root/branches/cherrypy-2.1/docs/book/xml/fileuploadbehavior.xml

<?xml version="1.0" encoding="UTF-8"?>
<section xmlns:db="http://docbook.org/docbook-ng"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
         xml:id="globaloverviewcherrypy">
    <title>File upload</title>
    <para>Before version 2.1, CherryPy handled file uploads by reading the
    entire file into memory, storing it in a string, and passing it to the
    page handler method. This worked well for small files, but not so well for
    large files.</para>
    <para>CherryPy 2.1 uses the python <code>cgi</code> module to parse the
    POST data. When a file is being uploaded, the <code>cgi</code> module
    stores it in a temp file and returns a <code>FieldStorage</code> instance
    which contains information about this file. CherryPy then passes this
    <code>FieldStorage</code> instance to the method. The
    <code>FieldStorage</code> instance has the following attributes:</para>
    <itemizedlist>
        <listitem><code>file</code>: the file(-like) object from which you can
        read the data</listitem>
        <listitem><code>filename</code>: the client-side filename</listitem>
        <listitem><code>type</code>: the content-type of the file</listitem>
    </itemizedlist>
</section>