
You would just have to call the script this way: http://server_ip/hello.py?bloup=”Hello World!”

def index(bloup=""):

	return """<html><head>
<title>get_time function</title>
</head>
<body>
<h1> %s </h1>
</body>
</html>
""" % bloup

Conclusion:

I hope this was helpful. If you have any comment or tips, post it!
I’ll be glad to help or be helped..: )
Cheers,

Ghantoos

Part 2: mod_pythton.psp section:

Here is a second howto about the PSP handler of mod_python.

Hope this is useful!

The PSP handler of mod_python is what you need to use to have python code embeded in your page (more or less like with php).

vi /etc/apache2/sites-available/default

and add:

 ServerAdmin webmaster@localhost
 DocumentRoot /path/to/your/sites/files
 AddHandler mod_python .py
 PythonHandler mod_python.psp
 PythonDebug On
 ...

When this is done, you must restart apache2 to reload your new configuration. (sudo /etx/init.d/apache2 restart)

Hello world!

<%= 'Hello World!' %>

Now try it: http://server_ip/hello.psp
This should just give you a text output embedded in to the page. No HTML source code is present.
WARNING:
As you can test, when loading a python based page, the method that is looked for by default is “index()”.
So, if your try changing the name of the index definition into bloup, this shouldn’t work!

The requested URL /hello.py was not found on this server.

We’ll see how to get over this in part 3.

First HTML:

<html><head>
<title>mod_python.psp first html page</title>
</head>
<body>
<% import time %>
<h1>This page was generated by mod_python.psp</h1><hr>

The local time of this server is:  <%= time.ctime(time.time()) %>
The timezone of this server is  :  <%= time.timezone/3600 %>

</body>
</html>

This should return something like:
This page was generated by mod_python.psp

The local time of this server is: Fri Sep 28 16:27:38 2007
The timezone of this server is : -1 GMT

HTML POST method with mod_python:

Let’s see how to post some info through a “submit” button, and use it in mod_python function.
First of all, lets create a simple html post:

<html><head>
<title>mod_python.psp Forms</title>
</head>
<body>
<%
if form.has_key('firstname'):
	req.write("<pre>")
	req.write("Your firstname is: " + form['firstname'] + "<br>")
	req.write("Your lastname is: " + form['lastname'].upper() + "<br>")
	req.write("Your email is: " + form['email'] + "<br>")
	req.write("You are a " + form['gender'] + "<br>")
	req.write("</pre>")
else:
%>
<FORM value="form" action="hello.psp" method="post">
  <P>
	<LABEL for="firstname">First name: </LABEL>
	<INPUT type="text" name="firstname"><BR>
	<LABEL for="lastname">Last name: </LABEL>
	<INPUT type="text" name="lastname"><BR>
	<LABEL for="email">email: </LABEL>
	<INPUT type="text" name="email"><BR>
	<INPUT type="radio" name="gender" value="Male"> Male<BR>
	<INPUT type="radio" name="gender" value="Female"> Female<BR>
	<INPUT type="submit" value="Send"> <INPUT type="reset">
  </P>
</FORM>

</body>
</html>

To test it, goto http://server_ip/hello.psp, enter the required information in the form and submit.
This should generate a html output with the info you have just entered.

Import a customized module in your mod_python code (from my last post):

In this example, we will try to import the module EXIF.py located in the same directory of my index.py mainpage.
when trying to import using the usual means, we get:

<%
import os
import EXIF
...
%>
>>>ImportError: No module named bloup

The solution I found was:

import os

from mod_python import apache

bloup = apache.import_module('bloup', path=['/path/to/py_module/file/'])

You can checkout my source (for mod_python.publisher): http://www.dscpl.com.au/wiki/ModPython/Articles/BasicsOfModuleImporting

Conclusion:

I didn’t find how to post a variable through the address bar..

I feel like the psp handler of mod_python is nicer to read, the publisher has a charm I like.

Again, I hope this was helpful. And again, if you have any comment or tips, post it!
I’ll be glad to help or be helped..: )
Cheers,

Ghantoos

Comments (11)

11 Responses to “HOWTO: apache2 & mod_python”

Place Ghantoos » HOWTO: apache2 & mod_python says:
October 1st, 2007 at 1:36 pm

[...] HOWTO: apache2 & mod_python [...]
haden says:
January 8th, 2009 at 9:52 am

Great post… really helped me out.. was stuck with mod_python.publisher.. now my problem is solved
Bruce says:
March 26th, 2009 at 3:01 pm

Cheers for the examples, they helped clear a few things up for me.

Once thing I can’t workout and have not been able to find any working examples is “form based user authentication” using sessions. I’m able to implement sessions and query postgres etc……but I can’t find a “this is how you do it in python” example of user auth using sessions.

Any ideas?

Thanks again!!!!!
wwli says:
April 6th, 2009 at 9:11 pm

Thanks for the great post! I have been searched around, this one is very clear and useful!!
korvin says:
May 4th, 2009 at 8:26 am

Thanks!!! It’s only place where I found working solution!!!
Adil says:
May 22nd, 2009 at 12:42 pm

Thanks for the great post.
Now i’m asking if it is possible to embed both .psp and .py files at the same time within apache?
I tried to add instructions of .psp & .py in httpd.con file but it does not work :( .
Ignace Mouzannar (-ghantoos-) says:
May 22nd, 2009 at 2:05 pm

@Bruce
Sorry I can’t help you with that.

@Adil
I’m not sure you can actually do this.
It could be done on 2 different virtual hosts, but you cannot specify 2 different values of PythonHandler for one vhost.

Other than this, I’m glad this post helped! :)

Cheers,
Ignace M -ghantoos-
Graham Dumpleton says:
May 30th, 2009 at 6:31 am

See also:

http://webpython.codepoint.net/mod_python_tutorial
assem says:
September 5th, 2009 at 4:41 pm

thank you ,
Herald says:
December 18th, 2009 at 11:31 am

Great post, thanks!!
Dave says:
December 24th, 2009 at 2:26 pm

Thanks for the info!

HOWTO: apache2 & mod_python

Part 1: mod_pythton.publisher section:

Hello world!

First HTML:

Create a function (other than index() ) and call it:

HTML POST method with mod_python:

Import a customized module in your mod_python code (from my last post):

One last thing..

Conclusion:

Part 2: mod_pythton.psp section:

Hello world!

First HTML:

HTML POST method with mod_python:

Import a customized module in your mod_python code (from my last post):

Conclusion:

11 Responses to “HOWTO: apache2 & mod_python”

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