Prevent infinite include loops in JsonApi + improve perfs.

Author: beauby

lib/active_model/serializer/adapter/json_api.rb

@@ -120,33 +120,33 @@ def relationships_for(serializer)
         end
 
         def included_for(serializer)
-          included_associations = serializer.expand_includes(@included)
-          included = included_associations.flat_map do |association, assoc_includes|
-            _included_for(association.serializer, assoc_includes)
+          included = []
+          included_associations = expand_includes(@included, serializer.associations)
+          included_associations.each do |association, assoc_includes|
+            _included_for(included, association.serializer, assoc_includes)
           end
 
-          included.uniq
+          included
         end
 
-        def _included_for(serializer, includes)
+        def _included_for(included, serializer, includes)
           if serializer.respond_to?(:each)
-            serializer.flat_map { |s| _included_for(s, includes) }.uniq
+            serializer.each { |s| _included_for(included, s, includes) }
           else
-            return [] unless serializer && serializer.object
+            return unless serializer && serializer.object
 
             primary_data = primary_data_for(serializer, @options)
             relationships = relationships_for(serializer)
             primary_data[:relationships] = relationships if relationships.any?
 
-            included = [primary_data]
+            return if included.include?(primary_data)
+
+            included.push(primary_data)
 
             included_associations = serializer.expand_includes(includes)
             included_associations.each do |association, assoc_includes|
-              included.concat(_included_for(association.serializer, assoc_includes))
-              included.uniq!
+              _included_for(included, association.serializer, assoc_includes)
             end
-
-            included
           end
         end