Example of Google oAuth2Client login

google_login_oauth2client.py

# /start
def start_google(request):
	"""first step Oauth2 to google analytics and get code"""
	flow = OAuth2WebServerFlow(client_id = settings.GOOGLE_OAUTH2_CLIENT_ID,
						   client_secret = settings.GOOGLE_OAUTH2_CLIENT_SECRET,
						   scope = settings.GOOGLE_SCOPE,
						   redirect_uri = settings.OAUTH_REDIRECT_URI,
   						   access_type='offline',
						   )
	auth_uri = flow.step1_get_authorize_url()
	return HttpResponseRedirect(auth_uri) # This will then redirect back to /gconnect after the user accepted to share his/her data.

# /gconnect
def exchange_code_and_login(request):
	"""Step 2: connect to google analytics API"""
	flow = OAuth2WebServerFlow(client_id = settings.GOOGLE_OAUTH2_CLIENT_ID,
						   client_secret = settings.GOOGLE_OAUTH2_CLIENT_SECRET,
						   scope = settings.GOOGLE_SCOPE,
						   redirect_uri = settings.OAUTH_REDIRECT_URI,
						   access_type='offline', # Does it work? How can I test it?
						)

	if request.method == 'GET':
		if 'code' in request.GET:
			code = request.GET['code']
			credentials = flow.step2_exchange(code)
			http = httplib2.Http()
			http = credentials.authorize(http)
			v3_service = build('analytics', 'v3', http=http)
			google_profile = v3_service.management().accountSummaries().list().execute()
			google_email = google_profile['username']
			# Check if user exists
			try:
				current_user = User.objects.get(username=google_email)
			except User.DoesNotExist:
				current_user = User.objects.create_user(username=google_email)
			current_user.backend = 'django.contrib.auth.backends.ModelBackend'
			# Save Google Profile to DB
			obj, created = GoogleProfile.objects.get_or_create(user_id=current_user.id, defaults={'google_profile': google_profile,'google_email': current_user,})
			if not created: # If the user exists, these things will be replaced:
				obj.google_profile = google_profile
				obj.google_email = google_email
				obj.save()
			# Save Credentials to DB
			obj, created = CredentialsModel.objects.get_or_create(user_id=current_user.id, defaults={'credentials': credentials, 'google_email': google_email})
			if not created:  # If the user exists, these things will be replaced:
				obj.credentials = credentials
				obj.google_email = google_email
				obj.save()
			# Login User
			if current_user:
				login(request, current_user)
			else:
				print('problem logging in user')
				current_user = None
			return user_settings(request) # Or any view, the user is now logged in and credentials are save in the DB
		else:
			return HttpResponse('Sorry, code not in request. <br> <br> Click <a href="/start"> here</a> to try again')