How does Facebook share image base64 from Google App Engine

Question

Im working with Google App Engine Project and I want use facebook share like this.
https://i.stack.imgur.com/uz52n.png
Im already read this How does Facebook Sharer select Images and other metadata when sharing my URL?
but GAE cant upload physical Image, all image store in blob property in database as base64 so facebook share cant get the image :( anyone had another idea for this problem ??

Answer 1

Facebook reads the og:image meta to resolve the image from your webpage. og:image don't allow data-URI image (base64 encoded).

You have to provide an image url in og:image, but with that url, you can make a workaround to simulate the behaviour of a direct image resolution and get the image from your appengine database.

This is a solution in python using Django, but the concept works for everything. The name of the image is here "key.png" where key is the key of the object containing the base64 stored image.

First, add an url to the list of django urls for your image resolution:

(r'^image/(?P<key>[^\.^/]+)\.png$', 'yourapp.views.image'),

Then in your views, get the key from the url, retrieve your object, base64 decode and send it back with the correct mimetype:

import base64

def image(request, key):
    # get your object from database
    f = YourImageObject.get(key)

    # f.pic is the base64 encoded image
    pic = f.pic[len("data:image/png;base64,"):]    # remove the header

    # base64 decode and respond with correct mimetype
    return HttpResponse(base64.b64decode(pic), mimetype="image/png")