Support for polymorphic associations (#64)

* add hash benchmarking to performance tests

* Add missing attribute in README example

* Disable GC before doing performance test

* Enable oj to AM for fair benchmark test

* Support for polymorphic associations

* Optional dictionary for polymorphic associations

* Added polymorphic record types memoization

* Updated performance tests for polymorphic examples to include jsonapi-rb

Author: vovimayhem

lib/fast_jsonapi/object_serializer.rb

@@ -177,7 +177,8 @@ def has_many(relationship_name, options = {})
           object_method_name: options[:object_method_name] || name,
           serializer: compute_serializer_name(serializer_key),
           relationship_type: :has_many,
-          cached: options[:cached] || false
+          cached: options[:cached] || false,
+          polymorphic: fetch_polymorphic_option(options)
         }
         add_relationship(name, relationship)
       end
@@ -195,7 +196,8 @@ def belongs_to(relationship_name, options = {})
           object_method_name: options[:object_method_name] || name,
           serializer: compute_serializer_name(serializer_key),
           relationship_type: :belongs_to,
-          cached: options[:cached] || true
+          cached: options[:cached] || true,
+          polymorphic: fetch_polymorphic_option(options)
         })
       end
 
@@ -212,7 +214,8 @@ def has_one(relationship_name, options = {})
           object_method_name: options[:object_method_name] || name,
           serializer: compute_serializer_name(serializer_key),
           relationship_type: :has_one,
-          cached: options[:cached] || false
+          cached: options[:cached] || false,
+          polymorphic: fetch_polymorphic_option(options)
         })
       end
 
@@ -222,6 +225,13 @@ def compute_serializer_name(serializer_key)
         return (namespace + serializer_name).to_sym if namespace.present?
         (serializer_key.to_s.classify + 'Serializer').to_sym
       end
+
+      def fetch_polymorphic_option(options)
+        option = options[:polymorphic]
+        return false unless option.present?
+        return option if option.respond_to? :keys
+        {}
+      end
     end
   end
 end

lib/fast_jsonapi/serialization_core.rb

@@ -27,6 +27,30 @@ def ids_hash(ids, record_type)
         id_hash(ids, record_type) # ids variable is just a single id here
       end
 
+      def id_hash_from_record(record, record_types)
+        # memoize the record type within the record_types dictionary, then assigning to record_type:
+        record_type = record_types[record.class] ||= record.class.name.underscore.to_sym
+        { id: record.id.to_s, type: record_type }
+      end
+
+      def ids_hash_from_record_and_relationship(record, relationship)
+        polymorphic = relationship[:polymorphic]
+
+        return ids_hash(
+          record.public_send(relationship[:id_method_name]),
+          relationship[:record_type]
+        ) unless polymorphic
+
+        object_method_name = relationship.fetch(:object_method_name, relationship[:name])
+        return unless associated_object = record.send(object_method_name)
+
+        return associated_object.map do |object|
+          id_hash_from_record object, polymorphic
+        end if associated_object.respond_to? :map
+
+        id_hash_from_record associated_object, polymorphic
+      end
+
       def attributes_hash(record)
         attributes_to_serialize.each_with_object({}) do |(key, method_name), attr_hash|
           attr_hash[key] = record.public_send(method_name)
@@ -42,7 +66,7 @@ def relationships_hash(record, relationships = nil)
           record_type = relationship[:record_type]
           empty_case = relationship[:relationship_type] == :has_many ? [] : nil
           hash[name] = {
-            data: ids_hash(record.public_send(id_method_name), record_type) || empty_case
+            data: ids_hash_from_record_and_relationship(record, relationship) || empty_case
           }
         end
       end

spec/lib/object_serializer_performance_spec.rb

@@ -5,6 +5,10 @@
   include_context 'ams movie class'
   include_context 'jsonapi movie class'
 
+  include_context 'group class'
+  include_context 'ams group class'
+  include_context 'jsonapi group class'
+
   before(:all) { GC.disable }
   after(:all) { GC.enable }
 
@@ -118,4 +122,28 @@ def run_json_benchmark(message, movie_count, our_serializer, ams_serializer, jso
       end
     end
   end
+
+  context 'when comparing with AMS 0.10.x and with polymorphic has_many' do
+    [1, 25, 250, 1000].each do |group_count|
+      speed_factor = 25
+      it "should serialize #{group_count} records at least #{speed_factor} times faster than AMS" do
+        ams_groups = build_ams_groups(group_count)
+        groups = build_groups(group_count)
+        options = {}
+        our_serializer = GroupSerializer.new(groups, options)
+        ams_serializer = ActiveModelSerializers::SerializableResource.new(ams_groups)
+        jsonapi_serializer = JSONAPISerializerB.new(jsonapi_groups)
+
+        message = "Serialize to JSON string #{group_count} with polymorphic has_many"
+        our_json, ams_json, jsonapi_json = run_json_benchmark(message, group_count, our_serializer, ams_serializer, jsonapi_serializer)
+
+        message = "Serialize to Ruby Hash #{group_count} with polymorphic has_many"
+        run_hash_benchmark(message, group_count, our_serializer, ams_serializer, jsonapi_serializer)
+
+        expect(our_json.length).to eq ams_json.length
+        expect { our_serializer.serialized_json }.to perform_faster_than { ams_serializer.to_json }.at_least(speed_factor).times
+        expect { our_serializer.serializable_hash }.to perform_faster_than { ams_serializer.as_json }.at_least(speed_factor).times
+      end
+    end
+  end
 end

spec/lib/serialization_core_spec.rb

@@ -2,6 +2,7 @@
 
 describe FastJsonapi::ObjectSerializer do
   include_context "movie class"
+  include_context 'group class'
 
   context 'when testing class methods of serialization core' do
     it 'returns correct hash when id_hash is called' do
@@ -16,6 +17,12 @@
       expect(result_hash).to be nil
     end
 
+    it 'returns the correct hash when ids_hash_from_record_and_relationship is called for a polymorphic association' do
+      relationship = { name: :groupees, relationship_type: :has_many, polymorphic: {} }
+      results = GroupSerializer.send :ids_hash_from_record_and_relationship, group, relationship
+      expect(results).to include({ id: "1", type: :person }, { id: "2", type: :group })
+    end
+
     it 'returns correct hash when ids_hash is called' do
       inputs = [{ids: %w(1 2 3), record_type: :movie}, {ids: %w(x y z), record_type: 'person'}]
       inputs.each do |hash|
@@ -80,5 +87,4 @@
       expect(included_records.size).to eq 3
     end
   end
-
 end

spec/shared/contexts/ams_group_context.rb

@@ -0,0 +1,87 @@
+RSpec.shared_context 'ams group class' do
+  before(:context) do
+    # models
+    class AMSPerson < ActiveModelSerializers::Model
+      attr_accessor :id, :first_name, :last_name
+    end
+
+    class AMSGroup < ActiveModelSerializers::Model
+      attr_accessor :id, :name, :groupees
+    end
+
+    # serializers
+    class AMSPersonSerializer < ActiveModel::Serializer
+      type 'person'
+      attributes :first_name, :last_name
+    end
+
+    class AMSGroupSerializer < ActiveModel::Serializer
+      type 'group'
+      attributes :name
+      has_many :groupees
+    end
+  end
+
+  after(:context) do
+    classes_to_remove = %i[AMSPerson AMSGroup AMSPersonSerializer AMSGroupSerializer]
+    classes_to_remove.each do |klass_name|
+      Object.send(:remove_const, klass_name) if Object.constants.include?(klass_name)
+    end
+  end
+
+  let(:ams_groups) do
+    group_count = 0
+    person_count = 0
+    3.times.map do |i|
+      group = AMSGroup.new
+      group.id = group_count + 1
+      group.name = "Test Group #{group.id}"
+      group_count = group.id
+
+      person = AMSPerson.new
+      person.id = person_count + 1
+      person.last_name = "Last Name #{person.id}"
+      person.first_name = "First Name #{person.id}"
+      person_count = person.id
+
+      child_group = AMSGroup.new
+      child_group.id = group_count + 1
+      child_group.name = "Test Group #{child_group.id}"
+      group_count = child_group.id
+
+      group.groupees = [person, child_group]
+      group
+    end
+  end
+
+  let(:ams_person) do
+    ams_person = AMSPerson.new
+    ams_person.id = 3
+    ams_person
+  end
+
+  def build_ams_groups(count)
+    group_count = 0
+    person_count = 0
+    count.times.map do |i|
+      group = AMSGroup.new
+      group.id = group_count + 1
+      group.name = "Test Group #{group.id}"
+      group_count = group.id
+
+      person = AMSPerson.new
+      person.id = person_count + 1
+      person.last_name = "Last Name #{person.id}"
+      person.first_name = "First Name #{person.id}"
+      person_count = person.id
+
+      child_group = AMSGroup.new
+      child_group.id = group_count + 1
+      child_group.name = "Test Group #{child_group.id}"
+      group_count = child_group.id
+
+      group.groupees = [person, child_group]
+      group
+    end
+  end
+end

spec/shared/contexts/group_context.rb

@@ -0,0 +1,131 @@
+RSpec.shared_context 'group class' do
+
+  # Person, Group Classes and serializers
+  before(:context) do
+    # models
+    class Person
+      attr_accessor :id, :first_name, :last_name
+    end
+
+    class Group
+      attr_accessor :id, :name, :groupees # Let's assume groupees can be Person or Group objects
+    end
+
+    # serializers
+    class PersonSerializer
+      include FastJsonapi::ObjectSerializer
+      set_type :person
+      attributes :first_name, :last_name
+    end
+
+    class GroupSerializer
+      include FastJsonapi::ObjectSerializer
+      set_type :group
+      attributes :name
+      has_many :groupees, polymorphic: true
+    end
+  end
+
+
+  # Namespaced PersonSerializer
+  before(:context) do
+    # namespaced model stub
+    module AppName
+      module V1
+        class PersonSerializer
+          include FastJsonapi::ObjectSerializer
+          # to test if compute_serializer_name works
+        end
+      end
+    end
+  end
+
+  # Movie and Actor struct
+  before(:context) do
+    PersonStruct = Struct.new(
+      :id, :first_name, :last_name
+    )
+
+    GroupStruct = Struct.new(
+      :id, :name, :groupees, :groupee_ids
+    )
+  end
+
+  after(:context) do
+    classes_to_remove = %i[
+      Person
+      PersonSerializer
+      Group
+      GroupSerializer
+      AppName::V1::PersonSerializer
+      PersonStruct
+      GroupStruct
+    ]
+    classes_to_remove.each do |klass_name|
+      Object.send(:remove_const, klass_name) if Object.constants.include?(klass_name)
+    end
+  end
+
+  let(:group_struct) do
+    group = GroupStruct.new
+    group[:id] = 1
+    group[:name] = 'Group 1'
+    group[:groupees] = []
+
+    person = PersonStruct.new
+    person[:id] = 1
+    person[:last_name] = "Last Name 1"
+    person[:first_name] = "First Name 1"
+
+    child_group = GroupStruct.new
+    child_group[:id] = 2
+    child_group[:name] = 'Group 2'
+
+    group.groupees = [person, child_group]
+    group
+  end
+
+  let(:group) do
+    group = Group.new
+    group.id = 1
+    group.name = 'Group 1'
+
+    person = Person.new
+    person.id = 1
+    person.last_name = "Last Name 1"
+    person.first_name = "First Name 1"
+
+    child_group = Group.new
+    child_group.id = 2
+    child_group.name = 'Group 2'
+
+    group.groupees = [person, child_group]
+    group
+  end
+
+  def build_groups(count)
+    group_count = 0
+    person_count = 0
+
+    count.times.map do |i|
+      group = Group.new
+      group.id = group_count + 1
+      group.name = "Test Group #{group.id}"
+      group_count = group.id
+
+      person = Person.new
+      person.id = person_count + 1
+      person.last_name = "Last Name #{person.id}"
+      person.first_name = "First Name #{person.id}"
+      person_count = person.id
+
+      child_group = Group.new
+      child_group.id = group_count + 1
+      child_group.name = "Test Group #{child_group.id}"
+      group_count = child_group.id
+
+      group.groupees = [person, child_group]
+      group
+    end
+  end
+end