Fix json serialization of nested hash when using root elements with a Grape::Entity presenter

CHANGELOG.markdown

@@ -1,6 +1,7 @@
 Next Release
 ============
 
+* [#181](https://github.com/intridea/grape/pull/181): Fix: Corrected JSON serialization of nested hashes containing `Grape::Entity` instances - [@benrosenblum](https://github.com/benrosenblum).
 * [#64](https://github.com/intridea/grape/issues/64), [#180](https://github.com/intridea/grape/pull/180): Added support to get request bodies as parameters - [@bobbytables](https://github.com/bobbytables).
 * [#175](https://github.com/intridea/grape/pull/175): Added support for API versioning based on a request parameter - [@jackcasey](https://github.com/jackcasey).
 * [#168](https://github.com/intridea/grape/pull/168): Fix: Formatter can parse symbol keys in the headers hash - [@netmask](https://github.com/netmask).

lib/grape/entity.rb

@@ -232,7 +232,10 @@ def serializable_hash(runtime_options = {})
       return nil if object.nil?
       opts = options.merge(runtime_options || {})
       exposures.inject({}) do |output, (attribute, exposure_options)|
-        output[key_for(attribute)] = value_for(attribute, opts) if conditions_met?(exposure_options, opts)
+        partial_output = value_for(attribute, opts) if conditions_met?(exposure_options, opts)
+        partial_output = partial_output.serializable_hash(runtime_options) if partial_output.respond_to? :serializable_hash
+        output[key_for(attribute)] = partial_output
+
         output
       end
     end

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/entity_spec.rb

@@ -257,6 +257,28 @@
         fresh_class.expose :name
         expect{ fresh_class.new(nil).serializable_hash }.not_to raise_error
       end
+
+      it 'should serialize embedded objects which respond to #serializable_hash' do
+        class EmbeddedExample
+          def serializable_hash(opts = {})
+            {:abc => 'def'}
+          end
+        end
+
+        class SimpleExample
+          def name
+            "abc"
+          end
+
+          def embedded
+            EmbeddedExample.new
+          end
+        end
+
+        fresh_class.expose :name, :embedded
+        presenter = fresh_class.new(SimpleExample.new)
+        presenter.serializable_hash.should == {:name => "abc", :embedded => {:abc => "def"}}
+      end
     end
 
     describe '#value_for' do

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