sample code for setting up the Google Prediction API in a background process using OAuth2 and the google-api-ruby-client

20110629202502_create_oauth2s.rb

class CreateOauth2s < ActiveRecord::Migration
  def self.up
    create_table :oauth2s do |t|
      t.string :api
      t.string :refresh_token
      t.string :access_token
      t.datetime :expires_at

      t.timestamps
    end
    add_index :oauth2s, :api
  end

  def self.down
    drop_table :oauth2s
  end
end

google_prediction.rb

require 'gstore'
require 'fastercsv'
require 'google/api_client'

class GooglePrediction
  include ActionView::Helpers::NumberHelper

  @message_fields = [:spam_or_ham, :message, :ips, :email, :rating, ... ]
  @training_set = []
  @test_set = []
  BUCKET = 'messages'
  API = 'google-prediction'

  def self.client
    if @client.nil?
      @client = Google::APIClient.new
      @client.authorization.client_id = "MY_CLIENT_ID"
      @client.authorization.client_secret = "MY_CLIENT_SECRET"
      @client.authorization.scope = 'https://www.googleapis.com/auth/prediction'
      @client.authorization.redirect_uri = "urn:ietf:wg:oauth:2.0:oob"
      
      # authenticate!
      if oauth2 = Oauth2.find_by_api(API) and oauth2.access_token.present?
        @client.authorization.update_token!(oauth2.token_hash)
        if oauth2.expired?
          puts "REFRESHING ACCESS TOKEN"
          @client.authorization.redirect_uri = nil
          @client.authorization.fetch_access_token!
          oauth2.update_token! @client.authorization
        end
      end
    end
    @client
  end
  
  def self.setup code=nil
    oauth2 = Oauth2.find_by_api(API)
    if oauth2.nil?
      oauth2 = Oauth2.create!(:api => API)
    end
    
    if code.nil?
      puts "Authorize the API in the browser at: \n\n#{client.authorization.authorization_uri.to_s}\n\n"
      puts 'Then call again with script/runner "GooglePrediction.setup \'CODE\'"' 
      return
    else
      client.authorization.code = code
      client.authorization.fetch_access_token!
      oauth2.update_token! client.authorization
      puts "You are now authenticated!"
    end
  end

  def self.run
    # generate CSV to upload
    csv_string = FasterCSV.generate do |csv|
      Message.find_each(:include => :user) do |message|
        next if message.user.nil?
        if rand > 0.5
          @training_set << post.id
        else
          @test_set << post.id
          csv << @message_fields.collect {|f| post.send(f)}
        end
      end
    end
    filename = store_in_google(csv_string)
    
    prediction = client.discovered_api('prediction', 'v1.2')
    
    puts "Training..."
    response = client.execute(prediction.training.insert,{'data' => "#{BUCKET}/#{filename}"})
    while true
      sleep 4
      response = client.execute(prediction.training.get, {'data' => "#{BUCKET}/#{filename}"})
      response = JSON.parse(response[2][0])
      if response['trainingStatus'] == "DONE"
        puts response
        break
      end
    end
    
    # training done!
    
  ensure
    delete_from_google filename
  end
  
  def self.gstore_client
    @gstore_client ||= GStore::Client.new(
    :access_key => "My Google Storage Legacy Access Key",
    :secret_key => "My Google Storage Legacy Secret Key"
    )
  end

  def self.store_in_google data
    puts "Uploading #{data.length / 1000 / 1000}MB to google storage..."
    gstore_client.create_bucket(BUCKET) #in case it doesn't exist
    filename = "#{BUCKET}-#{Time.now.to_i}.csv"
    gstore_client.put_object(BUCKET, filename, :data => data)
    filename
  end
  
  def self.delete_from_google filename
    gstore_client.delete_object(BUCKET, filename)
  end

end

oauth2.rb

class Oauth2 < ActiveRecord::Base

  def update_token! authorization
    self.refresh_token = authorization.refresh_token if authorization.refresh_token.present?
    self.access_token = authorization.access_token
    self.expires_at = authorization.expires_at
    save!
  end

  def token_hash
    {
      :refresh_token => refresh_token,
      :access_token => access_token,
      :expires_at => expires_at
    }
  end
  
  def expired?
    return true if expires_at.nil?
    Time.now > expires_at
  end
  
end