has_one returns arrays with roots pluralized

lib/active_model/serializer.rb

@@ -164,7 +164,12 @@ end
            association.serializer_class <= ArraySerializer)
         associated_data.map { |elem| association.build_serializer(elem).serializable_hash }
       else
-        association.build_serializer(associated_data).serializable_object
+        serializable_obj = association.build_serializer(associated_data).serializable_object
+        if !(association.serializer_class && association.serializer_class <= ArraySerializer)
+          serializable_obj = [serializable_obj]
+          serializable_obj.compact!
+        end
+        serializable_obj
       end
     end
 

lib/active_model/serializer/associations.rb

@@ -17,7 +17,6 @@ module ActiveModel
         @embed_in_root = options.fetch(:embed_in_root) { options.fetch(:include) { CONFIG.embed_in_root } }
         @embed_key     = options[:embed_key] || :id
         @key           = options[:key]
-        @embedded_key  = options[:root] || name
 
         self.serializer_class = @options[:serializer]
       end
@@ -43,16 +42,18 @@ module ActiveModel
       end
 
       class HasOne < Association
-        def initialize(*args)
+        def initialize(name, *args)
           super
-          @key  ||= "#{name}_id"
+          @embedded_key = "#{@options[:root] || name}".pluralize
+          @key ||= "#{name}_id"
         end
       end
 
       class HasMany < Association
-        def initialize(*args)
+        def initialize(name, *args)
           super
-          @key ||= "#{name.singularize}_ids"
+          @embedded_key = @options[:root] || name
+          @key ||= "#{name.to_s.singularize}_ids"
         end
       end
     end

test/integration/active_record/active_record_test.rb

@@ -17,7 +17,7 @@ module ActiveModel
             ar_comments: [{ body: 'what a dumb post', ar_tags: [{ name: 'short' }, { name: 'whiny' }] },
                           { body: 'i liked it', ar_tags: [{:name=>"short"}, {:name=>"happy"}] }],
             ar_tags: [{ name: 'short' }, { name: 'whiny' }, { name: 'happy' }],
-            ar_section: { 'name' => 'ruby' }
+            'ar_sections' => [{ 'name' => 'ruby' }]
           }
         }, post_serializer.as_json)
       end
@@ -51,7 +51,7 @@ module ActiveModel
             ar_comments: [{ body: 'what a dumb post', ar_tags: [{ name: 'short' }, { name: 'whiny' }] },
                           { body: 'i liked it', ar_tags: [{:name=>"short"}, {:name=>"happy"}] }],
             ar_tags: [{ name: 'short' }, { name: 'whiny' }, { name: 'happy' }],
-            ar_section: { 'name' => 'ruby' }
+            'ar_sections' => [{ 'name' => 'ruby' }]
           }, post_serializer.as_json)
         end
       end

test/unit/active_model/serializer/has_one_test.rb

@@ -50,7 +50,7 @@ module ActiveModel
         @association.embed = :objects
 
         assert_equal({
-          name: 'Name 1', email: 'mail@server.com', profile: { name: 'N1', description: 'D1' }
+          name: 'Name 1', email: 'mail@server.com', 'profiles' => [{ name: 'N1', description: 'D1' }]
         }, @user_serializer.serializable_hash)
       end
 
@@ -58,7 +58,7 @@ module ActiveModel
         @association.embed = :objects
 
         assert_equal({
-          'user' => { name: 'Name 1', email: 'mail@server.com', profile: { name: 'N1', description: 'D1' } }
+          'user' => { name: 'Name 1', email: 'mail@server.com', 'profiles' => [{ name: 'N1', description: 'D1' }] }
         }, @user_serializer.as_json)
       end
 
@@ -84,7 +84,7 @@ module ActiveModel
         end
 
         assert_equal({
-          'user' => { name: 'Name 1', email: 'mail@server.com', profile: nil }
+          'user' => { name: 'Name 1', email: 'mail@server.com', 'profiles' => [] }
         }, @user_serializer.as_json)
       end
 
@@ -93,7 +93,7 @@ module ActiveModel
         @association.embedded_key = 'root'
 
         assert_equal({
-          name: 'Name 1', email: 'mail@server.com', 'root' => { name: 'N1', description: 'D1' }
+          name: 'Name 1', email: 'mail@server.com', 'root' => [{ name: 'N1', description: 'D1' }]
         }, @user_serializer.serializable_hash)
       end
 
@@ -112,7 +112,7 @@ module ActiveModel
 
         assert_equal({
           'user' => { name: 'Name 1', email: 'mail@server.com', 'profile_id' => @user.profile.object_id },
-          profile: { name: 'N1', description: 'D1' }
+          'profiles' => [{ name: 'N1', description: 'D1' }]
         }, @user_serializer.as_json)
       end
 
@@ -129,7 +129,7 @@ module ActiveModel
 
         assert_equal({
           'user' => { name: 'Name 1', email: 'mail@server.com', 'profile_id' => @user.profile.object_id },
-          profile: { name: 'fake' }
+          'profiles' => [{ name: 'fake' }]
         }, @user_serializer.as_json)
       end
     end