From 8482abfac716e9281ddbed4782869d2bff1dee9a Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Mon, 31 Aug 2015 02:32:38 +0200
Subject: [PATCH 01/14] Move `id` and `json_api_type` methods from `Serializer`
 to `JsonApi`.

---
 lib/active_model/serializer.rb                | 14 --------
 .../serializer/adapter/json_api.rb            | 32 +++++++++++++------
 test/serializers/attributes_test.rb           |  6 ----
 3 files changed, 22 insertions(+), 30 deletions(-)

diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index a9f0e756c..e2aa0cff6 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -146,18 +146,6 @@ def json_key
       @root || object.class.model_name.to_s.underscore
     end
 
-    def id
-      object.id if object
-    end
-
-    def json_api_type
-      if config.jsonapi_resource_type == :plural
-        object.class.model_name.plural
-      else
-        object.class.model_name.singular
-      end
-    end
-
     def attributes(options = {})
       attributes =
         if options[:fields]
@@ -166,8 +154,6 @@ def attributes(options = {})
           self.class._attributes.dup
         end
 
-      attributes += options[:required_fields] if options[:required_fields]
-
       attributes.each_with_object({}) do |name, hash|
         unless self.class._fragmented
           hash[name] = send(name)
diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 1b55a8121..ff10c2b3e 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -44,19 +44,34 @@ def fragment_cache(cached_hash, non_cached_hash)
 
         private
 
+        def resource_identifier(serializer)
+          type = if ActiveModel::Serializer.config.jsonapi_resource_type == :plural
+                   serializer.object.class.model_name.plural
+                 else
+                   serializer.object.class.model_name.singular
+                 end
+          id = serializer.object.id.to_s
+
+          { id: id, type: type }
+        end
+
         def add_relationships(resource, name, serializers)
           resource[:relationships] ||= {}
           resource[:relationships][name] ||= { data: [] }
-          resource[:relationships][name][:data] += serializers.map { |serializer| { type: serializer.json_api_type, id: serializer.id.to_s } }
+          resource[:relationships][name][:data] += serializers.map { |serializer| resource_identifier(serializer) }
         end
 
         def add_relationship(resource, name, serializer, val=nil)
           resource[:relationships] ||= {}
-          resource[:relationships][name] = { data: val }
 
-          if serializer && serializer.object
-            resource[:relationships][name][:data] = { type: serializer.json_api_type, id: serializer.id.to_s }
-          end
+          resource[:relationships][name] ||= {}
+          resource[:relationships][name][:data] = if val
+                                                    val
+                                                  elsif serializer && serializer.object
+                                                    resource_identifier(serializer)
+                                                  else
+                                                    nil
+                                                  end
         end
 
         def add_included(resource_name, serializers, parent = nil)
@@ -100,15 +115,12 @@ def attributes_for_serializer(serializer, options)
 
         def resource_object_for(serializer, options)
           options[:fields] = @fieldset && @fieldset.fields_for(serializer)
-          options[:required_fields] = [:id, :json_api_type]
 
           cache_check(serializer) do
             attributes = serializer.attributes(options)
+            attributes.delete(:id)
 
-            result = {
-              id: attributes.delete(:id).to_s,
-              type: attributes.delete(:json_api_type)
-            }
+            result = resource_identifier(serializer)
 
             result[:attributes] = attributes if attributes.any?
             result
diff --git a/test/serializers/attributes_test.rb b/test/serializers/attributes_test.rb
index 8b039df91..e0a0981fc 100644
--- a/test/serializers/attributes_test.rb
+++ b/test/serializers/attributes_test.rb
@@ -23,12 +23,6 @@ def test_attributes_with_fields_option
                      @profile_serializer.attributes(fields: [:name]))
       end
 
-      def test_required_fields
-        assert_equal({name: 'Name 1', description: 'Description 1'},
-                     @profile_serializer.attributes(fields: [:name, :description], required_fields: [:name]))
-
-      end
-
       def test_attributes_inheritance_definition
         assert_equal([:id, :body], @serializer_klass._attributes)
       end

From f95f7369f07a9543efd5b7bbcb3e40e309762260 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Mon, 31 Aug 2015 03:24:03 +0200
Subject: [PATCH 02/14] Refactor `add_resource_relationship`.

