Define entity in serializer for grape_swagger (#9)

* Model entity in serializer definition

* Use constantize for ref

* Fix loading and entity camel_lower

* Update README with example for entity

* Change check for enumarable

* Revert using hash for attributes_to_serialize

* Rename method

* Add changelog entry

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Add RubyGems version badge
 * Handle inherit from a parent serializer
+* Define entity in serializer for grape_swagger (#9)
 
 ## 0.1.1 (2020-07-13)
 

README.md

@@ -125,6 +125,27 @@ class AccountSerializer
 end
 ```
 
+### Entity
+
+You can define the entity of your serializer to generate documentation with the option `entity`.
+The feature was build to work with [grape-swagger](https://github.com/ruby-grape/grape-swagger). 
+For more information about defining a model entity see the [Swagger documentation](https://swagger.io/specification/v2/?sbsearch=array%20response#schema-object).
+
+```ruby
+class AccountSerializer
+  include BrightSerializer::Serializer
+  attribute :id, entity: { type: :string, description: 'The id of the account' }
+  attribute :name
+
+  attribute :friends,
+    entity: { 
+      type: :array, items: { ref: 'FriendSerializer' }, description: 'The list the account friends.'
+     } do |object|
+    FriendSerializer.new(object.friends)
+  end
+end
+```
+
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.

lib/bright_serializer/attribute.rb

@@ -1,14 +1,17 @@
 # frozen_string_literal: true
 
+require_relative 'entity/base'
+
 module BrightSerializer
   class Attribute
-    attr_reader :key, :block, :condition
+    attr_reader :key, :block, :condition, :entity
     attr_accessor :transformed_key
 
-    def initialize(key, condition, &block)
+    def initialize(key, condition, entity, &block)
       @key = key
       @condition = condition
       @block = block
+      @entity = entity ? Entity::Base.new(entity) : nil
     end
 
     def serialize(object, params)

lib/bright_serializer/entity/base.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+require_relative 'parser'
+
+module BrightSerializer
+  module Entity
+    class Base
+      DEFAULT_DEFINITION = { type: :undefined }.freeze
+
+      # https://swagger.io/specification/v2/?sbsearch=array%20response#schema-object
+
+      def initialize(definition)
+        @definition = definition
+      end
+
+      def to_h
+        @definition.transform_keys! { |k| Inflector.camel_lower k.to_s }
+        parse_ref!
+        @definition
+      end
+
+      def parse_ref!
+        object = nested_hash(@definition, 'ref')
+        return unless object
+
+        ref_entity_name = Inflector.constantize(object.delete('ref')).entity_name
+        relation = "#/definitions/#{ref_entity_name}"
+        object['$ref'] = relation
+      end
+
+      def nested_hash(obj, key)
+        if obj.respond_to?(:key?) && obj.key?(key)
+          obj
+        elsif obj.respond_to?(:each)
+          r = nil
+          obj.find { |*a| r = nested_hash(a.last, key) }
+          r
+        end
+      end
+    end
+  end
+end

lib/bright_serializer/entity/parser.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module BrightSerializer
+  module Entity
+    class Parser
+      attr_reader :model
+      attr_reader :endpoint
+
+      def initialize(model, endpoint)
+        @model = model
+        @endpoint = endpoint
+      end
+
+      def call
+        @model.entity
+      end
+    end
+  end
+end

lib/bright_serializer/inflector.rb

@@ -28,5 +28,36 @@ def dash(underscored_word)
       underscored_word.tr!('_', '-')
       underscored_word
     end
+
+    # File activesupport/lib/active_support/inflector/methods.rb, line 271
+    def constantize(camel_cased_word)
+      names = camel_cased_word.split('::')
+
+      # Trigger a built-in NameError exception including the ill-formed constant in the message.
+      Object.const_get(camel_cased_word) if names.empty?
+
+      # Remove the first blank element in case of '::ClassName' notation.
+      names.shift if names.size > 1 && names.first.empty?
+
+      names.inject(Object) do |constant, name|
+        if constant == Object
+          constant.const_get(name)
+        else
+          candidate = constant.const_get(name)
+          next candidate if constant.const_defined?(name, false)
+          next candidate unless Object.const_defined?(name)
+
+          # Go down the ancestors to check if it is owned directly. The check
