vendor/rails/activerecord/lib/active_record/serializers/json_serializer.rb

   1 module ActiveRecord #:nodoc:
   2   module Serialization
   3     def self.included(base)
   4       base.cattr_accessor :include_root_in_json, :instance_writer => false
   5       base.extend ClassMethods
   6     end
   7
   8     # Returns a JSON string representing the model. Some configuration is
   9     # available through +options+.
  10     #
  11     # The option <tt>ActiveRecord::Base.include_root_in_json</tt> controls the
  12     # top-level behavior of to_json. In a new Rails application, it is set to
  13     # <tt>true</tt> in initializers/new_rails_defaults.rb. When it is <tt>true</tt>,
  14     # to_json will emit a single root node named after the object's type. For example:
  15     #
  16     #   konata = User.find(1)
  17     #   ActiveRecord::Base.include_root_in_json = true
  18     #   konata.to_json
  19     #   # => { "user": {"id": 1, "name": "Konata Izumi", "age": 16,
  20     #                   "created_at": "2006/08/01", "awesome": true} }
  21     #
  22     #   ActiveRecord::Base.include_root_in_json = false
  23     #   konata.to_json
  24     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  25     #         "created_at": "2006/08/01", "awesome": true}
  26     #
  27     # The remainder of the examples in this section assume include_root_in_json is set to
  28     # <tt>false</tt>.
  29     #
  30     # Without any +options+, the returned JSON string will include all
  31     # the model's attributes. For example:
  32     #
  33     #   konata = User.find(1)
  34     #   konata.to_json
  35     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  36     #         "created_at": "2006/08/01", "awesome": true}
  37     #
  38     # The <tt>:only</tt> and <tt>:except</tt> options can be used to limit the attributes
  39     # included, and work similar to the +attributes+ method. For example:
  40     #
  41     #   konata.to_json(:only => [ :id, :name ])
  42     #   # => {"id": 1, "name": "Konata Izumi"}
  43     #
  44     #   konata.to_json(:except => [ :id, :created_at, :age ])
  45     #   # => {"name": "Konata Izumi", "awesome": true}
  46     #
  47     # To include any methods on the model, use <tt>:methods</tt>.
  48     #
  49     #   konata.to_json(:methods => :permalink)
  50     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  51     #         "created_at": "2006/08/01", "awesome": true,
  52     #         "permalink": "1-konata-izumi"}
  53     #
  54     # To include associations, use <tt>:include</tt>.
  55     #
  56     #   konata.to_json(:include => :posts)
  57     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  58     #         "created_at": "2006/08/01", "awesome": true,
  59     #         "posts": [{"id": 1, "author_id": 1, "title": "Welcome to the weblog"},
  60     #                   {"id": 2, author_id: 1, "title": "So I was thinking"}]}
  61     #
  62     # 2nd level and higher order associations work as well:
  63     #
  64     #   konata.to_json(:include => { :posts => {
  65     #                                  :include => { :comments => {
  66     #                                                :only => :body } },
  67     #                                  :only => :title } })
  68     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  69     #         "created_at": "2006/08/01", "awesome": true,
  70     #         "posts": [{"comments": [{"body": "1st post!"}, {"body": "Second!"}],
  71     #                    "title": "Welcome to the weblog"},
  72     #                   {"comments": [{"body": "Don't think too hard"}],
  73     #                    "title": "So I was thinking"}]}
  74     def to_json(options = {})
  75       if include_root_in_json
  76         "{#{self.class.json_class_name}: #{JsonSerializer.new(self, options).to_s}}"
  77       else
  78         JsonSerializer.new(self, options).to_s
  79       end
  80     end
  81
  82     def from_json(json)
  83       self.attributes = ActiveSupport::JSON.decode(json)
  84       self
  85     end
  86
  87     class JsonSerializer < ActiveRecord::Serialization::Serializer #:nodoc:
  88       def serialize
  89         serializable_record.to_json
  90       end
  91     end
  92
  93     module ClassMethods
  94       def json_class_name
  95         @json_class_name ||= name.demodulize.underscore.inspect
  96       end
  97     end
  98   end
  99 end