Return a plain Hash from OutputBuilder for faster serialization

CHANGELOG.md

@@ -7,6 +7,7 @@
 
 #### 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.
 
 

UPGRADING.md

@@ -1,5 +1,13 @@
 # Upgrading Grape Entity
 
+
+### Upgrading to >= 1.2.0
+
+`serializable_hash` and `represent(..., serializable: true)` now return a plain `Hash` or `Array` instead of `Grape::Entity::Exposure::NestingExposure::OutputBuilder`.
+Checks such as `result.is_a?(Grape::Entity::Exposure::NestingExposure::OutputBuilder)` no longer match, and `result.__getobj__` raises `NoMethodError`. Use the result directly as a `Hash` or `Array` instead.
+
+See [#408](https://github.com/ruby-grape/grape-entity/pull/408) for more information.
+
 ### Upgrading to >= 1.1.0
 
 `multi_json` gem is no longer a runtime dependency. Applications that relied on a configured `MultiJson` adapter should add it to their own `Gemfile`.

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/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

@@ -1007,6 +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
 
@@ -1701,7 +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

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