Getting AdWords customerId without a refresh token

Question

I'm working on a Web Application that allows user to connect AdWords account. 1) So once user connected their AW account I am getting token from AW API that includes an access token and a refresh token. So far so good, it's just a typical OAuth2 process.

2) Next time another user connects same AW account, AW would not provide me with a refresh token, assuming I have it stored somewhere, which is expected.

So here is the problem, there doesn't seem to be a way to get user information without the refresh token, meaning I can't identify the user to retrieve the refresh token.

I'm using .NET library (Google.Apis.Analytics.v3) and it doesn't allow me to request customer information without providing the refresh token...

Here is the sample code:

var tokenResponse = await adWordsService.ExchangeCodeForTokenAsync(code, redirectUri);
var adWordsUser = adWordsService.GetAdWordsUser();
var customerService = (CustomerService)adWordsUser.GetService(AdWordsService.v201502.CustomerService);
var customer = customerService.get();

adWordsService is just a wrapper around the API. so when I execute this line var customer = customerService.get() I get a following error:

ArgumentNullException: Value cannot be null.

Parameter name: AdWords API requires a developer token. If you don't have one, you can refer to the instructions at https://developers.google.com/adwords/api/docs/signingup to get one.

Google.Api.Ads.AdWords.Lib.AdWordsSoapClient.InitForCall(String methodName, Object[] parameters)

Developer token is there and so are all the client IDs.

If I add this line adWordsUser.Config.AuthToken = tokenResponse.AccessToken; before making the call, it complains about the refresh token.

ArgumentNullException: Value cannot be null.

Parameter name: Looks like your application is not configured to use OAuth2 properly. Required OAuth2 parameter RefreshToken is missing. You may run Common\Utils\OAuth2TokenGenerator.cs to generate a default OAuth2 configuration.

Google.Api.Ads.Common.Lib.OAuth2ProviderBase.ValidateOAuth2Parameter(String propertyName, String propertyValue)

So the question is, how does one acquire user information (in this case customerId, according to this article https://developers.google.com/adwords/api/docs/guides/optimizing-oauth2-requests#authenticating_multiple_accounts) during authentication for the purpose of storing the refresh token?

Answer 1

So I just found the problem is in the adWordsService. When the AdWordsUser is created it isn't assigned the updated authentication provider which contains the latest authentication token. Once this authentication provider is added the AdWordsUser doesn't try to refresh the token since the token hasn't expired yet, thus there is no need for the refresh token.