[mod_python] Transparently using mod_python to handle images

Rich McDonough wrote ..
> First let me extend my thanks to this group. It is a fountain of useful
> information.
> 
> I am sure that this question will be easily answered by someone here, in
> fact there is probably some code snippets around that will do the deed
> quickly and easily. I am trying to write a handler that will server 
> images from a subdirectory. The goal is to have the handler serve the 
> image and insert a record into a database indicating the referring page,
> filename, time, etc... It would ideally be a folder within a UserDir, so
> for this to work the user would have to add the appropriate .htaccess 
> and index.py files added to it. Users would then just add the images 
> they want served to the folder, the handler would do the rest.
> 
> I have been doing this with Zope for a while now but need to move away
> from zodb due to size issues. Also, my current approach requires the URL
> to be rather ugly and include an argument (i.e. 
> http://server/folder/image?sparky.jpg). I would love to get away from 
> passing the argument in the URL and simply have users place the real 
> path to the image, then let the handler do the manipulating for me.
> 
> Does anyone have any quick pointers or examples of such an application?

I would not recommend using mod_python.publisher for this, use a
basic content handler instead and you don't have to use form paramaters.
It is actually quite easy, just put the following code in the images
directory as "_images.py".

  from mod_python import apache

  import os

  def handler(req):

    if req.filename == __file__:
      return apache.HTTP_FORBIDDEN
    elif req.filename == __file__ + 'c':
      return apache.HTTP_FORBIDDEN

    if os.path.exists(req.filename):
      apache.log_error("fetch "+req.filename)

    return apache.DECLINED

Modify the log line to what you need as appropriate.

In the .htaccess file for that directory then have:

  SetHandler python-program
  PythonHandler _images

If you then access:

  /images/foo.gif

It will log the access and then by returning apache.DECLINED
pushes the request back to Apache which will then send back
the content of the actual file.

Graham