increment_counter

# File activerecord/lib/active_record/associations/belongs_to_association.rb, line 68
        def increment_counter(counter_cache_name)
          if foreign_key_present?
            klass.increment_counter(counter_cache_name, target_id)
            if target && !stale_target?
              target.increment(counter_cache_name)
            end
          end
        end