vendor/rails/activesupport/lib/active_support/json/encoders/hash.rb

   1 class Hash
   2   # Returns a JSON string representing the hash.
   3   #
   4   # Without any +options+, the returned JSON string will include all
   5   # the hash keys. For example:
   6   #
   7   #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json
   8   #   # => {"name": "Konata Izumi", 1: 2, "age": 16}
   9   #
  10   # The keys in the JSON string are unordered due to the nature of hashes.
  11   #
  12   # The <tt>:only</tt> and <tt>:except</tt> options can be used to limit the
  13   # attributes included, and will accept 1 or more hash keys to include/exclude.
  14   #
  15   #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json(:only => [:name, 'age'])
  16   #   # => {"name": "Konata Izumi", "age": 16}
  17   #
  18   #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json(:except => 1)
  19   #   # => {"name": "Konata Izumi", "age": 16}
  20   #
  21   # The +options+ also filter down to any hash values. This is particularly
  22   # useful for converting hashes containing ActiveRecord objects or any object
  23   # that responds to options in their <tt>to_json</tt> method. For example:
  24   #
  25   #   users = User.find(:all)
  26   #   { :users => users, :count => users.size }.to_json(:include => :posts)
  27   #
  28   # would pass the <tt>:include => :posts</tt> option to <tt>users</tt>,
  29   # allowing the posts association in the User model to be converted to JSON
  30   # as well.
  31   def to_json(options = {}) #:nodoc:
  32     hash_keys = self.keys
  33
  34     if options[:except]
  35       hash_keys = hash_keys - Array(options[:except])
  36     elsif options[:only]
  37       hash_keys = hash_keys & Array(options[:only])
  38     end
  39
  40     returning result = '{' do
  41       result << hash_keys.map do |key|
  42         "#{ActiveSupport::JSON.encode(key)}: #{ActiveSupport::JSON.encode(self[key], options)}"
  43       end * ', '
  44       result << '}'
  45     end
  46   end
  47 end