---
 .../serializer/adapter/json_api.rb            | 45 ++++++-------------
 1 file changed, 14 insertions(+), 31 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index ff10c2b3e..2447ca037 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -55,25 +55,6 @@ def resource_identifier(serializer)
           { id: id, type: type }
         end
 
-        def add_relationships(resource, name, serializers)
-          resource[:relationships] ||= {}
-          resource[:relationships][name] ||= { data: [] }
-          resource[:relationships][name][:data] += serializers.map { |serializer| resource_identifier(serializer) }
-        end
-
-        def add_relationship(resource, name, serializer, val=nil)
-          resource[:relationships] ||= {}
-
-          resource[:relationships][name] ||= {}
-          resource[:relationships][name][:data] = if val
-                                                    val
-                                                  elsif serializer && serializer.object
-                                                    resource_identifier(serializer)
-                                                  else
-                                                    nil
-                                                  end
-        end
-
         def add_included(resource_name, serializers, parent = nil)
           unless serializers.respond_to?(:each)
             return unless serializers.object
@@ -148,22 +129,24 @@ def check_assoc(assoc)
         def add_resource_relationships(attrs, serializer, options = {})
           options[:add_included] = options.fetch(:add_included, true)
 
+          attrs[:relationships] ||= {} if serializer.associations.any?
           serializer.associations.each do |association|
             key = association.key
             serializer = association.serializer
             opts = association.options
-
-            attrs[:relationships] ||= {}
-
-            if serializer.respond_to?(:each)
-              add_relationships(attrs, key, serializer)
-            else
-              if opts[:virtual_value]
-                add_relationship(attrs, key, nil, opts[:virtual_value])
-              else
-                add_relationship(attrs, key, serializer)
-              end
-            end
+            value = if serializer.respond_to?(:each)
+                      serializer.map { |s| resource_identifier(s) }
+                    else
+                      if opts[:virtual_value]
+                        opts[:virtual_value]
+                      elsif serializer && serializer.object
+                        resource_identifier(serializer)
+                      else
+                        nil
+                      end
+                    end
+
+            attrs[:relationships][association.key] = { data: value }
 
             if options[:add_included]
               Array(serializer).each do |s|

From 343f8b96bd663a32efa9678a7525b7de12aaf720 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Mon, 31 Aug 2015 06:25:20 +0200
Subject: [PATCH 03/14] Fix bug preventing id overriding.

---
 lib/active_model/serializer/adapter/json_api.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 2447ca037..4566accb8 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -50,7 +50,8 @@ def resource_identifier(serializer)
                  else
                    serializer.object.class.model_name.singular
                  end
-          id = serializer.object.id.to_s
+          id = serializer.id.to_s if serializer.respond_to?('id')
+          id ||= serializer.object.id.to_s
 
           { id: id, type: type }
         end

From d9c680599a366f3982b2df18eb98c3364ed70585 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 01:41:29 +0200
Subject: [PATCH 04/14] Refactor.

---
 .../serializer/adapter/json_api.rb            | 46 +++++++++----------
 1 file changed, 21 insertions(+), 25 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 4566accb8..23ed0fa15 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -50,8 +50,7 @@ def resource_identifier(serializer)
                  else
                    serializer.object.class.model_name.singular
                  end
-          id = serializer.id.to_s if serializer.respond_to?('id')
-          id ||= serializer.object.id.to_s
+          id = serializer.respond_to?('id') ? serializer.id.to_s : serializer.object.id.to_s
 
           { id: id, type: type }
         end
@@ -85,25 +84,18 @@ def add_included(resource_name, serializers, parent = nil)
 
         def attributes_for_serializer(serializer, options)
           if serializer.respond_to?(:each)
-            result = []
-            serializer.each do |object|
-              result << resource_object_for(object, options)
-            end
+            serializer.map { |s| resource_object_for(s, options) }
           else
-            result = resource_object_for(serializer, options)
+            resource_object_for(serializer, options)
           end
-          result
         end
 
         def resource_object_for(serializer, options)
           options[:fields] = @fieldset && @fieldset.fields_for(serializer)
 
           cache_check(serializer) do
-            attributes = serializer.attributes(options)
-            attributes.delete(:id)
-
             result = resource_identifier(serializer)
-
+            attributes = serializer.attributes(options).except(:id)
             result[:attributes] = attributes if attributes.any?
             result
           end
@@ -127,25 +119,29 @@ def check_assoc(assoc)
           end
         end
 
