fixes a bug introduced by ruby-grape#203 where entities that expose attributes returned by a block (therefore absent from the object) would not be serialized

Author: Pedro Padron

lib/grape/entity.rb

@@ -259,7 +259,7 @@ def serializable_hash(runtime_options = {})
       return nil if object.nil?
       opts = options.merge(runtime_options || {})
       exposures.inject({}) do |output, (attribute, exposure_options)|
-        if object.respond_to?(attribute) && conditions_met?(exposure_options, opts)
+        if exposure_options.has_key?(:proc) || object.respond_to?(attribute) && conditions_met?(exposure_options, opts)
           partial_output = value_for(attribute, opts)
           output[key_for(attribute)] =
             if partial_output.respond_to? :serializable_hash

spec/grape/entity_spec.rb

@@ -252,6 +252,9 @@
     subject{ fresh_class.new(model) }
 
     describe '#serializable_hash' do
+
+
+
       it 'should not throw an exception if a nil options object is passed' do
         expect{ fresh_class.new(model).serializable_hash(nil) }.not_to raise_error
       end
@@ -285,6 +288,14 @@
         res.should_not have_key :non_existant_attribute
         res.should_not have_key :non_existant_attribute2
       end
+
+      it "should expose attributes that don't exist on the object only when they are generated by a block" do
+        fresh_class.expose :non_existant_attribute do |model, options|
+          "well, I do exist after all"
+        end
+        res = fresh_class.new(model).serializable_hash
+        res.should have_key :non_existant_attribute
+      end
 
       context "#serializable_hash" do