# File lib/dm-serializer/to_json.rb, line 16
    def to_json(*args)
      options = args.first || {}
      result = '{ '
      fields = []

      propset = properties_to_serialize(options)

      fields += propset.map do |property|
        "#{property.name.to_json}: #{send(property.getter).to_json}"
      end

      # add methods
      (options[:methods] || []).each do |meth|
        if self.respond_to?(meth)
          fields << "#{meth.to_json}: #{send(meth).to_json}"
        end
      end

      # Note: if you want to include a whole other model via relation, use :methods
      # comments.to_json(:relationships=>{:user=>{:include=>[:first_name],:methods=>[:age]}})
      # add relationships
      # TODO: This needs tests and also needs to be ported to #to_xml and #to_yaml
      (options[:relationships] || {}).each do |rel,opts|
        if self.respond_to?(rel)
          fields << "#{rel.to_json}: #{send(rel).to_json(opts)}"
        end
      end

      result << fields.join(', ')
      result << ' }'
      result
    end