Twitter media/upload image by its web url - python-2.7

Question

I followed the steps in media/upload. I wrote this function in python
def upload_media(self,access_token,image_url):
client = self.get_client(access_token)
message = {'media' : image_url}
encoded_status = urllib.urlencode(message)
url = "https://upload.twitter.com/1.1/media/upload.json?"+ encoded_status
resp, content = client.request(url,'post')
return content
And I got this :
{"request":"\/1.1\/media\/upload.json","error":"media type unrecognized."}

Answer 1

As far as I can tell, the error is in trying to upload a URL. The Twitter API requires you to upload a base64-encoded image.
See: https://dev.twitter.com/rest/reference/post/media/upload
So instead of the image's URL, it should be the file content:
with open('example.jpg', 'rb') as f:
data = f.read()
message = {'media':data}
Optionally (I still haven't figured out whether this is required or not, as different people give different answers), you could encode the image in base-64 encoding:
with open('example.jpg', 'rb') as f:
data = f.read()
data = data.encode('base64')
message = {'media':data}