+        def resource_relationship_value(serializer, options = {})
+          if serializer.respond_to?(:each)
+            serializer.map { |s| resource_identifier(s) }
+          else
+            if options[:virtual_value]
+              options[:virtual_value]
+            elsif serializer.object
+              resurce_identifier(serializer)
+            else
+              nil
+            end
+          end
+        end
+
         def add_resource_relationships(attrs, serializer, options = {})
           options[:add_included] = options.fetch(:add_included, true)
 
-          attrs[:relationships] ||= {} if serializer.associations.any?
+          attrs[:relationships] = {} if serializer.associations.any?
           serializer.associations.each do |association|
             key = association.key
             serializer = association.serializer
-            opts = association.options
-            value = if serializer.respond_to?(:each)
-                      serializer.map { |s| resource_identifier(s) }
-                    else
-                      if opts[:virtual_value]
-                        opts[:virtual_value]
-                      elsif serializer && serializer.object
-                        resource_identifier(serializer)
-                      else
-                        nil
-                      end
-                    end
+            options = association.options
+            value = resource_relationship_value(serializer, options)
 
             attrs[:relationships][association.key] = { data: value }
 

From c4faafdebc195372d4f36143476524288923a039 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 09:58:48 +0200
Subject: [PATCH 05/14] Refactor `resource_identifier`.

---
 .../serializer/adapter/json_api.rb            | 40 +++++++++++--------
 1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 23ed0fa15..fb9bfed21 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -44,13 +44,25 @@ def fragment_cache(cached_hash, non_cached_hash)
 
         private
 
+        def resource_identifier_type(serializer)
+          if ActiveModel::Serializer.config.jsonapi_resource_type == :singular
+            serializer.object.class.model_name.singular
+          else
+            serializer.object.class.model_name.plural
+          end
+        end
+
+        def resource_identifier_id(serializer)
+          if serializer.respond_to?('id')
+            serializer.id.to_s
+          else
+            serializer.object.id.to_s
+          end
+        end
+
         def resource_identifier(serializer)
-          type = if ActiveModel::Serializer.config.jsonapi_resource_type == :plural
-                   serializer.object.class.model_name.plural
-                 else
-                   serializer.object.class.model_name.singular
-                 end
-          id = serializer.respond_to?('id') ? serializer.id.to_s : serializer.object.id.to_s
+          type = resource_identifier_type(serializer)
+          id   = resource_identifier_id(serializer)
 
           { id: id, type: type }
         end
@@ -125,8 +137,8 @@ def resource_relationship_value(serializer, options = {})
           else
             if options[:virtual_value]
               options[:virtual_value]
-            elsif serializer.object
-              resurce_identifier(serializer)
+            elsif serializer && serializer.object
+              resource_identifier(serializer)
             else
               nil
             end
@@ -135,19 +147,13 @@ def resource_relationship_value(serializer, options = {})
 
         def add_resource_relationships(attrs, serializer, options = {})
           options[:add_included] = options.fetch(:add_included, true)
-
           attrs[:relationships] = {} if serializer.associations.any?
           serializer.associations.each do |association|
-            key = association.key
-            serializer = association.serializer
-            options = association.options
-            value = resource_relationship_value(serializer, options)
-
+            value = resource_relationship_value(association.serializer, association.options)
             attrs[:relationships][association.key] = { data: value }
-
             if options[:add_included]
-              Array(serializer).each do |s|
-                add_included(key, s)
+              Array(association.serializer).each do |s|
+                add_included(association.key, s)
               end
             end
           end

From 04012052a6e881d82083849af0fe1850d3180017 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 15:39:29 +0200
Subject: [PATCH 06/14] Fix `'id'` -> `:id`.

---
 lib/active_model/serializer/adapter/json_api.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index fb9bfed21..fb6560d83 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -53,7 +53,7 @@ def resource_identifier_type(serializer)
         end
 
         def resource_identifier_id(serializer)
-          if serializer.respond_to?('id')
+          if serializer.respond_to?(:id)
             serializer.id.to_s
           else
             serializer.object.id.to_s

From f7612f2542112841c1ea1275af737ac19356c247 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 16:52:43 +0200
Subject: [PATCH 07/14] Further refactor/streamline method names.

