Integrate AMo JSON serializer into AR

3 files changed, 110 insertions, 31 deletions

diff --git a/activemodel/lib/active_model/attributes.rb b/activemodel/lib/active_model/attributes.rb
index 4665525281..ea8c8d5f72 100644
--- a/activemodel/lib/active_model/attributes.rb
+++ b/activemodel/lib/active_model/attributes.rb
@@ -2,6 +2,14 @@ require 'active_support/core_ext/object/instance_variables'
 
 module ActiveModel
   module Attributes
+    def self.append_features(base)
+      unless base.instance_methods.include?('attributes')
+        super
+      else
+        false
+      end
+    end
+
     def attributes
       instance_values
     end
diff --git a/activemodel/lib/active_model/serializer.rb b/activemodel/lib/active_model/serializer.rb
index 7a55921e85..5b603bdbd7 100644
--- a/activemodel/lib/active_model/serializer.rb
+++ b/activemodel/lib/active_model/serializer.rb
@@ -8,6 +8,9 @@ module ActiveModel
     def initialize(serializable, options = nil)
       @serializable = serializable
       @options = options ? options.dup : {}
+
+      @options[:only] = Array.wrap(@options[:only]).map { |n| n.to_s }
+      @options[:except] = Array.wrap(@options[:except]).map { |n| n.to_s }
     end
 
     def serialize
@@ -18,37 +21,40 @@ module ActiveModel
       serialize(&block)
     end
 
-    protected
-      def serializable_attribute_names
-        attribute_names = @serializable.attributes.keys
-
-        if options[:only]
-          only = Array.wrap(options[:only]).map { |n| n.to_s }
-          attribute_names &= only
-        elsif options[:except]
-          except = Array.wrap(options[:except]).map { |n| n.to_s }
-          attribute_names -= except
-        end
-
-        attribute_names
+    # To replicate the behavior in ActiveRecord#attributes,
+    # <tt>:except</tt> takes precedence over <tt>:only</tt>.  If <tt>:only</tt> is not set
+    # for a N level model but is set for the N+1 level models,
+    # then because <tt>:except</tt> is set to a default value, the second
+    # level model can have both <tt>:except</tt> and <tt>:only</tt> set.  So if
+    # <tt>:only</tt> is set, always delete <tt>:except</tt>.
+    def serializable_attribute_names
+      attribute_names = @serializable.attributes.keys.sort
+
+      if options[:only].any?
+        attribute_names &= options[:only]
+      elsif options[:except].any?
+        attribute_names -= options[:except]
       end
 
-      def serializable_method_names
-        Array.wrap(options[:methods]).inject([]) do |methods, name|
-          methods << name if @serializable.respond_to?(name.to_s)
-          methods
-        end
-      end
+      attribute_names
+    end
 
-      def serializable_names
-        serializable_attribute_names + serializable_method_names
+    def serializable_method_names
+      Array.wrap(options[:methods]).inject([]) do |methods, name|
+        methods << name if @serializable.respond_to?(name.to_s)
+        methods
       end
+    end
 
-      def serializable_hash
-        serializable_names.inject({}) { |hash, name|
-          hash[name] = @serializable.send(name)
-          hash
-        }
-      end
+    def serializable_names
+      serializable_attribute_names + serializable_method_names
+    end
+
+    def serializable_hash
+      serializable_names.inject({}) { |hash, name|
+        hash[name] = @serializable.send(name)
+        hash
+      }
+    end
   end
 end
diff --git a/activemodel/lib/active_model/serializers/json.rb b/activemodel/lib/active_model/serializers/json.rb
index 0636e8c330..adf200597d 100644
--- a/activemodel/lib/active_model/serializers/json.rb
+++ b/activemodel/lib/active_model/serializers/json.rb
@@ -16,10 +16,9 @@ module ActiveModel
       class Serializer < ActiveModel::Serializer
         def serializable_hash
           model = super
-          if @serializable.include_root_in_json
-            model = { @serializable.class.model_name.element => model }
-          end
-          model
+          @serializable.include_root_in_json ?
+            { @serializable.class.model_name.element => model } :
+            model
         end
 
         def serialize
@@ -27,6 +26,72 @@ module ActiveModel
         end
       end
 
+      # Returns a JSON string representing the model. Some configuration is
+      # available through +options+.
+      #
+      # The option <tt>ActiveRecord::Base.include_root_in_json</tt> controls the
+      # top-level behavior of to_json. In a new Rails application, it is set to 
+      # <tt>true</tt> in initializers/new_rails_defaults.rb. 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)
+      #   ActiveRecord::Base.include_root_in_json = true
+      #   konata.to_json
+      #   # => { "user": {"id": 1, "name": "Konata Izumi", "age": 16,
+      #                   "created_at": "2006/08/01", "awesome": true} }
+      #
+      #   ActiveRecord::Base.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"}
+      #
+      # To include associations, use <tt>:include</tt>.
+      #
+      #   konata.to_json(:include => :posts)
+      #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
+      #         "created_at": "2006/08/01", "awesome": true,
+      #         "posts": [{"id": 1, "author_id": 1, "title": "Welcome to the weblog"},
+      #                   {"id": 2, author_id: 1, "title": "So I was thinking"}]}
+      #
+      # 2nd level and higher order associations work as well:
+      #
+      #   konata.to_json(:include => { :posts => {
+      #                                  :include => { :comments => {
+      #                                                :only => :body } },
+      #                                  :only => :title } })
+      #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
+      #         "created_at": "2006/08/01", "awesome": true,
+      #         "posts": [{"comments": [{"body": "1st post!"}, {"body": "Second!"}],
+      #                    "title": "Welcome to the weblog"},
+      #                   {"comments": [{"body": "Don't think too hard"}],
+      #                    "title": "So I was thinking"}]}
       def encode_json(encoder)
         Serializer.new(self, encoder.options).to_s
       end