GAE + Cloud Storage - Unable to get FileInfo after File is uploaded - google-app-engine

Question

I am using Flask Web Framework on GAE/Python. After uploading a file to Cloud Storage I want to get a reference to the file so that it can be served. I can't get the parse_file_info to work. I've searched long and hard and spent over two days trying to make this work. I'm at my wit's end!! You can see my handlers below:
#app.route('/upload_form', methods = ['GET'])
def upload_form():
blobupload_url = blobstore.create_upload_url('/upload', gs_bucket_name = 'mystorage')
return render_template('upload_form.html', blobupload_url = blobupload_url)
#app.route('/upload', methods = ['POST'])
def blobupload():
file_info = blobstore.parse_file_info(cgi.FieldStorage()['file'])
return file_info.gs_object_name

Answer 1

The data is encoded in the payload of uploaded_file you retrieve after uploading a blob. This is example code on how to extract the name:
import email
from google.appengine.api.blobstore import blobstore
def extract_cloud_storage_meta_data(file_storage):
""" Exctract the cloud storage meta data from a file. """
uploaded_headers = _format_email_headers(file_storage.read())
storage_object_url = uploaded_headers.get(blobstore.CLOUD_STORAGE_OBJECT_HEADER, None)
return tuple(_split_storage_url(storage_object_url))
def _format_email_headers(raw_headers):
""" Returns an email message containing the headers from the raw_headers. """
message = email.message.Message()
message.set_payload(raw_headers)
payload = message.get_payload(decode=True)
return email.message_from_string(payload)
def _split_storage_url(storage_object_url):
""" Returns a list containing the bucket id and the object id. """
return storage_object_url.split("/")[2:4]
#app.route('/upload', methods = ['POST'])
def blobupload():
uploaded_file = request.files['file']
storage_meta_data = extract_cloud_storage_meta_data(uploaded_file)
bucket_name, object_name = storage_meta_data
return object_name