Google API: getting Credentials from refresh token with oauth2client.client

I am using googles official oauth2client.client to access the google plus api. I have a refresh token (that does not expire) stored in a database, and need to recreate the temporary "Credentials" (access token) from that.

But I could not find a way to do this with to official library supplied by google.

So I hacked around it: used urllib to access the API that gives me a new access_token from the refresh_token. Using the access_token I can then use the library.

I must be missing somthing!

from apiclient import discovery
from oauth2client.client import AccessTokenCredentials
from urllib import urlencode
from urllib2 import Request , urlopen, HTTPError
import json

# ==========================================

def access_token_from_refresh_token(client_id, client_secret, refresh_token):
  request = Request('https://accounts.google.com/o/oauth2/token',
    data=urlencode({
      'grant_type':    'refresh_token',
      'client_id':     client_id,
      'client_secret': client_secret,
      'refresh_token': refresh_token
    }),
    headers={
      'Content-Type': 'application/x-www-form-urlencoded',
      'Accept': 'application/json'
    }
  )
  response = json.load(urlopen(request))
  return response['access_token']

# ==========================================

access_token = access_token_from_refresh_token(CLIENT_ID, CLIENT_SECRET, REFRESH_TOKEN)

# now I can use the library properly
credentials = AccessTokenCredentials(access_token, "MyAgent/1.0", None)
http = credentials.authorize(httplib2.Http())
service = discovery.build('plus', 'v1', http=http)
google_request = service.people().get(userId='me')
result = google_request.execute(http=http)

I use: oauth2client.client.GoogleCredentials

    cred = oauth2client.client.GoogleCredentials(access_token,client_id,client_secret,
                                          refresh_token,expires_at,"https://accounts.google.com/o/oauth2/token",some_user_agent)
    http = cred.authorize(httplib2.Http())
    cred.refresh(http)
    self.gmail_service = discovery.build('gmail', 'v1', credentials=cred)

You can construct an OAuth2Credentials instance directly like this:

import httplib2
from oauth2client import GOOGLE_REVOKE_URI, GOOGLE_TOKEN_URI, client

CLIENT_ID = '<client_id>'
CLIENT_SECRET = '<client_secret>'
REFRESH_TOKEN = '<refresh_token>'

credentials = client.OAuth2Credentials(
    access_token=None,  # set access_token to None since we use a refresh token
    client_id=CLIENT_ID,
    client_secret=CLIENT_SECRET,
    refresh_token=REFRESH_TOKEN,
    token_expiry=None,
    token_uri=GOOGLE_TOKEN_URI,
    user_agent=None,
    revoke_uri=GOOGLE_REVOKE_URI)

credentials.refresh(httplib2.Http())  # refresh the access token (optional)
print(credentials.to_json())
http = credentials.authorize(httplib2.Http())  # apply the credentials

I solved this quite easily (you certainly miss this documentation). This is a snippet of my code that tries to use Picasa API to get all of album from active user:

    http = httplib2.Http(ca_certs=os.environ['REQUESTS_CA_BUNDLE'])
    try:
        http = self.oauth.credentials.authorize(http)
        response, album_list = http.request(Picasa.PHOTOS_URL, 'GET')
        if response['status'] == '403':
            self.oauth.credentials.refresh(http)
            response, album_list = http.request(Picasa.PHOTOS_URL, 'GET')
        album_list = json.load(StringIO(album_list))
    except Exception as ex:
        Logger.debug('Picasa: error %s' % ex)
        return {}

Use the refresh method coming from oauth2client.client.OAuth2Credentials. I think it's even okay to use if response['status'] != '200'. Got to check that!

Google API: getting Credentials from refresh token with oauth2client.client

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