Correctly serializes nested hash elements when a root element is used with an Entity.

Previously, when a root element is used with an Entity, the presenter
wraps the array of Entity object in a plain hash, and the Entities end
up serialized as plain strings of the class name
(i.e., {"root":["#<EntityFoo...>","#<EntityBar...>"])

The new code recursively checks for any elements of the hash that respond
to serializable_hash and calls it if present.

Author: Ben Rosenblum

lib/grape/middleware/base.rb

@@ -110,17 +110,26 @@ def decode_json(object)
           MultiJson.load(object)
         end
 
+        def serialize_recurse(object)
+          if object.respond_to? :serializable_hash
+            object.serializable_hash
+          elsif object.kind_of?(Array) && !object.map {|o| o.respond_to? :serializable_hash }.include?(false)
+            object.map {|o| o.serializable_hash }
+          elsif object.kind_of?(Hash)
+            object.inject({}) { |h,(k,v)| h[k] = serialize_recurse(v); h }
+          else
+            object
+          end
+        end
+
         def encode_json(object)
           return object if object.is_a?(String)
 
-          if object.respond_to? :serializable_hash
-            MultiJson.dump(object.serializable_hash)
-          elsif object.kind_of?(Array) && !object.map {|o| o.respond_to? :serializable_hash }.include?(false)
-            MultiJson.dump(object.map {|o| o.serializable_hash })
-          elsif object.respond_to? :to_json
+          serialized_hash = serialize_recurse(object)
+          if (object == serialized_hash) && (object.respond_to? :to_json)
             object.to_json
           else
-            MultiJson.dump(object)
+            MultiJson.dump(serialized_hash)
           end
         end
 

spec/grape/middleware/formatter_spec.rb

@@ -48,6 +48,18 @@ def serializable_hash
       subject.call({'PATH_INFO' => '/somewhere', 'HTTP_ACCEPT' => 'application/json'}).last.each{|b| b.should == '{"abc":"def"}'}
     end
 
+    it 'should serialize objects that respond to #serializable_hash if there is a root element' do
+      class SimpleExample
+        def serializable_hash
+          {:abc => 'def'}
+        end
+      end
+
+      @body = {"root" => SimpleExample.new}
+
+      subject.call({'PATH_INFO' => '/somewhere', 'HTTP_ACCEPT' => 'application/json'}).last.each{|b| b.should == '{"root":{"abc":"def"}}'}
+    end
+
     it 'should call #to_xml if the content type is xml' do
       @body = "string"
       @body.instance_eval do