Modify Spring data Page<> class projection response in service layer

Question

I am using projection, and I need to format the date variable in list of objects, but Page<> type response is read only, so I can not iterate and modify the objects. What Should I do?

@Override
public Page<OrderDto> findAll(Pageable pageable) {
    return OrderDao.findByIsEnabledTrue(pageable, OrderDto.class);
}

I tried like this:

@Override
public Page<OrderDto> findAll(Pageable pageable) {

    Page<OrderDto> page = orderDao.findByIsEnabledTrue(pageable, OrderDto.class);

    List<OrderDto> orderDtos = page.getContent();

    orderDtos.stream().forEach(it ->{
        it.setFormattedCreatedAt(new SimpleDateFormat("dd-M-yyyy").format(it.getCreatedAt()));
    });

    page.getContent().clear();
    page.getContent().addAll(orderDtos);

    return page;
}

Answer 1

page.getContent() returns an unmodifiable list. The best approach is to use map method provided by page:

@Override
public Page<OrderDto> findAll(Pageable pageable) {
  Page<OrderDto> page = orderDao.findByIsEnabledTrue(pageable, OrderDto.class);
  page = page.map(this :: transformOrderDto);
  return page;
}

private OrderDto transformOrderDto(final OrderDto order) {
  order. setFormattedCreatedAt(new SimpleDateFormat("dd-M-yyyy").format(order.getCreatedAt()));
  return order;
}