|  |  | 
 |  |  |       $this->addStatement = $this->pdo->prepare('INSERT OR REPLACE INTO vehicles (id, num, weight) VALUES (?, ?, ?)'); | 
 |  |  |    } | 
 |  |  |     | 
 |  |  |    public function beginTransaction() { | 
 |  |  |       $this->pdo->beginTransaction(); | 
 |  |  |    } | 
 |  |  | 	 | 
 |  |  |    public function commit() { | 
 |  |  |       $this->pdo->commit(); | 
 |  |  |    } | 
 |  |  | 	 | 
 |  |  |    public function rollback() { | 
 |  |  |       $this->pdo->rollback(); | 
 |  |  |    } | 
 |  |  | 	 | 
 |  |  |    public function getById($id) { | 
 |  |  |       $this->getByIdStatement->execute([$id]); | 
 |  |  |       return $this->getByIdStatement->fetch(); | 
 |  |  | 
 |  |  |    } | 
 |  |  |     | 
 |  |  |    public function addMapping($mapping) { | 
 |  |  |       $this->beginTransaction(); | 
 |  |  |       $weight = count($mapping); | 
 |  |  |       foreach($mapping as $id => $vehicle) { | 
 |  |  |          $this->add($id, (int)substr($vehicle['num'], 2), $weight); | 
 |  |  |       } | 
 |  |  |       $this->commit(); | 
 |  |  |    } | 
 |  |  | } |