Feature Request: Add Option to Cache Access Token

Hi,

I’m trying to get a basic example working, but keep receiving the same error:

...
    return _end_unary_response_blocking(state, call, True, None)
  File "/Users/Louis/anaconda3/lib/python3.6/site-packages/grpc/_channel.py", line 466, in _end_unary_response_blocking
    raise _Rendezvous(state, None, None, deadline)
grpc._channel._Rendezvous: <_Rendezvous of RPC that terminated with:
	status = StatusCode.UNAUTHENTICATED
	details = "Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project."
	debug_error_string = "{"created":"@1537546478.122567000","description":"Error received from peer","file":"src/core/lib/surface/call.cc","file_line":1099,"grpc_message":"Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.","grpc_status":16}"

The example code is shown below:

import google.ads.google_ads.client

customer_id = "123"
client = google.ads.google_ads.client.GoogleAdsClient.load_from_storage(
    "google-ads.yaml")
ga_service = client.get_service("GoogleAdsService")

query = ('SELECT campaign.id FROM campaign ORDER BY campaign.id')
results = ga_service.search(customer_id, query)

try:
    for row in results:
        print('Campaign with ID %d and name "%s" was found.'
              % (row.campaign.id.value, row.campaign.name.value))
except google.ads.google_ads.errors.GoogleAdsException as ex:
    print('Request with ID "%s" failed with status "%s" and includes the '
          'following errors:' % (ex.request_id, ex.error.code().name))

My credentials file google-ads.yaml is set up as follows:

client_id: CLIENT_ID
client_secret: CLIENT_SECRET
refresh_token: REFRESH_TOKEN
developer_token: DEVELOPER_TOKEN 

I assume the GoogleAdsClient generates an access_token from the refresh_token? Am I misunderstanding how to send an authenticated request?

Thanks,

Louis

[kritzware]

It could be useful for when performing many operations/reporting queries with many different clients (i.e. different customer ids), thus meaning it doesn’t have to refresh the access token for these client instances every time if it’s before the cached token expiry date 👍

[wihl]

This issue is on hold pending a decision to make this functionality available for all supported client libraries.