Using Google Analytics Reporting API v4 in Rails with Oauth2

analyticsreportingv4.rb

# This summary shows how to set up a basic request to Google's Analytics Reporting API v4 from a Rails app.

# Gemfile
gem 'google-api-client', # v. 0.11
gem 'omniauth-google-oauth2' # v. 0.4.1 with Devise

# In a model or controller somewhere...
analytics = Google::Apis::AnalyticsreportingV4::AnalyticsReportingService.new
analytics.authorization = current_user.token # See: https://github.com/zquestz/omniauth-google-oauth2

date_range = Google::Apis::AnalyticsreportingV4::DateRange.new(start_date: '7DaysAgo', end_date: 'today')
metric = Google::Apis::AnalyticsreportingV4::Metric.new(expression: 'ga:sessions', alias: 'sessions')
dimension = Google::Apis::AnalyticsreportingV4::Dimension.new(name: 'ga:browser')

request = Google::Apis::AnalyticsreportingV4::GetReportsRequest.new(
  report_requests: [Google::Apis::AnalyticsreportingV4::ReportRequest.new(
    view_id: 'VIEW_ID_FROM_ANALYTICS_PROPERTY',
     metrics: [metric],
     dimensions: [dimension],
     date_ranges: [date_range]
  )]
) # thanks to @9mm: https://github.com/google/google-api-ruby-client/issues/489

response = analytics.batch_get_reports(request)
response.reports

Hi, sir
I'm unable to authorize the reporting API because I have a rake task that everyday runs and collects data but in the rake, task authorization is required without a consent screen and I have not added omniauth gem but with google-api-client gem I have to make request to reporting API. why does authorization fail?