Refactor: introduce lazy association

Author: bf4

lib/active_model/serializer/association.rb

@@ -1,3 +1,5 @@
+require 'active_model/serializer/lazy_association'
+
 module ActiveModel
   class Serializer
     # This class holds all information about serializer's association.
@@ -10,14 +12,22 @@ class Serializer
     #  Association.new(:comments, { serializer: CommentSummarySerializer })
     #
     class Association < Field
+      attr_reader :lazy_association
+      delegate :include_data?, :virtual_value, to: :lazy_association
+
+      def initialize(*)
+        super
+        @lazy_association = LazyAssociation.new(name, options, block)
+      end
+
       # @return [Symbol]
       def key
         options.fetch(:key, name)
       end
 
-      # @return [ActiveModel::Serializer, nil]
-      def serializer
-        options[:serializer]
+      # @return [True,False]
+      def key?
+        options.key?(:key)
       end
 
       # @return [Hash]
@@ -30,21 +40,30 @@ def meta
         options[:meta]
       end
 
+      def polymorphic?
+        true == options[:polymorphic]
+      end
+
       # @api private
       def serializable_hash(adapter_options, adapter_instance)
-        return options[:virtual_value] if options[:virtual_value]
-        object = serializer && serializer.object
-        return unless object
+        association_serializer = lazy_association.serializer
+        return virtual_value if virtual_value
+        association_object = association_serializer && association_serializer.object
+        return unless association_object
 
-        serialization = serializer.serializable_hash(adapter_options, {}, adapter_instance)
+        serialization = association_serializer.serializable_hash(adapter_options, {}, adapter_instance)
 
-        if options[:polymorphic] && serialization
-          polymorphic_type = object.class.name.underscore
+        if polymorphic? && serialization
+          polymorphic_type = association_object.class.name.underscore
           serialization = { type: polymorphic_type, polymorphic_type.to_sym => serialization }
         end
 
         serialization
       end
+
+      private
+
+      delegate :reflection, to: :lazy_association
     end
   end
 end

lib/active_model/serializer/concerns/caching.rb

@@ -193,12 +193,13 @@ def object_cache_keys(collection_serializer, adapter_instance, include_directive
             cache_keys << object_cache_key(serializer, adapter_instance)
 
             serializer.associations(include_directive).each do |association|
-              if association.serializer.respond_to?(:each)
-                association.serializer.each do |sub_serializer|
+              association_serializer = association.lazy_association.serializer
+              if association_serializer.respond_to?(:each)
+                association_serializer.each do |sub_serializer|
                   cache_keys << object_cache_key(sub_serializer, adapter_instance)
                 end
               else
-                cache_keys << object_cache_key(association.serializer, adapter_instance)
+                cache_keys << object_cache_key(association_serializer, adapter_instance)
               end
             end
           end

lib/active_model/serializer/lazy_association.rb

@@ -0,0 +1,22 @@
+module ActiveModel
+  class Serializer
+    class LazyAssociation < Field
+
+      def serializer
+        options[:serializer]
+      end
+
+      def include_data?
+        options[:include_data]
+      end
+
+      def virtual_value
+        options[:virtual_value]
+      end
+
+      def reflection
+        options[:reflection]
+      end
+    end
+  end
+end

lib/active_model/serializer/reflection.rb

@@ -170,7 +170,11 @@ def build_association(parent_serializer, parent_serializer_options, include_slic
         end
 
         association_block = nil
-        Association.new(name, reflection_options, association_block)
+        reflection_options[:reflection] = self
+        reflection_options[:parent_serializer] = parent_serializer
+        reflection_options[:parent_serializer_options] = parent_serializer_options
+        reflection_options[:include_slice] = include_slice
+        Association.new(name, reflection_options, block)
       end
 
       protected

lib/active_model_serializers/adapter/json_api.rb

@@ -257,7 +257,7 @@ def process_resource(serializer, primary, include_slice = {})
 
       def process_relationships(serializer, include_slice)
         serializer.associations(include_slice).each do |association|
-          process_relationship(association.serializer, include_slice[association.key])
+          process_relationship(association.lazy_association.serializer, include_slice[association.key])
         end
       end
 

lib/active_model_serializers/adapter/json_api/relationship.rb

@@ -15,9 +15,7 @@ def initialize(parent_serializer, serializable_resource_options, association)
         def as_json
           hash = {}
 
-          if association.options[:include_data]
-            hash[:data] = data_for(association)
-          end
+          hash[:data] = data_for(association) if association.include_data?
 