+          # stops when we reach Object or the end of ancestors tree.
+          constant = constant.ancestors.each_with_object(constant) do |ancestor, const|
+            break const    if ancestor == Object
+            break ancestor if ancestor.const_defined?(name, false)
+          end
+
+          # owner is in Object, so raise
+          constant.const_get(name, false)
+        end
+      end
+    end
   end
 end

lib/bright_serializer/serializer.rb

@@ -4,6 +4,7 @@
 require 'set'
 require_relative 'attribute'
 require_relative 'inflector'
+require_relative 'entity/base'
 
 module BrightSerializer
   module Serializer
@@ -31,7 +32,7 @@ def serialize(object)
     end
 
     def serializable_hash
-      if @object.respond_to?(:size) && !@object.respond_to?(:each_pair)
+      if @object.respond_to?(:each) && !@object.respond_to?(:each_pair)
         @object.map { |o| serialize o }
       else
         serialize(@object)
@@ -57,7 +58,7 @@ def inherited(subclass)
 
       def attributes(*attributes, **options, &block)
         attributes.each do |key|
-          attribute = Attribute.new(key, options[:if], &block)
+          attribute = Attribute.new(key, options[:if], options[:entity], &block)
           attribute.transformed_key = run_transform_key(key)
           @attributes_to_serialize << attribute
         end
@@ -80,6 +81,19 @@ def run_transform_key(input)
           input.to_sym
         end
       end
+
+      def entity
+        {}.tap do |result|
+          @attributes_to_serialize.each do |attribute|
+            entity_value = attribute.entity&.to_h || BrightSerializer::Entity::Base::DEFAULT_DEFINITION
+            result.merge!(attribute.transformed_key => entity_value)
+          end
+        end
+      end
+
+      def entity_name
+        name.split('::').last.downcase
+      end
     end
   end
 end

spec/lib/bright_serializer/entity/base_spec.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+RSpec.describe BrightSerializer::Entity::Base do
+  let(:instance) { described_class.new(type: :string) }
+  let(:entity_class) do
+    Class.new do
+      include BrightSerializer::Serializer
+
+      def self.entity_name
+        'user'
+      end
+    end
+  end
+
+  before do
+    allow(Inflector).to receive(:constantize) { entity_class }
+  end
+
+  describe '#to_h' do
+    subject { instance.to_h }
+
+    it 'return the definition' do
+      expect(subject).to eq('type' => :string)
+    end
+  end
+
+  describe '#parser_ref!' do
+    subject { instance.to_h }
+
+    let(:instance) { described_class.new(ref: 'SomeModule::User') }
+
+    it 'modified @definition' do
+      expect(subject).to eq('$ref' => '#/definitions/user')
+    end
+
+    context 'when deep ref' do
+      let(:instance) do
+        described_class.new(
+          type: :array,
+          items: { 'ref' => 'SomeModule::User' }
+        )
+      end
+
+      it 'modified @definition' do
+        expect(subject).to(
+          eq(
+            'type' => :array,
+            'items' => {
+              '$ref' => '#/definitions/user'
+            }
+          )
+        )
+      end
+    end
+  end
+end

spec/lib/bright_serializer/serializer_entity_spec.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+RSpec.describe BrightSerializer::Serializer do
+  describe '.entity' do
+    subject { serializer_class.entity }
+
+    let(:serializer_class) do
+      Class.new do
+        include BrightSerializer::Serializer
+        attribute :name, entity: { type: :string }
+      end
+    end
+
+    it 'return name with his entity' do
+      expect(subject).to eq(name: { 'type' => :string })
+    end
+
+    context 'when one is undefined' do
+      let(:serializer_class) do
+        Class.new do
+          include BrightSerializer::Serializer
+          attribute :name, entity: { type: :string }
+          attribute :id
+        end
+      end
+
+      it 'return name with his entity' do
+        expect(subject).to eq(id: { type: :undefined }, name: { 'type' => :string })
+      end
+    end
+  end
+
+  describe '.entity_name' do
+    subject { serializer_class.entity_name }
+
+    let(:serializer_class) do
+      Class.new do
+        include BrightSerializer::Serializer
+      end
+    end
+
+    it 'return the class name downcase' do
+      allow(serializer_class).to receive(:name).and_return('BrightSerializer::Serializer::User')
+      expect(subject).to eq('user')
+    end
+  end
+end