---
 .../serializer/adapter/json_api.rb            | 131 +++++++++---------
 1 file changed, 67 insertions(+), 64 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index fb6560d83..4dc8db0b4 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -31,8 +31,10 @@ def serializable_hash(options = nil)
 
             add_links(options)
           else
-            @hash[:data] = attributes_for_serializer(serializer, options)
-            add_resource_relationships(@hash[:data], serializer)
+            @hash[:data] = attributes_for(serializer, options)
+            relationships = relationships_for(serializer)
+            @hash[:data][:relationships] = relationships if relationships.any?
+            add_included_relationships(serializer)
           end
           @hash
         end
@@ -44,7 +46,7 @@ def fragment_cache(cached_hash, non_cached_hash)
 
         private
 
-        def resource_identifier_type(serializer)
+        def resource_identifier_type_for(serializer)
           if ActiveModel::Serializer.config.jsonapi_resource_type == :singular
             serializer.object.class.model_name.singular
           else
@@ -52,19 +54,69 @@ def resource_identifier_type(serializer)
           end
         end
 
-        def resource_identifier_id(serializer)
+        def resource_identifier_id_for(serializer)
           if serializer.respond_to?(:id)
-            serializer.id.to_s
+            serializer.id
           else
-            serializer.object.id.to_s
+            serializer.object.id
           end
         end
 
-        def resource_identifier(serializer)
-          type = resource_identifier_type(serializer)
-          id   = resource_identifier_id(serializer)
+        def resource_identifier_for(serializer)
+          type = resource_identifier_type_for(serializer)
+          id   = resource_identifier_id_for(serializer)
 
-          { id: id, type: type }
+          { id: id.to_s, type: type }
+        end
+
+        def attributes_for(serializer, options)
+          if serializer.respond_to?(:each)
+            serializer.map { |s| resource_object_for(s, options) }
+          else
+            resource_object_for(serializer, options)
+          end
+        end
+
+        def resource_object_for(serializer, options)
+          options[:fields] = @fieldset && @fieldset.fields_for(serializer)
+
+          cache_check(serializer) do
+            result = resource_identifier_for(serializer)
+            attributes = serializer.attributes(options).except(:id)
+            result[:attributes] = attributes if attributes.any?
+            result
+          end
+        end
+
+        def relationship_value_for(serializer, options = {})
+          if serializer.respond_to?(:each)
+            serializer.map { |s| resource_identifier_for(s) }
+          else
+            if options[:virtual_value]
+              options[:virtual_value]
+            elsif serializer && serializer.object
+              resource_identifier_for(serializer)
+            else
+              nil
+            end
+          end
+        end
+
+        def relationships_for(serializer)
+          relationships = {}
+          serializer.associations.each do |association|
+            value = relationship_value_for(association.serializer, association.options)
+            relationships[association.key] = { data: value }
+          end
+          relationships
+        end
+
+        def add_included_relationships(serializer)
+          serializer.associations.each do |association|
+            Array(association.serializer).each do |assoc_serializer|
+              add_included(association.key, assoc_serializer)
+            end
+          end
         end
 
         def add_included(resource_name, serializers, parent = nil)
@@ -77,9 +129,9 @@ def add_included(resource_name, serializers, parent = nil)
             @hash[:included] ||= []
 
             serializers.each do |serializer|
-              attrs = attributes_for_serializer(serializer, @options)
-
-              add_resource_relationships(attrs, serializer, add_included: false)
+              attrs = attributes_for(serializer, @options)
+              relationships = relationships_for(serializer)
+              attrs[:relationships] = relationships if relationships.any?
 
