def post(self):
dataUrlPattern = re.compile('data:image/(png|jpeg);base64,(.*)$')
file_data = self.request.get("file")
imgb64 = dataUrlPattern.match(file_data).group(2)
caption = self.request.get("caption")
upload = Upload()
upload.file = db.Blob(base64.b64decode(imgb64))
upload.caption = caption
upload.put()
self.redirect("/")
