11. Build Update Employee REST API

EmployeeService

    EmployeeDto updateEmployee(EmployeeDto employeeDto);

EmployeeServiceImpl

    @Override
    public EmployeeDto updateEmployee(EmployeeDto employeeDto) {
        // we need to check whether employee with given id is exist in DB or not
        Employee existingEmployee = employeeRepository.findById(employeeDto.getId())
                .orElseThrow(() -> new IllegalArgumentException(
                        "Employee not exists with a given id : " + employeeDto.getId())
                );

        // convert EmployeeDto to Employee JPA entity
        Employee employee = EmployeeConverter.mapToEmployee(employeeDto);
        return EmployeeConverter.mapToEmployeeDto(employeeRepository.save(employee));
    }

EmployeeController

    // build update employee REST API
    // http://localhost:8080/api/employees/1
    @PutMapping("{id}")
    public ResponseEntity<EmployeeDto> updateEmployee(@PathVariable("id") long id
            ,@RequestBody EmployeeDto employeeDto){
        employeeDto.setId(id);
        EmployeeDto updatedEmployee = employeeService.updateEmployee(employeeDto);
        return new ResponseEntity<EmployeeDto>(updatedEmployee, HttpStatus.OK);
    }