[Web-SIG] transaction progress with cgi.FieldStorage

[Clark C. Evans]

On Thu, Dec 22, 2005 at 12:24:59PM -0500, kai wrote:
| this is my first post on this list. I am working on a way to monitor the 
| progress of reading a file upload from wsgi.input.  I can currently 
| monitor the overall transfer and when individual files of a multiple 
| file upload are completed. The ultimate goal of this is to be able to 
| display a progress meter when someone is uploading a file.

You could do this in a few stages:

  #1 Use an async XMLHttpRequest on the client side to POST
     the file to your file upload servlet; in the URL for the
     post use a unique identifier, say MY-ID

  #2 Override make_file /w your own that monitors how much
     of the file's content has been sent; store that in a 
     global mapping using MY-ID as the key

  #3 Create a monitor URL on your server that reads the mapping
     and returns an hour glass or something /w a refresh page

  #4 When you send your application request; open up an iframe
     /w refresh setting to that monitor URL (using MY-ID)

Although, you've probably already done something similar...

| To do this I subclassed cgi.FieldStorage but when I finished I had 
| modified most of the non-trivial methods just to hook in something to 
| monitor the transfer progress, oops.
| 
| Has anyone else found FieldStorage insufficient for certain tasks?
| Is there a general need for a more flexible FieldStorage replacement?

I've found make_file sufficient for all of my needs (so far)

Best,

Clark