Vlad

While this may be obvious, but the serialize method can take 2 types of argument - a class (like Array) or a coder (as coder: CoderClass).

For a custom class coder option is necessary. Additionally, the coder Class needs to be added to Rails.application.config.active_record.yaml_column_permitted_classes during the initialization, unless Rails.application.config.active_record.use_yaml_unsafe_load is used (which is not ideal.)