Merge pull request #97 from twinturbo/include-bug

Include Related Bugs

lib/active_model/serializer.rb

@@ -108,6 +108,18 @@ module ActiveModel
   #     end
   #
   class Serializer
+    class IncludeError < StandardError
+      attr_reader :source, :association
+
+      def initialize(source, association)
+        @source, @association = source, association
+      end
+
+      def to_s
+        "Cannot serialize #{association} when #{source} does not have a root!"
+      end
+    end
+
     module Associations #:nodoc:
       class Config #:nodoc:
         class_attribute :options
@@ -182,6 +194,10 @@ module ActiveModel
           option(:include, source_serializer._root_embed)
         end
 
+        def embeddable?
+          !associated_object.nil?
+        end
+
       protected
 
         def find_serializable(object)
@@ -216,6 +232,14 @@ module ActiveModel
       end
 
       class HasOne < Config #:nodoc:
+        def embeddable?
+          if polymorphic? && associated_object.nil?
+            false
+          else
+            true
+          end
+        end
+
         def polymorphic?
           option :polymorphic
         end
@@ -502,7 +526,9 @@ module ActiveModel
       if association.embed_ids?
         node[association.key] = association.serialize_ids
 
-        if association.embed_in_root?
+        if association.embed_in_root? && hash.nil?
+          raise IncludeError.new(self.class, association.name)
+        elsif association.embed_in_root? && association.embeddable?
           merge_association hash, association.root, association.serialize_many, unique_values
         end
       elsif association.embed_objects?