如何使用jsp视图检查某个用户是否已创建数据库项

Question

I have a database table called bookings, and what i'm trying to do but couldn't find so far, is to check with if-else, if there are bookings made by certain user, and display them in a table.

So i'm looking for something like this:

(semi-pseudo code below)

<c:when test="${bookings.where(booking.userId == currentUserId) > 0}">
   display table with those items...
</c:when>

so this would get me all the table items made by that user

How can i test this in a jsp view page?

Thanks in advance.

PS: displaying the items is not a problem, i can at least do that on my own :)

EDIT backend part :

@GetMapping("/bookings")
    public String getAllBookings(Model model) {

        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
        UserDetails userDetail = (UserDetails) auth.getPrincipal();

        User user = userService.findByUsername(userDetail.getUsername());
        int currentUserId = user.getId();

        List<Booking> bookings = bookingService.getAllBookings();
        model.addAttribute("bookings", bookings);

        model.addAttribute("currentUserId", currentUserId);
        model.addAttribute("currentUser", getPrincipal());

        return "booking-list";
    }

Answer 1

First of all you probably should do this on backend and just pass filtered list, but for the jsp approach you can use forEach .

Example:

<c:forEach items="${bookings}" var="booking">
    <c:if test="${booking.userId == currentUserId}">
       ...
    </c:if>
</c:forEach>

Edit: question updated

To filter bookings in the backend you could use Stream API :

List<Booking> bookings = bookingService.getAllBookings().stream()
        .filter(b -> b.getUserId() == currentUserId)
        .collect(Collectors.toList());
model.addAttribute("bookings", bookings);

Edit 2.0:

Actually you shouldn't even filter them in java. Since you take the data from database, you should implement getBookingsForUserId() and use WHERE clause to filter them.