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     # Without any +options+, the returned JSON string will include all
  12     # the model's attributes. For example:
  13     #
  14     #   konata = User.find(1)
  15     #   konata.to_json
  16     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  17     #         "created_at": "2006/08/01", "awesome": true}
  18     #
  19     # The <tt>:only</tt> and <tt>:except</tt> options can be used to limit the attributes
  20     # included, and work similar to the +attributes+ method. For example:
  21     #
  22     #   konata.to_json(:only => [ :id, :name ])
  23     #   # => {"id": 1, "name": "Konata Izumi"}
  24     #
  25     #   konata.to_json(:except => [ :id, :created_at, :age ])
  26     #   # => {"name": "Konata Izumi", "awesome": true}
  27     #
  28     # To include any methods on the model, use <tt>:methods</tt>.
  29     #
  30     #   konata.to_json(:methods => :permalink)
  31     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  32     #         "created_at": "2006/08/01", "awesome": true,
  33     #         "permalink": "1-konata-izumi"}
  34     #
  35     # To include associations, use <tt>:include</tt>.
  36     #
  37     #   konata.to_json(:include => :posts)
  38     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  39     #         "created_at": "2006/08/01", "awesome": true,
  40     #         "posts": [{"id": 1, "author_id": 1, "title": "Welcome to the weblog"},
  41     #                   {"id": 2, author_id: 1, "title": "So I was thinking"}]}
  42     #
  43     # 2nd level and higher order associations work as well:
  44     #
  45     #   konata.to_json(:include => { :posts => {
  46     #                                  :include => { :comments => {
  47     #                                                :only => :body } },
  48     #                                  :only => :title } })
  49     #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
  50     #         "created_at": "2006/08/01", "awesome": true,
  51     #         "posts": [{"comments": [{"body": "1st post!"}, {"body": "Second!"}],
  52     #                    "title": "Welcome to the weblog"},
  53     #                   {"comments": [{"body": "Don't think too hard"}],
  54     #                    "title": "So I was thinking"}]}
  55     def to_json(options = {})
  56       if include_root_in_json
  57         "{#{self.class.json_class_name}: #{JsonSerializer.new(self, options).to_s}}"
  58       else
  59         JsonSerializer.new(self, options).to_s
  60       end
  61     end
  62
  63     def from_json(json)
  64       self.attributes = ActiveSupport::JSON.decode(json)
  65       self
  66     end
  67
  68     class JsonSerializer < ActiveRecord::Serialization::Serializer #:nodoc:
  69       def serialize
  70         serializable_record.to_json
  71       end
  72     end
  73
  74     module ClassMethods
  75       def json_class_name
  76         @json_class_name ||= name.demodulize.underscore.inspect
  77       end
  78     end
  79   end
  80 end