lib/rails_erd/domain/relationship.rb in rails-erd-1.3.0 vs lib/rails_erd/domain/relationship.rb in rails-erd-1.3.1

@@ -188,10 +188,10 @@
       def any_habtm?(associations)
         associations.any? { |association| association.macro == :has_and_belongs_to_many }
       end
 
       def foreign_key_required?(association)
-        if association.belongs_to?
+        if !association.active_record.abstract_class? and association.belongs_to?
           column = association.active_record.columns_hash[association.send(Domain.foreign_key_method_name)] and !column.null
         end
       end
     end
   end