Google Drive APIへの接続

google_drive_api.rb

require 'google/apis/drive_v3'
require 'googleauth'
require 'googleauth/stores/file_token_store'
require 'fileutils'

OOB_URI = 'urn:ietf:wg:oauth:2.0:oob'
APPLICATION_NAME = 'Drive API Ruby Quickstart'
CLIENT_SECRETS_PATH = 'client_secret.json'

# ファイル名もgoogle serviceの名前に合わせて変更する。(この名前は任意の値でOK)
CREDENTIALS_PATH = File.join(Dir.home, '.credentials',
                             "drive-ruby-quickstart.yaml")
# 他のgoogle serviceにアクセスしたい場合は、ここを変更する
SCOPE = Google::Apis::DriveV3::AUTH_DRIVE_METADATA_READONLY

# main以外のメソッドは他のサービスのアクセスでも再利用可能
def get_authorizer
  FileUtils.mkdir_p(File.dirname(CREDENTIALS_PATH))
  client_id = Google::Auth::ClientId.from_file(CLIENT_SECRETS_PATH)
  token_store = Google::Auth::Stores::FileTokenStore.new(file: CREDENTIALS_PATH)
  authorizer = Google::Auth::UserAuthorizer.new(
    client_id, SCOPE, token_store)
  authorizer
end

def retrieve_code
  authorizer = get_authorizer
  url = authorizer.get_authorization_url(base_url: OOB_URI)
  puts "Open the following URL in the browser and enter the resulting code after authorization"
  puts url
end

def store_credentials(code)
  authorizer = get_authorizer
  user_id = 'default'
  credentials = authorizer.get_credentials(user_id)
  if credentials.nil?
    authorizer.get_and_store_credentials_from_code(user_id: user_id, code: code, base_url: OOB_URI)
  end
end

def get_credentials
  authorizer = get_authorizer
  user_id = 'default'
  credentials = authorizer.get_credentials(user_id)
  credentials
end

def main
  # Initialize the API
  service = Google::Apis::DriveV3::DriveService.new
  service.client_options.application_name = APPLICATION_NAME
  service.authorization = get_credentials
  # List the 10 most recently modified files.
  response = service.list_files(page_size: 10,
                                fields: 'nextPageToken, files(id, name)')
  puts 'Files:'
  puts 'No files found' if response.files.empty?
  response.files.each do |file|
    puts "#{file.name} (#{file.id})"
  end
end

#retrieve_code
#code = nil
#store_credentials(code) unless code.nil?
main

retrieve_codeを実行するとURLが出力される
そのURLをブラウザでアクセスるとcodeが発行される
そのcodeをもとに、store_credentialsを呼ぶと、接続のためのcredentialsが保存される
その後mainを呼ぶと、Driveにアクセスできる