Implement embed in root

lib/active_model/serializable.rb

@@ -3,11 +3,19 @@ module ActiveModel
     def as_json(options={})
       if root = options[:root] || self.root
         hash = { root.to_s => serializable_object }
-        hash[meta_key.to_s] = meta if meta
+        hash.merge!(serializable_data)
         hash
       else
         serializable_object
       end
     end
+
+    def serializable_data
+      if respond_to?(:meta) && meta
+        { meta_key.to_s => meta }
+      else
+        {}
+      end
+    end
   end
 end

lib/active_model/serializer.rb

@@ -70,15 +70,20 @@ module ActiveModel
     def initialize(object, options={})
       @object   = object
       @scope    = options[:scope]
-      @root     = options[:root] || self.class._root
-      @root     = self.class.root_name if @root == true
+      self.root = options[:root]
       @meta_key = options[:meta_key] || :meta
       @meta     = options[@meta_key]
     end
-    attr_accessor :object, :scope, :root, :meta_key, :meta
+    attr_accessor :object, :scope, :meta_key, :meta
+    attr_reader :root
 
     alias read_attribute_for_serialization send
 
+    def root=(root)
+      @root = root || self.class._root
+      @root = self.class.root_name if auto_assign_root?
+    end
+
     def attributes
       self.class._attributes.each_with_object({}) do |name, hash|
         hash[name] = send(name)
@@ -89,8 +94,19 @@ module ActiveModel
       self.class._associations.each_with_object({}) do |association, hash|
         if association.embed_ids?
           hash[association.key] = serialize_ids association
+        elsif association.embed_objects?
+          hash[association.embedded_key] = serialize association
         end
-        if association.embed_objects?
+      end
+    end
+
+    def serializable_data
+      embedded_in_root_associations.merge!(super)
+    end
+
+    def embedded_in_root_associations
+      self.class._associations.each_with_object({}) do |association, hash|
+        if association.embed_in_root?
           hash[association.embedded_key] = serialize association
         end
       end
@@ -120,5 +136,11 @@ module ActiveModel
       hash.merge! associations
     end
     alias serializable_object serializable_hash
+
+    private
+
+    def auto_assign_root?
+      @root == true || !@root && self.class._associations.any? { |a| a.embed_in_root? }
+    end
   end
 end

lib/active_model/serializer/associations.rb

@@ -7,20 +7,20 @@ module ActiveModel
         @name          = name
         @options       = options
 
-        self.embed    = options[:embed]
-        @embed_key    = options[:embed_key] || :id
-        @include      = options[:include]
-        @key          = options[:key]
-        @embedded_key = options[:root]
+        self.embed     = options[:embed]
+        @embed_in_root = @embed_ids && options[:include]
+        @embed_key     = options[:embed_key] || :id
+        @key           = options[:key]
+        @embedded_key  = options[:root]
 
         self.serializer_class = @options[:serializer]
       end
 
-      attr_reader :name, :embed_ids, :embed_objects, :embed_key, :serializer_class, :options
-      attr_accessor :include, :key, :embedded_key
+      attr_reader :name, :embed_ids, :embed_objects, :serializer_class
+      attr_accessor :embed_in_root, :embed_key, :key, :embedded_key, :options
       alias embed_ids? embed_ids
       alias embed_objects? embed_objects
-      alias include? include
+      alias embed_in_root? embed_in_root
 
       def serializer_class=(serializer)
         @serializer_class = serializer.is_a?(String) ? serializer.constantize : serializer
@@ -31,10 +31,6 @@ module ActiveModel
         @embed_objects = embed == :object || embed == :objects
       end
 
-      def embed_objects?
-        @embed_objects || @embed_ids && @include
-      end
-
       def build_serializer(object)
         @serializer_class ||= Serializer.serializer_for(object)