I've soldiered through this over the last few weeks, so let me share what worked:
To use Oauth2 you need to get a 'refresh token' that you use to 're-authenticate' with google each time you make an API call. The steps for this are as follows:
1) Setup your account in the API console - https://code.google.com/apis/console/b/0/ (seems like you've done that well) 2) In your API account, make sure you have a redirect URI pointing back to your application:
http://some-url.com/auth/google_oauth2/callback
http://localhost:3000/auth/google_oauth2/callback
Note here that google won't let you call back to your local machine as 0.0.0.0:3000... so you'll need to use localhost explicitly
3) In your route file, tie that redirect url to an action in the controller where you're going to create the project or authentication
match '/auth/:provider/callback' => 'authentications#create'
The ':provider' simply lets you match on multiple types of oauth, but you could just put 'google_oauth2' there as well.
4) Now create that action in your controller
def create
auth = request.env["omniauth.auth"]
params = request.env["omniauth.params"]
project = Project.find(params['project_id'])
Authentication.create(:project_id => project.id, :provider => auth['provider'], :uid => auth['uid'], :access_token => auth['credentials']['refresh_token'])
flash[:notice] = "Authentication successful."
redirect_to owner_view_project_path(project)
end
5) The controller action should retrieve the relevant fields from the response object (details of response object here: https://github.com/zquestz/omniauth-google-oauth2) - in particular, you need to get the 'refresh_token' and save that to your project or authentication object - if you haven't added an 'access_token' attribute to the desired object, go do that now with a migration, then start saving the refresh token to that attribute
6) Now when you're ready to call that particular authentication and get API data for it, you can load up that object where you saved the access token, and use that to get a new session with the google API as follows:
@authentication = Authentications.find(params[:id])
client = OAuth2::Client.new GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET,
{
:site => 'https://accounts.google.com',
:authorize_url => "/o/oauth2/auth",
:token_url => "/o/oauth2/token",
}
response = OAuth2::AccessToken.from_hash(client, :refresh_token => @authentication.access_token).refresh!
Garb::Session.access_token = response
@profiles = Garb::Management::Profile.all
What this code did was create an OAuth2 access token (response) by specifying the client and then a refresh_token, then calling 'refresh!' to get a refreshed access token... then use that access token to establish your Garb session, then call down all the profiles for a given account using the Gard::Management::Profile.all
Hope this helps - let me know if you have questions!