Accessing authenticated Google Cloud Endpoints API from Google Apps Script - google-app-engine

Question

I'm trying to pull some data into a Google sheets spreadsheet from an API that's been built using Google Cloud Endpoints. Here is the API declaration:
#Api(
name = "myendpoint",
namespace =
#ApiNamespace
(
ownerDomain = "mydomain.com",
ownerName = "mydomain.com",
packagePath = "myapp.model"
),
scopes = {SCOPES},
clientIds = {ANDROID_CLIENT_ID, WEB_CLIENT_ID, API_EXPLORER_CLIENT_ID},
audiences = {WEB CLIENT_ID}
)
The method I'm trying to access has authentication enabled by means of the user parameter in the API declaration:
#ApiMethod(name = "ping", httpMethod = HttpMethod.GET, path = "ping")
public StringResponse getPing(User user) throws OAuthRequestException {
CheckPermissions(user);//throws an exception if the user is null or doesn't have the correct permissions
return new StringResponse("pong");
}
This works fine when using the generated client libraries or the gapi js library. However AFAIK I can't use those js libraries in Apps Script.
I've got an OAuth2 flow working using the apps-script-oauth2 library from here, and I'm pretty much using the default setup for creating the service
function getService() {
// Create a new service with the given name. The name will be used when
// persisting the authorized token, so ensure it is unique within the
// scope of the property store.
return OAuth2.createService(SERVICE_NAME)
// Set the endpoint URLs, which are the same for all Google services.
.setAuthorizationBaseUrl('https://accounts.google.com/o/oauth2/auth')
.setTokenUrl('https://accounts.google.com/o/oauth2/token')
// Set the client ID and secret, from the Google Developers Console.
.setClientId(CLIENT_ID)
.setClientSecret(CLIENT_SECRET)
// Set the name of the callback function in the script referenced
// above that should be invoked to complete the OAuth flow.
.setCallbackFunction('ruggedAuthCallback')
// Set the property store where authorized tokens should be persisted.
.setPropertyStore(PropertiesService.getUserProperties())
// Set the scopes to request (space-separated for Google services).
.setScope(SCOPES)
// Below are Google-specific OAuth2 parameters.
// Sets the login hint, which will prevent the account chooser screen
// from being shown to users logged in with multiple accounts.
.setParam('login_hint', Session.getActiveUser().getEmail())
// Requests offline access.
.setParam('access_type', 'offline')
// Forces the approval prompt every time. This is useful for testing,
// but not desirable in a production application.
.setParam('approval_prompt', 'auto')
//.setParam('include_granted_scopes', 'true');
}
These are my methods for accessing the APIs
function getDriveDocs() {
return executeApiMethod('https://www.googleapis.com/drive/v2/','files?maxResults=10');
}
function pingServer(){
return executeApiMethod('https://myapp.appspot.com/_ah/api/myendpoint/v1/','ping');
}
function executeApiMethod(apiUrl, method)
{
//var url = ;
var url = apiUrl + method;
var service = getRuggedService();
return UrlFetchApp.fetch(url, {
'muteHttpExceptions': true,
'method': 'get',
'headers': {
Authorization: 'Bearer ' + service.getAccessToken()
}
});
}
The getDriveDocs() method works perfectly, so I know my auth flow is working correctly. Also, if I call an unauthenticated method in my API I get the correct response. However, when I call the authenticated 'ping' method, the 'user' parameter is always null. Am I missing something in the fetch call? Everything I've read so far seems to suggest that setting
Authorization: 'Bearer ' + service.getAccessToken()
should be enough.
Any help would be much appreciated!

Answer 1

This turned out to be a simple mistake - I had created a new oauth2 credential in the google dev console and had not added the new client id to the API declaration. Here is the working API declaration:
#Api(
name = "myendpoint",
namespace =
#ApiNamespace
(
ownerDomain = "mydomain.com",
ownerName = "mydomain.com",
packagePath = "myapp.model"
),
scopes = {SCOPES},
clientIds = {ANDROID_CLIENT_ID, WEB_CLIENT_ID, API_EXPLORER_CLIENT_ID, GAPPS_CLIENT_ID},
audiences = {WEB CLIENT_ID}
)