Service class using ruby/rails and google api client >.9. This uses google analytics service account.

google_analytics_service.rb

require 'google/apis/analytics_v3'

class GoogleAnalyticsService

  def initialize
    @filters = nil
    @metrics = "ga:uniquePageviews"
    @dimensions = 'ga:date'
  end

  # get string of key file in rails root
  # storing key in config path, feel free to change as needed.
  def google_api_key_path
    Rails.root.join('config', ENV['GA_API_KEY']).to_s
  end

  # return file for api key path
  def google_api_key
    File.open(google_api_key_path, "r")
  end

  # setup authorization given a specific scope
  def authorization(scope)
    Google::Auth::ServiceAccountCredentials.make_creds(json_key_io: google_api_key, scope: scope )
  end

  # primary service to gain scope and authorize analytics access
  def analytics_service
    scope = ['https://www.googleapis.com/auth/analytics.readonly']
    client = Google::Apis::AnalyticsV3::AnalyticsService.new
    client.authorization = authorization(scope)
    client
  end

  # the google analytics view id in api form
  # e.g. ga:XXXXXXXXX
  def ga_profile
    "ga:#{ENV['GA_VIEW_ID']}"
  end

  # A comma-separated list of dimension or metric filters to be applied to 
  # Analytics data.
  # e.g. 'ga:pagePath=~/featured/,ga:uniquePageviews>=20'
  # see https://github.com/tpitale/legato
  # https://developers.google.com/analytics/devguides/reporting/core/v3/reference#filters
  def change_filters(filters)
    @filters = filters
  end


  # A comma-separated list of Analytics metrics. E.g., 'ga:sessions,ga:pageviews'.
  # At least one metric must be specified.
  # e.g. 'ga:uniquePageviews'
  # https://developers.google.com/analytics/devguides/reporting/core/dimsmets
  def change_metrics(metrics)
    if metrics.present?
      @metrics = metrics
    end
  end

  # A comma-separated list of Analytics dimensions. E.g., 'ga:browser,ga:city'.
  # e.g. 'ga:date'
  # https://developers.google.com/analytics/devguides/reporting/core/dimsmets
  def change_dimensions(dimensions)
    @dimensions = dimensions
  end

  # Get the parameters to search the analytics api
  def analytics_analytics_parameters
    {
      'ids'         => ga_profile,
      'start-date'  => (Date.today - 30).strftime("%Y-%m-%d"),
      'end-date'    => Time.now.strftime("%Y-%m-%d"),
      'metrics'     => @metrics,
      'dimensions'  => @dimensions,
      'filters'     => @filters
    }
  end

  # request google analytics rows using ga_profile view
  # 30 days and any given metrics, dimensions and filters:
  # see https://ga-dev-tools.appspot.com/query-explorer/
  # 
  # uses api .get_ga_data as primary resource
  # see https://github.com/google/google-api-ruby-client/blob/master/generated/google/apis/analytics_v3/service.rb
  # @return analytics response
  #   .rows is the data
  def get
    analytics_service.get_ga_data(
      analytics_parameters['ids'],
      analytics_parameters['start-date'],
      analytics_parameters['end-date'],
      analytics_parameters['metrics'],
      dimensions: analytics_parameters['dimensions'],
      filters: analytics_parameters['filters']
    )
  end

end