Ported JSON serialization from ActiveRecord

lib/mongo_mapper.rb

@@ -11,9 +11,11 @@
 require 'mongo_mapper/key'
 require 'mongo_mapper/finder_options'
 require 'mongo_mapper/save_with_validation'
+require 'mongo_mapper/serialization'
 require 'mongo_mapper/embedded_document'
 require 'mongo_mapper/document'
 
+
 module MongoMapper
   class DocumentNotFound < StandardError; end
 

lib/mongo_mapper/embedded_document.rb

@@ -8,6 +8,7 @@ def self.included(model)
         extend ClassMethods
         include Validatable
         include ActiveSupport::Callbacks
+        include MongoMapper::Serialization
 
         define_callbacks  :before_validation_on_create, :before_validation_on_update,
                           :before_validation,           :after_validation,

lib/mongo_mapper/serialization.rb

@@ -0,0 +1,54 @@
+require 'active_support/json'
+
+module MongoMapper #:nodoc:
+  module Serialization
+    class Serializer #:nodoc:
+      attr_reader :options
+
+      def initialize(record, options = {})
+        @record, @options = record, options.dup
+      end
+
+      def serializable_key_names
+        key_names = @record.send :defined_key_names
+
+        if options[:only]
+          options.delete(:except)
+          key_names = key_names & Array(options[:only]).collect { |n| n.to_s }
+        else
+          options[:except] = Array(options[:except])
+          key_names = key_names - options[:except].collect { |n| n.to_s }
+        end
+
+        key_names
+      end
+
+      def serializable_method_names
+        Array(options[:methods]).inject([]) do |method_attributes, name|
+          method_attributes << name if @record.respond_to?(name.to_s)
+          method_attributes
+        end
+      end
+
+      def serializable_names
+        serializable_key_names + serializable_method_names
+      end
+
+      def serializable_record
+        returning(serializable_record = {}) do
+          serializable_names.each { |name| serializable_record[name] = @record.send(name) }
+        end
+      end
+
+      def serialize
+        # overwrite to implement
+      end
+
+      def to_s(&block)
+        serialize(&block)
+      end
+    end
+  end
+end
+
+require 'mongo_mapper/serializers/json_serializer'

lib/mongo_mapper/serializers/json_serializer.rb

@@ -0,0 +1,77 @@
+module MongoMapper #:nodoc:
+  module Serialization
+    def self.included(base)
+      base.cattr_accessor :include_root_in_json, :instance_writer => false
+      base.extend ClassMethods
+    end
+
+    # Returns a JSON string representing the model. Some configuration is
+    # available through +options+.
+    #
+    # The option <tt>include_root_in_json</tt> controls the top-level behavior of
+    # to_json. When it is <tt>true</tt>, to_json will emit a single root node named
+    # after the object's type. For example:
+    #
+    #   konata = User.find(1)
+    #   User.include_root_in_json = true
+    #   konata.to_json
+    #   # => { "user": {"id": 1, "name": "Konata Izumi", "age": 16,
+    #                   "created_at": "2006/08/01", "awesome": true} }
+    #
+    #   User.include_root_in_json = false
+    #   konata.to_json
+    #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
+    #         "created_at": "2006/08/01", "awesome": true}
+    #
+    # The remainder of the examples in this section assume include_root_in_json is set to
+    # <tt>false</tt>.
+    #
+    # Without any +options+, the returned JSON string will include all
+    # the model's attributes. For example:
+    #
+    #   konata = User.find(1)
+    #   konata.to_json
+    #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
+    #         "created_at": "2006/08/01", "awesome": true}
+    #
+    # The <tt>:only</tt> and <tt>:except</tt> options can be used to limit the attributes
+    # included, and work similar to the +attributes+ method. For example:
+    #
+    #   konata.to_json(:only => [ :id, :name ])
+    #   # => {"id": 1, "name": "Konata Izumi"}
+    #
+    #   konata.to_json(:except => [ :id, :created_at, :age ])
+    #   # => {"name": "Konata Izumi", "awesome": true}
+    #
+    # To include any methods on the model, use <tt>:methods</tt>.
+    #
+    #   konata.to_json(:methods => :permalink)
+    #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
+    #         "created_at": "2006/08/01", "awesome": true,
+    #         "permalink": "1-konata-izumi"}
+    def to_json(options = {})
+      if include_root_in_json
+        "{#{self.class.json_class_name}: #{JsonSerializer.new(self, options).to_s}}"
+      else
+        JsonSerializer.new(self, options).to_s
+      end
+    end
+
+    def from_json(json)
+      self.attributes = ActiveSupport::JSON.decode(json)
+      self
+    end
+
+    class JsonSerializer < MongoMapper::Serialization::Serializer #:nodoc:
+      def serialize
+        serializable_record.to_json
+      end
+    end
+
+    module ClassMethods
+      def json_class_name
+        @json_class_name ||= name.demodulize.underscore.inspect
+      end
+    end
+  end
+end

