How to use Google App Engine's Blobstore to save web images

Question

UPDATE

This question was originally asked at a time when there was no support for programmatic file creation (via url for example). That has changed, see: http://code.google.com/appengine/docs/java/blobstore/overview.html#Writing_Files_to_the_Blobstore

I'm accessing a couple different APIs to fetch images. My application is GAE + Python and I want to use the Blobstore to save these images. The GAE Blobstore documentation provides clear examples of how to save images to Blobstore via a form, but not directly from an url.

http://code.google.com/intl/iw/appengine/docs/python/blobstore/overview.html#Writing_Files_to_the_Blobstore

I want to know how to save http://api.website.com/images/foo.jpg to the Blobstore.

Answer 1

Using the new File API in combination with urlfetch API you should be able to pass the image url through the form, fetch it server-side and write it to the blobstore:

http://code.google.com/intl/iw/appengine/docs/python/blobstore/overview.html#Writing_Files_to_the_Blobstore

Answer 2

HTTP POST to your own form works. I didn't try submitting a file, but here's how I submit a form. You can get the file from the internet, add it to the form submission and the file will store in your blobstore.

import urllib
data = urllib.urlencode({"id":str(id), "password" : self.request.POST['passwd'], "edit" : "edit"})
result = urlfetch.fetch(url="http://www.montao.com.br/upload",
payload=data,
method=urlfetch.POST,
headers={'Content-Type': 'application/x-www-form-urlencoded'})

There's also a similar question answered here

I hope it works for you.

Answer 3

You could write an additional handler to upload the content of an input url to the blob store handler. i.e. automating the form submission process. make a POST request to the blob store handler and url encode the image.

But the only problem would be if the file is too large then you might get timeout exceptions.