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