Railsのas_jsonをもうちょっと便利に使うオプション ref: http://qiita.com/tbaba/items/ea44025b056f708ab0b4

file0.rb

irb(main):033:0> user = User.first
=> #<User id: 1, first_name: ‘Tatsuro’, last_name: ‘Baba’, email: ‘harakirisoul@gmail.com’>
irb(main):034:0> user.as_json
=> {"email"=>"user_1@example.com", "first_name"=>"User1", "id"=>1, "last_name"=>"USER1"}

file1.rb

user.as_json.merge(full_name: user.full_name)

file2.rb

irb(main):035:0> user.as_json(methods: 'full_name')
=> {"email"=>"user_1@example.com", "first_name"=>"User1", "id"=>1, "last_name"=>"USER1”, “full_name”=>”User1 USER1”}

file3.rb

user.as_json.delete_if{|k, v| k == 'email' }

file4.rb

user.as_json(except: 'email')
=> {"first_name"=>"User1", "id"=>1, "last_name"=>"USER1”}

file5.rb

user.as_json(only: ['id', 'first_name', 'last_name'])
=> {"first_name"=>"User1", "id"=>1, "last_name"=>"USER1”}