def cache_key
      if new_record?
        "#{model_name.cache_key}/new"
      else
        if cache_version
          "#{model_name.cache_key}/#{id}"
        else
          timestamp = max_updated_column_timestamp

          if timestamp
            timestamp = timestamp.utc.to_s(cache_timestamp_format)
            "#{model_name.cache_key}/#{id}-#{timestamp}"
          else
            "#{model_name.cache_key}/#{id}"
          end
        end
      end
    end
def cache_key
      if new_record?
        "#{model_name.cache_key}/new"
      else
        if cache_version
          "#{model_name.cache_key}/#{id}"
        else
          timestamp = max_updated_column_timestamp

          if timestamp
            timestamp = timestamp.utc.to_s(cache_timestamp_format)
            "#{model_name.cache_key}/#{id}-#{timestamp}"
          else
            "#{model_name.cache_key}/#{id}"
          end
        end
      end
    end
Returns a stable cache key that can be used to identify this record.

   Product.new.cache_key     # => "products/new"
   Product.find(5).cache_key # => "products/5"

 If ActiveRecord::Base.cache_versioning is turned off, as it was in Rails 5.1 and earlier,
 the cache key will also include a version.

   Product.cache_versioning = false
   Product.find(5).cache_key  # => "products/5-20071224150000" (updated_at available)