test/serializers/test_json_serializer.rb

@@ -0,0 +1,104 @@
+require 'test_helper'
+
+class JsonSerializationTest < Test::Unit::TestCase
+  class Contact
+    include MongoMapper::EmbeddedDocument
+    key :name, String
+    key :age, Integer
+    key :created_at, Time
+    key :awesome, Boolean
+    key :preferences, Hash
+  end
+
+  def setup
+    Contact.include_root_in_json = false
+    @contact = Contact.new(
+      :name        => 'Konata Izumi',
+      :age         => 16,
+      :created_at  => Time.utc(2006, 8, 1),
+      :awesome     => true,
+      :preferences => { :shows => 'anime' }
+    )
+  end
+
+  should "include demodulized root" do
+    Contact.include_root_in_json = true
+    assert_match %r{^\{"contact": \{}, @contact.to_json
+  end
+
+  should "encode all encodable attributes" do
+    json = @contact.to_json
+
+    assert_match %r{"name": "Konata Izumi"}, json
+    assert_match %r{"age": 16}, json
+    assert json.include?(%("created_at": #{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))}))
+    assert_match %r{"awesome": true}, json
+    assert_match %r{"preferences": \{"shows": "anime"\}}, json
+  end
+
+  should "allow attribute filtering with only" do
+    json = @contact.to_json(:only => [:name, :age])
+
+    assert_match %r{"name": "Konata Izumi"}, json
+    assert_match %r{"age": 16}, json
+    assert_no_match %r{"awesome"}, json
+    assert_no_match %r{"created_at"}, json
+    assert_no_match %r{"preferences"}, json
+  end
+
+  should "allow attribute filtering with except" do
+    json = @contact.to_json(:except => [:name, :age])
+
+    assert_no_match %r{"name"}, json
+    assert_no_match %r{"age"}, json
+    assert_match %r{"awesome"}, json
+    assert_match %r{"created_at"}, json
+    assert_match %r{"preferences"}, json
+  end
+
+  context "including methods" do
+    setup do
+      def @contact.label; "Has cheezburger"; end
+      def @contact.favorite_quote; "Constraints are liberating"; end
+    end
+
+    should "include single method" do
+      # Single method.
+      assert_match %r{"label": "Has cheezburger"}, @contact.to_json(:only => :name, :methods => :label)
+    end
+
+    should "include multiple methods" do
+      json = @contact.to_json(:only => :name, :methods => [:label, :favorite_quote])
+      assert_match %r{"label": "Has cheezburger"}, json
+      assert_match %r{"favorite_quote": "Constraints are liberating"}, json
+    end
+  end
+
+  context "array of records" do
+    setup do
+      @contacts = [
+        Contact.new(:name => 'David', :age => 39),
+        Contact.new(:name => 'Mary', :age => 14)
+      ]
+    end
+
+    should "allow attribute filtering with only" do
+      assert_equal %([{"name": "David"}, {"name": "Mary"}]), @contacts.to_json(:only => :name)
+    end
+
+    should "allow attribute filtering with except" do
+      json = @contacts.to_json(:except => [:name, :preferences, :awesome, :created_at])
+      assert_equal %([{"age": 39}, {"age": 14}]), json
+    end
+  end
+
+  should "allow options for hash of records" do
+    contacts = {
+      1 => Contact.new(:name => 'David', :age => 39),
+      2 => Contact.new(:name => 'Mary', :age => 14)
+    }
+
+    assert_equal %({"1": {"name": "David"}}), contacts.to_json(:only => [1, :name])
+  end
+
+end

test/test_serializations.rb

@@ -0,0 +1,54 @@
+require 'test_helper'
+
+class SerializationTest < Test::Unit::TestCase
+  def setup
+    @document = Class.new do
+      include MongoMapper::EmbeddedDocument
+      key :name, String
+      key :age, Integer
+      key :awesome, Boolean
+      key :preferences, Hash
+      key :created_at, Time
+    end
+
+    @instance = @document.new(
+      :name        => 'John Doe',
+      :age         => 25,
+      :awesome     => true,
+      :preferences => {:language => 'Ruby'},
+      :created_at  => Time.now.change(:usec => 0)
+    )
+  end
+
+  # [:xml, :json].each do |format|
+  [:json].each do |format|
+    context format do
+      should "be reversable" do
+        serialized = @instance.send("to_#{format}")
+        unserialized = @document.new.send("from_#{format}", serialized)
+
+        assert_equal @instance, unserialized
+      end
+
+      should "allow attribute only filtering" do
+        serialized = @instance.send("to_#{format}", :only => [ :age, :name ])
+        unserialized = @document.new.send("from_#{format}", serialized)
+
+        assert_equal @instance.name, unserialized.name
+        assert_equal @instance.age, unserialized.age
+        assert_nil unserialized.awesome
+        assert_nil unserialized.created_at
+      end
+
+      should "allow attribute except filtering" do
+        serialized = @instance.send("to_#{format}", :except => [ :age, :name ])
+        unserialized = @document.new.send("from_#{format}", serialized)
+
+        assert_nil unserialized.name
+        assert_nil unserialized.age
+        assert_equal @instance.awesome, unserialized.awesome
+      end
+
+    end
+  end
+end