public function form_validation() { global $database; $valid = new FormValidation(); $valid->validate_presences(self::$required_fields); if (!isset($this->id)) { $valid->unique_category(); } // $sql="SELECT * FROM" . " ".self::$table_name."WHERE category "; // $find_unique=$this->find_by_sql(); $valid->is_numeric('unit_price', ['min' => 0]); return $valid; }