Directly Putting Data in AppEngine's Blobstore

Question

The AppEngine's standard API assumes files are uploaded from an HTML form. I'm trying to post a file to the blobstore from a REST API method that can be called by a non Html client (Flash, iPhone, etc.)

The code I'm trying to get working:

# Get the blobstore upload url    
upload_url = blobstore.create_upload_url("/activities/upload_finished");

# Make sync call to the blobstore url to post our image
result = urlfetch.fetch(url=upload_url,
                        payload=request.FILES,
                        method=urlfetch.POST,
                        headers={'Content-Type': 'multipart/form-data'})

I'm getting the following error:

ValueError: Invalid boundary in

Any idea?
Has anyone tried posting to the blobstore not through a web form?

multipart form: ''

Answer 1

App Engine (version 1.4.3) allows you to directly write data to the blobstore.
You no longer need to use the upload url method.

Answer 2

You can't make a regular post into a multipart form simply by specifying the content type - you're just submitting URL-encoded data with the wrong content type.

You'll need to assemble a proper multipart form - using the email module or by hand, like this.

Also see this question.