PDF App Engine转换

Question

这是我第二次尝试获得帮助。 我只是试图在PNG中转换PDF附件，但没有成功。

这是我的代码：

class FAX(db.Expando):
    date = db.DateTimeProperty(auto_now_add=True)

class LogSenderHandler(InboundMailHandler):
    def receive(self, mail_message):
        for elemento in mail_message.attachments:
            asset = conversion.Asset("application/pdf", str(elemento[1]), "Fax.pdf")
            conversion_obj = conversion.Conversion(asset, "image/png")
            result = conversion.convert(conversion_obj)
            for elemento2 in result.assets:
                fax = FAX()
                fax.immagine = elemento2.data
                fax.put()

def main():
    application = webapp.WSGIApplication([LogSenderHandler.mapping()], debug=True)
    wsgiref.handlers.CGIHandler().run(application)

if __name__ == '__main__':
        main()

这是日志：

0.1.0.20 - - [05/Apr/2012:02:04:33 -0700] "POST /_ah/mail/fax@faxmeraviglie.appspotmail.com HTTP/1.1" 200 124 - - "faxmeraviglie.appspot.com" ms=558 cpu_ms=163 api_cpu_ms=0 cpm_usd=0.010690 loading_request=1 instance=00c61b117c45eeb741ec2540095a8ba3862842