学习 active resource ActiveSupport::JSON.decode(json)

activeresource_abc.rb

  def find(*arguments)
	scope   = arguments.slice!(0)
	options = arguments.slice!(0) || {}

	case scope
	  when :all   then find_every(options)
	  when :first then find_every(options).first
	  when :last  then find_every(options).last
	  when :one   then find_one(options)
	  else             find_single(scope, options)
	end
  end
  
  
  
	# Find a single resource from a one-off URL
	def find_one(options)
	  case from = options[:from]
	  when Symbol
		instantiate_record(get(from, options[:params]))
	  when String
		path = "#{from}#{query_string(options[:params])}"
		instantiate_record(format.decode(connection.get(path, headers).body))  #关键
		end
	end
        
#1. connection.get(path, headers)
#2. format.decode(connection.get(path, headers).body)
#3. instantiate_record(format.decode(connection.get(path, headers).body)) 

#1.


  # An instance of ActiveResource::Connection that is the base \connection to the remote service.
  # The +refresh+ parameter toggles whether or not the \connection is refreshed at every request
  # or not (defaults to <tt>false</tt>).
  def connection(refresh = false)
	if defined?(@connection) || superclass == Object
	  @connection = Connection.new(site, format) if refresh || @connection.nil?
	  @connection.proxy = proxy if proxy
	  @connection.user = user if user
	  @connection.password = password if password
	  @connection.auth_type = auth_type if auth_type
	  @connection.timeout = timeout if timeout
	  @connection.ssl_options = ssl_options if ssl_options
	  @connection
	else
	  superclass.connection
	end
  end
  
#~/.rvm/gems/ruby-2.1.2/gems/activeresource-3.2.17/lib/active_resource/connection.rb
    # Executes a GET request.
    # Used to get (find) resources.
    def get(path, headers = {})
      with_auth { request(:get, path, build_request_headers(headers, :get, self.site.merge(path))) }
    end      
# .body 返回内容

#2. format.decode() ????what?
#~/.rvm/gems/ruby-2.1.2/gems/activeresource-3.2.17/lib/active_resource/formats/json_format.rb
require 'active_support/json'

module ActiveResource
  module Formats
    module JsonFormat
      extend self

      def extension
        "json"
      end

      def mime_type
        "application/json"
      end

      def encode(hash, options = nil)
        ActiveSupport::JSON.encode(hash, options)
      end

      def decode(json)
        Formats.remove_root(ActiveSupport::JSON.decode(json)) # 这他妈是关键
      end
    end
  end
end



#3. ?
def instantiate_record(record, prefix_options = {})
  new(record, true).tap do |resource|
	resource.prefix_options = prefix_options
  end
end