Add basic JSON serializer to AMo

3 files changed, 106 insertions, 0 deletions

diff --git a/activemodel/lib/active_model.rb b/activemodel/lib/active_model.rb
index 048f542239..544121c593 100644
--- a/activemodel/lib/active_model.rb
+++ b/activemodel/lib/active_model.rb
@@ -38,6 +38,10 @@ module ActiveModel
   autoload :TestCase, 'active_model/test_case'
   autoload :Validations, 'active_model/validations'
   autoload :ValidationsRepairHelper, 'active_model/validations_repair_helper'
+
+  module Serializers
+    autoload :JSON, 'active_model/serializers/json'
+  end
 end
 
 I18n.load_path << File.dirname(__FILE__) + '/active_model/locale/en.yml'
diff --git a/activemodel/lib/active_model/serializers/json.rb b/activemodel/lib/active_model/serializers/json.rb
new file mode 100644
index 0000000000..60b5cbe948
--- /dev/null
+++ b/activemodel/lib/active_model/serializers/json.rb
@@ -0,0 +1,38 @@
+require 'active_support/json'
+require 'active_support/core_ext/class/attribute_accessors'
+require 'active_support/core_ext/hash/except'
+require 'active_support/core_ext/hash/slice'
+
+module ActiveModel
+  module Serializers
+    module JSON
+      extend ActiveSupport::Concern
+      include ActiveModel::Attributes
+
+      included do
+        cattr_accessor :include_root_in_json, :instance_writer => false
+      end
+
+      def encode_json(encoder)
+        options = encoder.options || {}
+
+        hash = if options[:only]
+          only = Array.wrap(options[:only]).map { |attr| attr.to_s }
+          attributes.slice(*only)
+        elsif options[:except]
+          except = Array.wrap(options[:except]).map { |attr| attr.to_s }
+          attributes.except(*except)
+        else
+          attributes
+        end
+
+        hash = { self.class.model_name.element => hash } if include_root_in_json
+        ActiveSupport::JSON.encode(hash)
+      end
+
+      def as_json(options = nil)
+        self
+      end
+    end
+  end
+end
diff --git a/activemodel/test/cases/json_serialization_test.rb b/activemodel/test/cases/json_serialization_test.rb
new file mode 100644
index 0000000000..abcec67a85
--- /dev/null
+++ b/activemodel/test/cases/json_serialization_test.rb
@@ -0,0 +1,64 @@
+require 'cases/helper'
+
+class JsonSerializationTest < ActiveModel::TestCase
+  class Contact
+    extend ActiveModel::Naming
+    include ActiveModel::Serializers::JSON
+    attr_accessor :name, :age, :created_at, :awesome, :preferences
+  end
+
+  def setup
+    @contact = Contact.new
+    @contact.name = 'Konata Izumi'
+    @contact.age = 16
+    @contact.created_at = Time.utc(2006, 8, 1)
+    @contact.awesome = true
+    @contact.preferences = { 'shows' => 'anime' }
+  end
+
+  test "should include root in json" do
+    begin
+      Contact.include_root_in_json = true
+      json = @contact.to_json
+
+      assert_match %r{^\{"contact":\{}, 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
+    ensure
+      Contact.include_root_in_json = false
+    end
+  end
+
+  test "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
+
+  test "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":true}, json
+    assert !json.include?(%("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))}))
+    assert_no_match %r{"preferences":\{"shows":"anime"\}}, json
+  end
+
+  test "should allow attribute filtering with except" do
+    json = @contact.to_json(:except => [:name, :age])
+
+    assert_no_match %r{"name":"Konata Izumi"}, json
+    assert_no_match %r{"age":16}, json
+    assert_match %r{"awesome":true}, json
+    assert json.include?(%("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))}))
+    assert_match %r{"preferences":\{"shows":"anime"\}}, json
+  end
+end