Namespaced serializers

lib/active_model/serializer.rb

@@ -53,7 +53,10 @@ def self.serializer_lookup_chain_for(klass)
       resource_namespace = klass.name.deconstantize
       serializer_class_name = "#{resource_class_name}Serializer"
 
-      chain.push("#{name}::#{serializer_class_name}") if self != ActiveModel::Serializer
+      if self != ActiveModel::Serializer
+        chain.push("#{name}::#{serializer_class_name}")
+        chain.push(*name.deconstantize.split('::').each_with_object([]) { |element, array| array.push((array.last ? array.last + '::' : '') + element) }.reverse.map { |k| k + "::#{serializer_class_name}" })
+      end
       chain.push("#{resource_namespace}::#{serializer_class_name}")
 
       chain

test/serializers/associations_test.rb

@@ -262,6 +262,49 @@ def false
           assert_equal(expected, hash)
         end
       end
+
+      class NamespaceNestedSerializersTest < Minitest::Test
+        Post    = Class.new(::Model)
+        Comment = Class.new(::Model)
+        Author  = Class.new(::Model)
+        Description = Class.new(::Model)
+
+        module SerializerNamespace
+          class PostSerializer < ActiveModel::Serializer
+            has_many :comments
+            belongs_to :author
+            has_one :description
+          end
+          CommentSerializer     = Class.new(ActiveModel::Serializer)
+          AuthorSerializer      = Class.new(ActiveModel::Serializer)
+          DescriptionSerializer = Class.new(ActiveModel::Serializer)
+        end
+
+        def setup
+          @comment = Comment.new
+          @author = Author.new
+          @description = Description.new
+          @post = Post.new(comments: [@comment],
+                           author: @author,
+                           description: @description)
+          @post_serializer = SerializerNamespace::PostSerializer.new(@post)
+        end
+
+        def test_associations_namespaced_resources_new
+          @post_serializer.associations.each do |association|
+            case association.key
+            when :comments
+              assert_instance_of(SerializerNamespace::CommentSerializer, association.serializer.first)
+            when :author
+              assert_instance_of(SerializerNamespace::AuthorSerializer, association.serializer)
+            when :description
+              assert_instance_of(SerializerNamespace::DescriptionSerializer, association.serializer)
+            else
+              flunk "Unknown association: #{key}"
+            end
+          end
+        end
+      end
     end
   end
 end

test/serializers/serializer_for_test.rb

@@ -30,11 +30,15 @@ class SerializerTest < ActiveSupport::TestCase
         module ResourceNamespace
           Post    = Class.new(::Model)
           Comment = Class.new(::Model)
+          Author  = Class.new(::Model)
 
           class PostSerializer < ActiveModel::Serializer
             class CommentSerializer < ActiveModel::Serializer
             end
           end
+
+          class AuthorSerializer < ActiveModel::Serializer
+          end
         end
 
         class MyProfile < Profile
@@ -128,6 +132,12 @@ def test_serializer_for_nested_resource_with_lookup_disabled
           end
           assert_equal nil, serializer
         end
+
+        def test_serializer_for_namespace_nested_resource
+          author = ResourceNamespace::Author.new
+          serializer = ResourceNamespace::PostSerializer.serializer_for(author)
+          assert_equal(ResourceNamespace::AuthorSerializer, serializer)
+        end
       end
     end
   end