Upload a photo to App Engine's Image service from a URL of an image elsewhere on the internet. Integrates App Engine's images service with InkPicker, so we can use their upload and store the actual image in our server

url_to_image_service.py

# Requires poster https://pypi.python.org/pypi/poster/
# Requires webapp2 on App Engine for demo

# Example usage:

# import requests
# 'http://upload.wikimedia.org/math/4/7/9/479d9d21b183eb546b771447fcf69ddf.png'
# response = requests.post('http://myapp.appspot.com/i/post_from_url', {'url': wikipediaimg})

import json
import urllib2

# Blobstore handlers for dealing with POST request
import webapp2
from google.appengine.api import urlfetch
from google.appengine.api import images
from google.appengine.ext import blobstore
from google.appengine.ext.webapp import blobstore_handlers


# Poster makes the multipart request easy
from poster.encode import multipart_encode, MultipartParam
from poster.streaminghttp import register_openers

# URLS are routed on this page for demonstration, not true in production
from webapp2 import Route, WSGIApplication
from imagehost_settings import app_config, IMAGE_UPLOAD_LOCATION

# App Engine doesn't allow writing to a file system, 
# which makes uploading photos a little trickier
# This code allows a post like this:
#{'url' : 'http://upload.wikimedia.org/math/4/7/9/479d9d21b183eb546b771447fcf69ddf.png'}
# to save the actual image in the images service

# Wherever your server expects to get multipart/form requests
IMAGE_UPLOAD_LOCATION = '/i/upload'


class PostFromURLHandler(webapp2.RequestHandler):
    def post(self):
        """ post an image url from somewhere else on the internet, get it posted to our own servers"""
        # get url of image we want to save on our servers
        image_url = self.request.get('url')
        upload_url = blobstore.create_upload_url(IMAGE_UPLOAD_LOCATION)
        # Need filetype and name for POST to work
        filetype = 'image/%s' % image_url.split('.')[-1]
        filename = image_url.split('/')[-1]
        raw_img = urlfetch.fetch(image_url).content
        multipart_param = MultipartParam('image', raw_img, filename=filename, filetype=filetype)
        datagen, headers = multipart_encode([multipart_param])
        
        # Post the image
        response = urlfetch.fetch(url=upload_url, payload="".join(datagen), method=urlfetch.POST, headers=headers)
        
        # Return whatever your image handlers normally return if uploading something
        # from a user's filesystem
        self.response.headers['Content-Type'] = 'application/json'
        self.response.out.write(response.content)



class ImageUploader(blobstore_handlers.BlobstoreUploadHandler):
    """ 
        Handles uploads for images, grabbing blob info from multipart handler and doing whatever
        with it (like saving its info to a model)
        /i/url leads to here
    """
    
    def post(self):

        attribute = self.request.get('attribute')
        fieldname = self.request.get('fieldname') or 'image'

        image_info = []
        #logging.info('looking at fieldname %s' % fieldname)
        for blobInfo in self.get_uploads():
            blobkey = blobInfo.key()
            # Get serving url for image
            image_url = images.get_serving_url(blobkey)
            
            # get image properties
            data = blobstore.fetch_data(blobkey, 0, 50000)
            actualImg = images.Image(image_data=data)
            #logging.info(actualImg)
            height = actualImg.height
            width = actualImg.width

            # Save your image somehow...
            
            # Add to array of successes
            image_info.append({'url': image_url,
                                'height': height,
                                'width': width,
                                })
        # Return its info
            
        self.response.headers['Content-Type'] = 'application/json'
        self.response.out.write(json.dumps(image_info))




rtes = [
        # image handlers
        Route(IMAGE_UPLOAD_LOCATION, handler='imagehost.api.ImageUploader'),
        Route(r'/i/post_from_url', handler='imagehost.api.PostFromURLHandler'),

]
application = WSGIApplication(rtes, config=app_config, debug=True)