Predefined objectsā methods are functionalities which are already defined and you can use it directly. It prevents from DRY, which means Don't Repeat Yourself. Donāt write code unless you have to. Write code only what you need, if you missed these predefined objectsā methods then you may repeat codes. You can find predefined objectsā methods at system/library Opencart has many predefined objectsā methods that can be called in Controller and Model. Like in admin section we can see predefined objects like: config, log, event, load, request, response, db, session, cache, url, langauge, openbay, document, customer, currency, tax, weight, length, cart, encryption, model_setting_event, user. Database Object of Opencart is $this->db Methods are: $this->db->escape($value) - mysql_real_escape_string() on the value passed $this->db->countAffected() - rows affected by an UPDATE query $this->db->getLastId() - last auto increment id same as mysql_i...