               @hash[:included].push(attrs) unless @hash[:included].include?(attrs)
             end
@@ -87,29 +139,8 @@ def add_included(resource_name, serializers, parent = nil)
 
           serializers.each do |serializer|
             serializer.associations.each do |association|
-              serializer = association.serializer
-
-              add_included(association.key, serializer, resource_path) if serializer
-            end if include_nested_assoc? resource_path
-          end
-        end
-
-        def attributes_for_serializer(serializer, options)
-          if serializer.respond_to?(:each)
-            serializer.map { |s| resource_object_for(s, options) }
-          else
-            resource_object_for(serializer, options)
-          end
-        end
-
-        def resource_object_for(serializer, options)
-          options[:fields] = @fieldset && @fieldset.fields_for(serializer)
-
-          cache_check(serializer) do
-            result = resource_identifier(serializer)
-            attributes = serializer.attributes(options).except(:id)
-            result[:attributes] = attributes if attributes.any?
-            result
+              add_included(association.key, association.serializer, resource_path) if association.serializer
+            end if include_nested_assoc?(resource_path)
           end
         end
 
@@ -131,34 +162,6 @@ def check_assoc(assoc)
           end
         end
 
-        def resource_relationship_value(serializer, options = {})
-          if serializer.respond_to?(:each)
-            serializer.map { |s| resource_identifier(s) }
-          else
-            if options[:virtual_value]
-              options[:virtual_value]
-            elsif serializer && serializer.object
-              resource_identifier(serializer)
-            else
-              nil
-            end
-          end
-        end
-
-        def add_resource_relationships(attrs, serializer, options = {})
-          options[:add_included] = options.fetch(:add_included, true)
-          attrs[:relationships] = {} if serializer.associations.any?
-          serializer.associations.each do |association|
-            value = resource_relationship_value(association.serializer, association.options)
-            attrs[:relationships][association.key] = { data: value }
-            if options[:add_included]
-              Array(association.serializer).each do |s|
-                add_included(association.key, s)
-              end
-            end
-          end
-        end
-
         def add_links(options)
           links = @hash.fetch(:links) { {} }
           resources = serializer.instance_variable_get(:@resource)

From 91c5cbe0b9e8351d5f7baa18c57167e7f777ae38 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 17:57:30 +0200
Subject: [PATCH 08/14] Cleanup `add_included`.

---
 .../serializer/adapter/json_api.rb            | 39 ++++++++++---------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 4dc8db0b4..78d1fd5dc 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -9,6 +9,11 @@ def initialize(serializer, options = {})
           super
           @hash = { data: [] }
 
+          @options[:include] ||= []
+          if @options[:include].is_a?(String)
+            @options[:include] = @options[:include].split(',')
+          end
+
           if fields = options.delete(:fields)
             @fieldset = ActiveModel::Serializer::Fieldset.new(fields, serializer.json_key)
           else
@@ -119,47 +124,43 @@ def add_included_relationships(serializer)
           end
         end
 
-        def add_included(resource_name, serializers, parent = nil)
-          unless serializers.respond_to?(:each)
-            return unless serializers.object
-            serializers = Array(serializers)
+        def add_included(resource_name, serializer, parent = nil)
+          if serializer.respond_to?(:each)
+            serializer.each { |s| add_included(resource_name, s, parent) }
+            return
+          else
+            return unless serializer.object
           end
+
           resource_path = [parent, resource_name].compact.join('.')
+
           if include_assoc?(resource_path)
             @hash[:included] ||= []
 
-            serializers.each do |serializer|
-              attrs = attributes_for(serializer, @options)
-              relationships = relationships_for(serializer)
-              attrs[:relationships] = relationships if relationships.any?
+            attrs = attributes_for(serializer, @options)
+            relationships = relationships_for(serializer)
+            attrs[:relationships] = relationships if relationships.any?
 
-              @hash[:included].push(attrs) unless @hash[:included].include?(attrs)
-            end
+            @hash[:included].push(attrs) unless @hash[:included].include?(attrs)
           end
 
-          serializers.each do |serializer|
+          if include_nested_assoc?(resource_path)
             serializer.associations.each do |association|
               add_included(association.key, association.serializer, resource_path) if association.serializer
-            end if include_nested_assoc?(resource_path)
+            end
           end
         end
 
         def include_assoc?(assoc)
-          return false unless @options[:include]
           check_assoc("#{assoc}$")
         end
 
         def include_nested_assoc?(assoc)
-          return false unless @options[:include]
           check_assoc("#{assoc}.")
         end
 
         def check_assoc(assoc)
-          include_opt = @options[:include]
-          include_opt = include_opt.split(',') if include_opt.is_a?(String)
-          include_opt.any? do |s|
-            s.match(/^#{assoc.gsub('.', '\.')}/)
-          end
+          @options[:include].any? { |s| s.match(/^#{assoc.gsub('.', '\.')}/) }
         end
 
         def add_links(options)

From bae4951e058059c6bb205d21cfba433671e64be2 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 20:15:27 +0200
Subject: [PATCH 09/14] Further cleanup `included_for`.

