Hi Maddy, I wonder how an public CustomerDTO updateCustomer(CustomerDTO customerDTO) would be implemented by you? My straight forward solution would be: public CustomerDTO updateCustomer(CustomerDTO customerDTO) { Customer customer = customerRepository.getReferenceById(customerDTO.getId()); customer.setFirstName(customerDTO.getFirstName()); customer.setLastName(customerDTO.getLastName()); // ... repeated for all fields customerRepository.save(customer); } Note: The CustomerDTO requires some kind of resource identifier. I used the primary key of the database table.