ProductDaoImpl

@Component
public class ProductDaoImpl implements ProductDao {

    @PersistenceContext(type = PersistenceContextType.EXTENDED)
    private EntityManager entityManager;

    public Product findById(Long id) {
        return entityManager.find(Product.class, id);
    }

    @Transactional
    public Product update(Product product, String updatedBrandName) {
        product.setBrand(updatedBrandName);
        entityManager.persist(product);
        return product;
    }

    public Product update(Long id, String updatedBrandName) {
        return this.update(this.findById(id), updatedBrandName);
    }
}