---
 .../serializer/adapter/json_api.rb            | 52 +++++++++----------
 1 file changed, 25 insertions(+), 27 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 78d1fd5dc..812a2b103 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -39,7 +39,8 @@ def serializable_hash(options = nil)
             @hash[:data] = attributes_for(serializer, options)
             relationships = relationships_for(serializer)
             @hash[:data][:relationships] = relationships if relationships.any?
-            add_included_relationships(serializer)
+            included = included_for(serializer)
+            @hash[:included] = included if included.any?
           end
           @hash
         end
@@ -116,38 +117,35 @@ def relationships_for(serializer)
           relationships
         end
 
-        def add_included_relationships(serializer)
-          serializer.associations.each do |association|
-            Array(association.serializer).each do |assoc_serializer|
-              add_included(association.key, assoc_serializer)
-            end
-          end
+        def included_for(serializer)
+          serializer.associations.flat_map { |assoc| _included_for(assoc.key, assoc.serializer) }.uniq
         end
 
-        def add_included(resource_name, serializer, parent = nil)
+        def _included_for(resource_name, serializer, parent = nil)
           if serializer.respond_to?(:each)
-            serializer.each { |s| add_included(resource_name, s, parent) }
-            return
+            serializer.flat_map { |s| _included_for(resource_name, s, parent) }.uniq
           else
-            return unless serializer.object
-          end
-
-          resource_path = [parent, resource_name].compact.join('.')
-
-          if include_assoc?(resource_path)
-            @hash[:included] ||= []
-
-            attrs = attributes_for(serializer, @options)
-            relationships = relationships_for(serializer)
-            attrs[:relationships] = relationships if relationships.any?
-
-            @hash[:included].push(attrs) unless @hash[:included].include?(attrs)
-          end
+            result = []
+            if serializer && serializer.object
+              resource_path = [parent, resource_name].compact.join('.')
+
+              if include_assoc?(resource_path)
+                attrs = attributes_for(serializer, @options)
+                relationships = relationships_for(serializer)
+                attrs[:relationships] = relationships if relationships.any?
+                result.push(attrs)
+              end
 
-          if include_nested_assoc?(resource_path)
-            serializer.associations.each do |association|
-              add_included(association.key, association.serializer, resource_path) if association.serializer
+              if include_nested_assoc?(resource_path)
+                serializer.associations.each do |association|
+                  if association.serializer
+                    result.concat(_included_for(association.key, association.serializer, resource_path))
+                    result.uniq!
+                  end
+                end
+              end
             end
+            result
           end
         end
 

From c593adbcb23c98f428e3101fcb682d0b552971bb Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 20:46:18 +0200
Subject: [PATCH 10/14] Further cleanup `add_included`.

---
 .../serializer/adapter/json_api.rb            | 26 +++++++++----------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 812a2b103..23b41b2df 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -36,7 +36,7 @@ def serializable_hash(options = nil)
 
             add_links(options)
           else
-            @hash[:data] = attributes_for(serializer, options)
+            @hash[:data] = resource_objects_for(serializer, options)
             relationships = relationships_for(serializer)
             @hash[:data][:relationships] = relationships if relationships.any?
             included = included_for(serializer)
@@ -75,15 +75,7 @@ def resource_identifier_for(serializer)
           { id: id.to_s, type: type }
         end
 
-        def attributes_for(serializer, options)
-          if serializer.respond_to?(:each)
-            serializer.map { |s| resource_object_for(s, options) }
-          else
-            resource_object_for(serializer, options)
-          end
-        end
-
-        def resource_object_for(serializer, options)
+        def resource_object_for(serializer, options = {})
           options[:fields] = @fieldset && @fieldset.fields_for(serializer)
 
           cache_check(serializer) do
@@ -94,6 +86,14 @@ def resource_object_for(serializer, options)
           end
         end
 
+        def resource_objects_for(serializer, options)
+          if serializer.respond_to?(:each)
+            serializer.map { |s| resource_object_for(s, options) }
+          else
+            resource_object_for(serializer, options)
+          end
+        end
+
         def relationship_value_for(serializer, options = {})
           if serializer.respond_to?(:each)
             serializer.map { |s| resource_identifier_for(s) }
@@ -130,10 +130,10 @@ def _included_for(resource_name, serializer, parent = nil)
               resource_path = [parent, resource_name].compact.join('.')
 
               if include_assoc?(resource_path)
-                attrs = attributes_for(serializer, @options)
+                resource_object = resource_object_for(serializer, @options)
                 relationships = relationships_for(serializer)
-                attrs[:relationships] = relationships if relationships.any?
-                result.push(attrs)
+                resource_object[:relationships] = relationships if relationships.any?
+                result.push(resource_object)
               end
 
               if include_nested_assoc?(resource_path)

From a8a0566d29dc6ac2bd248aa2eb10f6ac1f8c69b4 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 21:16:00 +0200
Subject: [PATCH 11/14] Refactor `relationships_for`.

---
 lib/active_model/serializer/adapter/json_api.rb | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 23b41b2df..767c9c26f 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -109,12 +109,7 @@ def relationship_value_for(serializer, options = {})
         end
 
         def relationships_for(serializer)
-          relationships = {}
-          serializer.associations.each do |association|
-            value = relationship_value_for(association.serializer, association.options)
-            relationships[association.key] = { data: value }
-          end
-          relationships
+          serializer.associations.map { |association| [ association.key, { data: relationship_value_for(association.serializer, association.options) } ] }.to_h
         end
 
         def included_for(serializer)

From f8c553a0edeae111533050c109b0cd0565ff4348 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Tue, 1 Sep 2015 21:18:27 +0200
Subject: [PATCH 12/14] Cleanup.

---
 lib/active_model/serializer/adapter/json_api.rb | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 767c9c26f..6b87caaa9 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -36,10 +36,11 @@ def serializable_hash(options = nil)
 
             add_links(options)
           else
-            @hash[:data] = resource_objects_for(serializer, options)
+            resource_objects = resource_objects_for(serializer, options)
             relationships = relationships_for(serializer)
-            @hash[:data][:relationships] = relationships if relationships.any?
             included = included_for(serializer)
+            @hash[:data] = resource_objects
+            @hash[:data][:relationships] = relationships if relationships.any?
             @hash[:included] = included if included.any?
           end
           @hash
@@ -109,7 +110,7 @@ def relationship_value_for(serializer, options = {})
         end
 
         def relationships_for(serializer)
-          serializer.associations.map { |association| [ association.key, { data: relationship_value_for(association.serializer, association.options) } ] }.to_h
+         Hash[serializer.associations.map { |association| [ association.key, { data: relationship_value_for(association.serializer, association.options) } ] }]
         end
 
         def included_for(serializer)

From 3793f3ff4b00b89d6731c01a3b9e93744c5bfe59 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Wed, 2 Sep 2015 19:27:40 +0200
Subject: [PATCH 13/14] Rename `resource_objects_for` to `primary_data_for`.

---
 lib/active_model/serializer/adapter/json_api.rb | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 6b87caaa9..9a8118bfe 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -36,10 +36,10 @@ def serializable_hash(options = nil)
 
             add_links(options)
           else
-            resource_objects = resource_objects_for(serializer, options)
+            primary_data = primary_data_for(serializer, options)
             relationships = relationships_for(serializer)
             included = included_for(serializer)
-            @hash[:data] = resource_objects
+            @hash[:data] = primary_data
             @hash[:data][:relationships] = relationships if relationships.any?
             @hash[:included] = included if included.any?
           end
@@ -87,7 +87,7 @@ def resource_object_for(serializer, options = {})
           end
         end
 
-        def resource_objects_for(serializer, options)
+        def primary_data_for(serializer, options)
           if serializer.respond_to?(:each)
             serializer.map { |s| resource_object_for(s, options) }
           else
@@ -126,10 +126,10 @@ def _included_for(resource_name, serializer, parent = nil)
               resource_path = [parent, resource_name].compact.join('.')
 
               if include_assoc?(resource_path)
-                resource_object = resource_object_for(serializer, @options)
+                primary_data = primary_data_for(serializer, @options)
                 relationships = relationships_for(serializer)
-                resource_object[:relationships] = relationships if relationships.any?
-                result.push(resource_object)
+                primary_data[:relationships] = relationships if relationships.any?
+                result.push(primary_data)
               end
 
               if include_nested_assoc?(resource_path)

From f27f13ccc15664b1df2f683aa9fd28d89c1b1ed0 Mon Sep 17 00:00:00 2001
From: Lucas Hosseini <lucas.hosseini@gmail.com>
Date: Sun, 6 Sep 2015 19:18:36 +0200
Subject: [PATCH 14/14] Fix style.

