AJAX Uploader with Nginx, Not Catching Files

Has anyone set up nginx to work with an AJAX uploader like this one
before? http://valums.com/ajax-upload/

Passing the upload through to my Tornado server works fine, but I want
nginx to handle the file before it gets that far. I have nginx set up
to intercept regular file posts from our pre-AJAX page with
“upload_pass” and “upload_store,” but now with the file in the body of
an XHR request, nginx doesn’t treat it as a file for things like

Also, my AJAX page gets back a 415 error when trying to send the file.
I’m using the script for image uploads if that makes a difference.

I was thinking I might be able to save a log of the request as the image
file, but that seems like too much of a hack.

Any help appreciated,

Posted at Nginx Forum: