Return a plain Hash from OutputBuilder for faster serialization

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 #### Features
 
+* [#408](https://github.com/ruby-grape/grape-entity/pull/408): Return a plain `Hash`/`Array` from `serializable_hash` and `represent(..., serializable: true)` instead of an `OutputBuilder` for faster serialization. `Hash === result`, `Array === result` and `case`/`when` against the result now match - [@a5-stable](https://github.com/a5-stable).
 * Your contribution here.
 
 

lib/grape_entity/entity.rb

@@ -190,7 +190,7 @@ def self.inherited(subclass)
     #   field, typically the value is a hash with two fields, type and desc.
     # @option options :merge This option allows you to merge an exposed field to the root
     #
-    # rubocop:disable Layout/LineLength
+    # rubocop:disable-next Layout/LineLength
     def self.expose(*args, &block)
       options = merge_options(args.last.is_a?(Hash) ? args.pop : {})
 
@@ -217,7 +217,6 @@ def self.expose(*args, &block)
       @nesting_stack ||= []
       args.each { |attribute| build_exposure_for_attribute(attribute, @nesting_stack, options, block) }
     end
-    # rubocop:enable Layout/LineLength
 
     def self.build_exposure_for_attribute(attribute, nesting_stack, options, block)
       exposure_list = nesting_stack.empty? ? root_exposures : nesting_stack.last.nested_exposures

lib/grape_entity/exposure/nesting_exposure.rb

@@ -122,7 +122,7 @@ def map_entity_exposures(entity, options)
               result = yield(exposure, new_options)
               out.add(exposure, result)
             end
-          end
+          end.output
         end
       end
     end

lib/grape_entity/exposure/nesting_exposure/nested_exposures.rb

@@ -36,7 +36,7 @@ def clear
             @exposures.clear
           end
 
-          # rubocop:disable Style/DocumentDynamicEvalDefinition
+          # rubocop:disable-next Style/DocumentDynamicEvalDefinition
           %i[
             each
             to_ary to_a
@@ -56,7 +56,6 @@ def #{name}(*args, &block)
               end
             RUBY
           end
-          # rubocop:enable Style/DocumentDynamicEvalDefinition
 
           # Determine if we have any nesting exposures with the same name.
           def deep_complex_nesting?(entity)

lib/grape_entity/exposure/nesting_exposure/output_builder.rb

@@ -4,13 +4,11 @@ module Grape
   class Entity
     module Exposure
       class NestingExposure
-        class OutputBuilder < SimpleDelegator
+        class OutputBuilder
           def initialize(entity)
             @entity = entity
             @output_hash = {}
             @output_collection = []
-
-            super
           end
 
           def add(exposure, result)
@@ -28,29 +26,17 @@ def add(exposure, result)
             end
           end
 
-          def kind_of?(klass)
-            klass == output.class || super
-          end
-          alias is_a? kind_of?
+          # If output_collection contains at least one element we have to represent the output as a collection
+          def output
+            return @output_hash if @output_collection.empty?
 
-          def __getobj__
-            output
+            result = @output_collection.dup
+            result << @output_hash unless @output_hash.empty?
+            result.flatten
           end
 
           private
 
-          # If output_collection contains at least one element we have to represent the output as a collection
-          def output
-            if @output_collection.empty?
-              output = @output_hash
-            else
-              output = @output_collection
-              output << @output_hash unless @output_hash.empty?
-              output.flatten!
-            end
-            output
-          end
-
           # In case if we want to solve collisions providing lambda to :merge option
           def merge_strategy(for_merge)
             if for_merge.respond_to? :call

spec/grape_entity/entity_spec.rb

@@ -33,13 +33,12 @@
         end
 
         it 'makes sure that :format_with as a proc cannot be used with a block' do
-          # rubocop:disable Style/BlockDelimiters
+          # rubocop:disable-next Style/BlockDelimiters
           expect {
             subject.expose :name, format_with: proc {} do
               p 'hi'
             end
           }.to raise_error ArgumentError
-          # rubocop:enable Style/BlockDelimiters
         end
 
         it 'makes sure unknown options are not silently ignored' do
@@ -1008,6 +1007,16 @@ class Parent < Person
               awesome: { just_a_key: 'value', just_another_key: 'value' }
             )
           end
+
+          it 'returns the same result when serializable_hash is called repeatedly' do
+            subject.expose(:tags, merge: true) { |_| %w[a b] }
+            subject.expose(:name)
+
+            entity = subject.represent(name: 'John')
+            expected = ['a', 'b', { name: 'John' }]
+
+            2.times { expect(entity.serializable_hash).to eq(expected) }
+          end
         end
       end
 
@@ -1702,7 +1711,6 @@ class Parent < Person
         subject.expose :my_items
 
         representation = subject.represent(Array.new(4) { Object.new }, serializable: true)
-        expect(representation).to be_kind_of(Grape::Entity::Exposure::NestingExposure::OutputBuilder)
         expect(representation).to be_kind_of(Hash)
         expect(representation).to have_key :my_items
         expect(representation[:my_items]).to be_kind_of Array
@@ -2294,12 +2302,11 @@ class FriendEntity < Grape::Entity
             end
           end
 
-          # rubocop:disable Lint/EmptyBlock
+          # rubocop:disable-next Lint/EmptyBlock
           fresh_class.class_eval do
             expose :first_friend, using: EntitySpec::FriendEntity do |_user, _opts|
             end
           end
-          # rubocop:enable Lint/EmptyBlock
 
           rep = subject.value_for(:first_friend)
           expect(rep).to be_kind_of EntitySpec::FriendEntity

spec/grape_entity/exposure/nesting_exposure/output_builder_spec.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Grape::Entity::Exposure::NestingExposure::OutputBuilder do
+  subject(:builder) { described_class.new(Object.new) }
+
+  let(:merged_array) { double(for_merge: true) }
+  let(:plain) { double(for_merge: false, key: :name) }
+
+  it 'returns the same result when #output is called repeatedly' do
+    builder.add(merged_array, %w[a b])
+    builder.add(plain, 'John')
+
+    expected = ['a', 'b', { name: 'John' }]
+    2.times { expect(builder.output).to eq(expected) }
+  end
+end