---
 .../serializer/adapter/json_api.rb            | 46 +++++++++----------
 1 file changed, 21 insertions(+), 25 deletions(-)

diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 974e4c63a..ac3bf4a11 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -14,7 +14,8 @@ def initialize(serializer, options = {})
             @options[:include] = @options[:include].split(',')
           end
 
-          if fields = options.delete(:fields)
+          fields = options.delete(:fields)
+          if fields
             @fieldset = ActiveModel::Serializer::Fieldset.new(fields, serializer.json_key)
           else
             @fieldset = options[:fieldset]
@@ -48,7 +49,7 @@ def serializable_hash(options = nil)
 
         def fragment_cache(cached_hash, non_cached_hash)
           root = false if @options.include?(:include)
-          JsonApi::FragmentCache.new().fragment_cache(root, cached_hash, non_cached_hash)
+          JsonApi::FragmentCache.new.fragment_cache(root, cached_hash, non_cached_hash)
         end
 
         private
@@ -103,14 +104,12 @@ def relationship_value_for(serializer, options = {})
               options[:virtual_value]
             elsif serializer && serializer.object
               resource_identifier_for(serializer)
-            else
-              nil
             end
           end
         end
 
         def relationships_for(serializer)
-         Hash[serializer.associations.map { |association| [ association.key, { data: relationship_value_for(association.serializer, association.options) } ] }]
+          Hash[serializer.associations.map { |association| [association.key, { data: relationship_value_for(association.serializer, association.options) }] }]
         end
 
         def included_for(serializer)
@@ -121,24 +120,23 @@ def _included_for(resource_name, serializer, parent = nil)
           if serializer.respond_to?(:each)
             serializer.flat_map { |s| _included_for(resource_name, s, parent) }.uniq
           else
+            return [] unless serializer && serializer.object
             result = []
-            if serializer && serializer.object
-              resource_path = [parent, resource_name].compact.join('.')
-
-              if include_assoc?(resource_path)
-                primary_data = primary_data_for(serializer, @options)
-                relationships = relationships_for(serializer)
-                primary_data[:relationships] = relationships if relationships.any?
-                result.push(primary_data)
-              end
+            resource_path = [parent, resource_name].compact.join('.')
+
+            if include_assoc?(resource_path)
+              primary_data = primary_data_for(serializer, @options)
+              relationships = relationships_for(serializer)
+              primary_data[:relationships] = relationships if relationships.any?
+              result.push(primary_data)
+            end
 
-              if include_nested_assoc?(resource_path)
-                serializer.associations.each do |association|
-                  if association.serializer
-                    result.concat(_included_for(association.key, association.serializer, resource_path))
-                    result.uniq!
-                  end
-                end
+            if include_nested_assoc?(resource_path)
+              non_empty_associations = serializer.associations.select(&:serializer)
+
+              non_empty_associations.each do |association|
+                result.concat(_included_for(association.key, association.serializer, resource_path))
+                result.uniq!
               end
             end
             result
@@ -160,9 +158,7 @@ def check_assoc(assoc)
         def add_links(options)
           links = @hash.fetch(:links) { {} }
           collection = serializer.object
-          if is_paginated?(collection)
-            @hash[:links] = add_pagination_links(links, collection, options)
-          end
+          @hash[:links] = add_pagination_links(links, collection, options) if paginated?(collection)
         end
 
         def add_pagination_links(links, collection, options)
@@ -170,7 +166,7 @@ def add_pagination_links(links, collection, options)
           links.update(pagination_links)
         end
 
-        def is_paginated?(collection)
+        def paginated?(collection)
           collection.respond_to?(:current_page) &&
             collection.respond_to?(:total_pages) &&
             collection.respond_to?(:size)