           links = links_for(association)
           hash[:links] = links if links.any?
@@ -36,10 +34,10 @@ def as_json
         private
 
         def data_for(association)
-          serializer = association.serializer
+          serializer = association.lazy_association.serializer
           if serializer.respond_to?(:each)
             serializer.map { |s| ResourceIdentifier.new(s, serializable_resource_options).as_json }
-          elsif (virtual_value = association.options[:virtual_value])
+          elsif (virtual_value = association.virtual_value)
             virtual_value
           elsif serializer && serializer.object
             ResourceIdentifier.new(serializer, serializable_resource_options).as_json

test/serializers/associations_test.rb

@@ -30,18 +30,17 @@ def setup
       def test_has_many_and_has_one
         @author_serializer.associations.each do |association|
           key = association.key
-          serializer = association.serializer
-          options = association.options
+          serializer = association.lazy_association.serializer
 
           case key
           when :posts
-            assert_equal true, options.fetch(:include_data)
+            assert_equal true, association.include_data?
             assert_kind_of(ActiveModelSerializers.config.collection_serializer, serializer)
           when :bio
-            assert_equal true, options.fetch(:include_data)
+            assert_equal true, association.include_data?
             assert_nil serializer
           when :roles
-            assert_equal true, options.fetch(:include_data)
+            assert_equal true, association.include_data?
             assert_kind_of(ActiveModelSerializers.config.collection_serializer, serializer)
           else
             flunk "Unknown association: #{key}"
@@ -56,12 +55,11 @@ def test_has_many_with_no_serializer
         end
         post_serializer_class.new(@post).associations.each do |association|
           key = association.key
-          serializer = association.serializer
-          options = association.options
+          serializer = association.lazy_association.serializer
 
           assert_equal :tags, key
           assert_nil serializer
-          assert_equal [{ id: 'tagid', name: '#hashtagged' }].to_json, options[:virtual_value].to_json
+          assert_equal [{ id: 'tagid', name: '#hashtagged' }].to_json, association.virtual_value.to_json
         end
       end
 
@@ -70,7 +68,7 @@ def test_serializer_options_are_passed_into_associations_serializers
                       .associations
                       .detect { |assoc| assoc.key == :comments }
 
-        comment_serializer = association.serializer.first
+        comment_serializer = association.lazy_association.serializer.first
         class << comment_serializer
           def custom_options
             instance_options
@@ -82,7 +80,7 @@ def custom_options
       def test_belongs_to
         @comment_serializer.associations.each do |association|
           key = association.key
-          serializer = association.serializer
+          serializer = association.lazy_association.serializer
 
           case key
           when :post
@@ -93,7 +91,7 @@ def test_belongs_to
             flunk "Unknown association: #{key}"
           end
 
-          assert_equal true, association.options.fetch(:include_data)
+          assert_equal true, association.include_data?
         end
       end
 
@@ -203,11 +201,11 @@ def test_associations_namespaced_resources
           @post_serializer.associations.each do |association|
             case association.key
             when :comments
-              assert_instance_of(ResourceNamespace::CommentSerializer, association.serializer.first)
+              assert_instance_of(ResourceNamespace::CommentSerializer, association.lazy_association.serializer.first)
             when :author
-              assert_instance_of(ResourceNamespace::AuthorSerializer, association.serializer)
+              assert_instance_of(ResourceNamespace::AuthorSerializer, association.lazy_association.serializer)
             when :description
-              assert_instance_of(ResourceNamespace::DescriptionSerializer, association.serializer)
+              assert_instance_of(ResourceNamespace::DescriptionSerializer, association.lazy_association.serializer)
             else
               flunk "Unknown association: #{key}"
             end
@@ -245,11 +243,11 @@ def test_associations_namespaced_resources
           @post_serializer.associations.each do |association|
             case association.key
             when :comments
-              assert_instance_of(PostSerializer::CommentSerializer, association.serializer.first)
+              assert_instance_of(PostSerializer::CommentSerializer, association.lazy_association.serializer.first)
             when :author
-              assert_instance_of(PostSerializer::AuthorSerializer, association.serializer)
+              assert_instance_of(PostSerializer::AuthorSerializer, association.lazy_association.serializer)
             when :description
-              assert_instance_of(PostSerializer::DescriptionSerializer, association.serializer)
+              assert_instance_of(PostSerializer::DescriptionSerializer, association.lazy_association.serializer)
             else
               flunk "Unknown association: #{key}"
             end
@@ -260,7 +258,7 @@ def test_associations_namespaced_resources
         def test_conditional_associations
           model = Class.new(::Model) do
             attributes :true, :false
-            associations :association
+            associations :something
           end.new(true: true, false: false)
 
           scenarios = [
@@ -284,7 +282,7 @@ def test_conditional_associations
 
           scenarios.each do |s|
             serializer = Class.new(ActiveModel::Serializer) do
-              belongs_to :association, s[:options]
+              belongs_to :something, s[:options]
 
               def true
                 true
@@ -296,7 +294,7 @@ def false
             end
 
             hash = serializable(model, serializer: serializer).serializable_hash
-            assert_equal(s[:included], hash.key?(:association), "Error with #{s[:options]}")
+            assert_equal(s[:included], hash.key?(:something), "Error with #{s[:options]}")
           end
         end
 
@@ -341,8 +339,8 @@ def setup
           @author_serializer = AuthorSerializer.new(@author)
           @inherited_post_serializer = InheritedPostSerializer.new(@post)
           @inherited_author_serializer = InheritedAuthorSerializer.new(@author)
-          @author_associations = @author_serializer.associations.to_a
-          @inherited_author_associations = @inherited_author_serializer.associations.to_a
+          @author_associations = @author_serializer.associations.to_a.sort_by(&:name)
+          @inherited_author_associations = @inherited_author_serializer.associations.to_a.sort_by(&:name)
           @post_associations = @post_serializer.associations.to_a
           @inherited_post_associations = @inherited_post_serializer.associations.to_a
         end
@@ -361,28 +359,35 @@ def setup
 
         test 'a serializer inheriting from another serializer can redefine has_many and has_one associations' do
           expected = [:roles, :bio].sort
-          result = (@inherited_author_associations - @author_associations).map(&:name).sort
+          result = (@inherited_author_associations.map(&:reflection) - @author_associations.map(&:reflection)).map(&:name)
           assert_equal(result, expected)
+          assert_equal [true, false, true], @inherited_author_associations.map(&:polymorphic?)
+          assert_equal [false, false, false], @author_associations.map(&:polymorphic?)
         end
 
         test 'a serializer inheriting from another serializer can redefine belongs_to associations' do
           assert_equal [:author, :comments, :blog], @post_associations.map(&:name)
           assert_equal [:author, :comments, :blog, :comments], @inherited_post_associations.map(&:name)
 
-          refute @post_associations.detect { |assoc| assoc.name == :author }.options.key?(:polymorphic)
-          assert_equal true, @inherited_post_associations.detect { |assoc| assoc.name == :author }.options.fetch(:polymorphic)
+          refute @post_associations.detect { |assoc| assoc.name == :author }.polymorphic?
+          assert @inherited_post_associations.detect { |assoc| assoc.name == :author }.polymorphic?
 
-          refute @post_associations.detect { |assoc| assoc.name == :comments }.options.key?(:key)
+          refute @post_associations.detect { |assoc| assoc.name == :comments }.key?
           original_comment_assoc, new_comments_assoc = @inherited_post_associations.select { |assoc| assoc.name == :comments }
-          refute original_comment_assoc.options.key?(:key)
-          assert_equal :reviews, new_comments_assoc.options.fetch(:key)
-
-          assert_equal @post_associations.detect { |assoc| assoc.name == :blog }, @inherited_post_associations.detect { |assoc| assoc.name == :blog }
+          refute original_comment_assoc.key?
+          assert_equal :reviews, new_comments_assoc.key
+
+          original_blog = @post_associations.detect { |assoc| assoc.name == :blog }
+          inherited_blog = @inherited_post_associations.detect { |assoc| assoc.name == :blog }
+          original_parent_serializer = original_blog.lazy_association.options.delete(:parent_serializer)
+          inherited_parent_serializer = inherited_blog.lazy_association.options.delete(:parent_serializer)
+          assert_equal PostSerializer, original_parent_serializer.class
+          assert_equal InheritedPostSerializer, inherited_parent_serializer.class
         end
 
         test 'a serializer inheriting from another serializer can have an additional association with the same name but with different key' do
           expected = [:author, :comments, :blog, :reviews].sort
-          result = @inherited_post_serializer.associations.map { |a| a.options.fetch(:key, a.name) }.sort
+          result = @inherited_post_serializer.associations.map(&:key).sort
           assert_equal(result, expected)
         end
       end