Merge pull request #116 from guidoprincess/root-node-inheritance

Root node inheritance

Author: dblock

.rubocop_todo.yml

@@ -12,7 +12,7 @@ Metrics/AbcSize:
 # Offense count: 1
 # Configuration parameters: CountComments.
 Metrics/ClassLength:
-  Max: 323
+  Max: 330
 
 # Offense count: 5
 Metrics/CyclomaticComplexity:

CHANGELOG.md

@@ -2,6 +2,7 @@
 ============
 
 * [#114](https://github.com/intridea/grape-entity/pull/114): Added 'only' option that selects which attributes should be returned - [@estevaoam](https://github.com/estevaoam).
+* [#115](https://github.com/intridea/grape-entity/pull/115): Allowing 'root' to be inherited from parent to child entities - [@guidoprincess](https://github.com/guidoprincess).
 * Your contribution here.
 
 0.4.5 (2015-03-10)

lib/grape_entity/entity.rb

@@ -407,11 +407,11 @@ def self.present_collection(present_collection = false, collection_name = :items
     # @option options :only [Array] all the fields that should be returned
     def self.represent(objects, options = {})
       if objects.respond_to?(:to_ary) && ! @present_collection
-        root_element =  @collection_root
+        root_element =  root_element(:collection_root)
         inner = objects.to_ary.map { |object| new(object, { collection: true }.merge(options)).presented }
       else
         objects = { @collection_name => objects } if @present_collection
-        root_element =  @root
+        root_element = root_element(:root)
         inner = new(objects, options).presented
       end
 
@@ -420,6 +420,16 @@ def self.represent(objects, options = {})
       root_element ? { root_element => inner } : inner
     end
 
+    # This method returns the entity's root or collection root node, or its parent's
+    # @param root_type: either :collection_root or just :root
+    def self.root_element(root_type)
+      if instance_variable_get("@#{root_type}")
+        instance_variable_get("@#{root_type}")
+      elsif superclass.respond_to? :root_element
+        superclass.root_element(root_type)
+      end
+    end
+
     def presented
       if options[:serializable]
         serializable_hash

spec/grape_entity/entity_spec.rb

@@ -664,6 +664,30 @@ class Parent < Person
           end
         end
       end
+
+      context 'inheriting from parent entity' do
+        before(:each) do
+          subject.root 'things', 'thing'
+        end
+
+        it 'inherits single root' do
+          child_class = Class.new(subject)
+          representation = child_class.represent(Object.new)
+          expect(representation).to be_kind_of Hash
+          expect(representation).to have_key 'thing'
+          expect(representation['thing']).to be_kind_of(child_class)
+        end
+
+        it 'inherits array root root' do
+          child_class = Class.new(subject)
+          representation = child_class.represent(4.times.map { Object.new })
+          expect(representation).to be_kind_of Hash
+          expect(representation).to have_key('things')
+          expect(representation['things']).to be_kind_of Array
+          expect(representation['things'].size).to eq 4
+          expect(representation['things'].reject { |r| r.is_a?(child_class) }).to be_empty
+        end
+      end
     end
 
     describe '#initialize' do