This adds namespace lookup to serializer_for

.travis.yml

@@ -20,7 +20,8 @@ cache:
 
 script:
   - bundle exec rake ci
-
+after_success:
+  - codeclimate-test-reporter
 env:
   global:
     - "JRUBY_OPTS='--dev -J-Xmx1024M --debug'"

lib/action_controller/serialization.rb

@@ -18,6 +18,10 @@ def serialization_scope(scope)
       self._serialization_scope = :current_user
     end
 
+    def namespace_for_serializer
+      @namespace_for_serializer ||= self.class.parent unless self.class.parent == Object
+    end
+
     def serialization_scope
       return unless _serialization_scope && respond_to?(_serialization_scope, true)
 
@@ -30,6 +34,9 @@ def get_serializer(resource, options = {})
           "Please pass 'adapter: false' or see ActiveSupport::SerializableResource.new"
         options[:adapter] = false
       end
+
+      options.fetch(:namespace) { options[:namespace] = namespace_for_serializer }
+
       serializable_resource = ActiveModelSerializers::SerializableResource.new(resource, options)
       serializable_resource.serialization_scope ||= options.fetch(:scope) { serialization_scope }
       serializable_resource.serialization_scope_name = options.fetch(:scope_name) { _serialization_scope }

lib/active_model/serializer.rb

@@ -44,7 +44,7 @@ def self.serializer_for(resource, options = {})
       elsif resource.respond_to?(:to_ary)
         config.collection_serializer
       else
-        options.fetch(:serializer) { get_serializer_for(resource.class) }
+        options.fetch(:serializer) { get_serializer_for(resource.class, options[:namespace]) }
       end
     end
 
@@ -59,13 +59,14 @@ class << self
     end
 
     # @api private
-    def self.serializer_lookup_chain_for(klass)
+    def self.serializer_lookup_chain_for(klass, namespace = nil)
       chain = []
 
       resource_class_name = klass.name.demodulize
       resource_namespace = klass.name.deconstantize
       serializer_class_name = "#{resource_class_name}Serializer"
 
+      chain.push("#{namespace.name}::#{serializer_class_name}") if namespace
       chain.push("#{name}::#{serializer_class_name}") if self != ActiveModel::Serializer
       chain.push("#{resource_namespace}::#{serializer_class_name}")
 
@@ -84,11 +85,12 @@ def self.serializers_cache
     #   1. class name appended with "Serializer"
     #   2. try again with superclass, if present
     #   3. nil
-    def self.get_serializer_for(klass)
+    def self.get_serializer_for(klass, namespace = nil)
       return nil unless config.serializer_lookup_enabled
       serializers_cache.fetch_or_store(klass) do
         # NOTE(beauby): When we drop 1.9.3 support we can lazify the map for perfs.
-        serializer_class = serializer_lookup_chain_for(klass).map(&:safe_constantize).find { |x| x && x < ActiveModel::Serializer }
+        lookup_chain = serializer_lookup_chain_for(klass, namespace)
+        serializer_class = lookup_chain.map(&:safe_constantize).find { |x| x && x < ActiveModel::Serializer }
 
         if serializer_class
           serializer_class

lib/active_model/serializer/reflection.rb

@@ -106,6 +106,10 @@ def value(serializer, include_slice)
       #
       def build_association(parent_serializer, parent_serializer_options, include_slice = {})
         reflection_options = options.dup
+
+        # Pass the parent's namespace onto the child serializer
+        reflection_options[:namespace] ||= parent_serializer_options[:namespace]
+
         association_value = value(parent_serializer, include_slice)
         serializer_class = parent_serializer.class.serializer_for(association_value, reflection_options)
         reflection_options[:include_data] = include_data?(include_slice)

lib/active_model_serializers/serializable_resource.rb

@@ -55,7 +55,7 @@ def serializer
       @serializer ||=
         begin
           @serializer = serializer_opts.delete(:serializer)
-          @serializer ||= ActiveModel::Serializer.serializer_for(resource)
+          @serializer ||= ActiveModel::Serializer.serializer_for(resource, serializer_opts)
 
           if serializer_opts.key?(:each_serializer)
             serializer_opts[:serializer] = serializer_opts.delete(:each_serializer)

test/serializers/serializer_for_with_namespace_test.rb

@@ -0,0 +1,85 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class SerializerForWithNamespaceTest < ActiveSupport::TestCase
+      class Book < ::Model; end
+      class Page < ::Model; end
+      class Publisher < ::Model; end
+
+      module Api
+        module V3
+          class BookSerializer < ActiveModel::Serializer
+            attributes :title, :author_name
+
+            has_many :pages
+            belongs_to :publisher
+          end
+
+          class PageSerializer < ActiveModel::Serializer
+            attributes :number, :text
+
+            belongs_to :book
+          end
+
+          class PublisherSerializer < ActiveModel::Serializer
+            attributes :name
+          end
+        end
+      end
+
+      # class ::BookSerializer < ActiveModel::Serializer
+      #   attributes :title, :author_name
+      # end
+      # test 'resource without a namespace' do
+      #   book = Book.new(title: 'A Post', author_name: 'hello')
+      #
+      #   result = ActiveModelSerializers::SerializableResource.new(book).serializable_hash
+      #
+      #   expected = { title: 'A Post', author_name: 'hello' }
+      #   assert_equal expected, result
+      # end
+
+      test 'resource with namespace' do
+        book = Book.new(title: 'A Post', author_name: 'hi')
+
+        result = ActiveModelSerializers::SerializableResource.new(book, namespace: Api::V3).serializable_hash
+
+        expected = { title: 'A Post', author_name: 'hi', pages: nil, publisher: nil }
+        assert_equal expected, result
+      end
+
+      test 'has_many with nested serializer under the namespace' do
+        page = Page.new(number: 1, text: 'hello')
+        book = Book.new(title: 'A Post', author_name: 'hi', pages: [page])
+
+        result = ActiveModelSerializers::SerializableResource.new(book, namespace: Api::V3).serializable_hash
+
+        expected = {
+          title: 'A Post', author_name: 'hi',
+          publisher: nil,
+          pages: [{
+            number: 1, text: 'hello'
+          }]
+        }
+        assert_equal expected, result
+      end
+
+      test 'belongs_to with nested serializer under the namespace' do
+        publisher = Publisher.new(name: 'Disney')
+        book = Book.new(title: 'A Post', author_name: 'hi', publisher: publisher)
+
+        result = ActiveModelSerializers::SerializableResource.new(book, namespace: Api::V3).serializable_hash
+
+        expected = {
+          title: 'A Post', author_name: 'hi',
+          pages: nil,
+          publisher: {
+            name: 'Disney'
+          }
+        }
+        assert_equal expected, result
+      end
+    end
+  end
+end