upload_example.py

from google.appengine.ext import blobstore
from google.appengine.ext import ndb

# Model for data.
class StoredFiles(ndb.Model):
    file_id = ndb.StringProperty()
    blob_key = ndb.BlobKeyProperty()

def get_upload_url():
    """Generates and returns an upload URL."""
    # Assume I want to upload a file with id "id". 
    file_id = "id" # for example
    u = URL('default', 'upload', args=[file_id])
    uu = blobstore.create_upload_url(u)
    return response.json(dict(upload_url=uu))
    

def upload():
    """Processes an upload to blobstore."""
    # We need to get the blob key from the upload.
    blob_info = blobstore.parse_blob_info(request.vars.content)
    if blob_info is not None:
        blob_key = blob_info.key()
        # We have our blob_key, now we need to store it somewhere, likely together with some other
        # parameters such as request.args(0) which corresponds to arg0 in controller/upload/arg0
        c = StoredFiles()
        c.file_id = request.args(0) or raise HTTP(500)
        c.blob_key = blob_key
        c.put()