✅ How to get ticket sales
ticket sales= (total seats - remaining seats)/total seats * 100 remaining seats: schedule table에 있음 total seats of a cinema: cinema type table에 있음 한 영화에 대한 모든 schedule, 즉 schedule List가 주어짐
🟢 caculate total seats
schedule List에 있는 각각의 schedule에 대해 cinema type을 찾아서
cinema type table에 있는 total seats구하고 모두 더한다.
1
2
3
4
5
6
7
8
| private int caculateTotalSeats(List<Schedule> scheduleList){
//get total seats per cinema
int totalSeats= scheduleList.stream()
.map(schedule -> schedule.getCinemaType().getTotalSeats())
.mapToInt(Integer::intValue)
.sum();
return totalSeats;
}
|
🟢 caculate ticket sales
이제 remaining seats를 구해야 한다.
두 가지 방법이 있겠으나..
첫 번째 방법이 더 효율적이지만
두 번째 방법도 각각의 RemainingSeats에 대해 무언가를 해줄 수 있다는 점에서 알아두는데 의의가 있다.
👍🏻 방법 1. mapToInt().sum()
1
2
3
4
| int totalRemainingSeats= scheduleList.stream()
.map(Schedule::getRemainingSeats)
.mapToInt(Integer::intValue)
.sum();
|
👍🏻 방법 2. RemainingSeats를 구해 List로 만들고, List를 돌면서 더한다.
1
2
3
4
| List<Integer> remainingSeatsList= scheduleList.stream().map(Schedule::getRemainingSeats).toList();
int totalRemainingSeats= 0;
for(int x: remainingSeatsList) totalRemainingSeats +=x;
int totalSeats= caculateTotalSeats(scheduleList);
|
☑️ 이제 마지막으로, ticket sales를 계산한다.
1
2
3
4
| double ticketSales = ((double) (totalSeats - totalRemainingSeats)totalSeats * 100.0) ;
//show only until 소수점 첫째자리
double formattedTicketSales= Math.round(ticketSales*10.0)/10.0;
return formattedTicketSales;
|
🟢 Final Code
여러번 사용해서 다른 메소드에서 구현
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
| private double caculateTicketSales(List<Schedule> scheduleList){
//remaining seats(schedule) / total seats(cinema type) * 100
//1. get List<schedule> to get remaining seats
//2. for each schedule in list, get total seats from cinema type
//3. do the math
List<Integer> remainingSeatsList= scheduleList.stream().map(Schedule::getRemainingSeats).toList();
int totalRemainingSeats= 0;
for(int x: remainingSeatsList) totalRemainingSeats +=x;
int totalSeats= caculateTotalSeats(scheduleList);
double ticketSales = ((double) (totalSeats - totalRemainingSeats) /totalSeats * 100.0) ;
//show only until 소수점 첫째자리
double formattedTicketSales= Math.round(ticketSales*10.0)/10.0;
return formattedTicketSales;
}
private int caculateTotalSeats(List<Schedule> scheduleList){
//get total seats per cinema
int totalSeats= scheduleList.stream()
.map(schedule -> schedule.getCinemaType().getTotalSeats())
.mapToInt(Integer::intValue)
.sum();
return totalSeats;
}
|
🟢 Cleaner Code
💡 .mapToInt(Integer::intValue)를 안하면 sum()안 됨!!
💡 나누는 수가 0이 되지 않도록 주의하자.
if (totalSeats == 0) throw new NotFoundException 해서 예외 처리하기
🔴 double ticketSales= 를 구하는 식에서 계속 에러가 났다. ticketSales가 계속 0이 뜨는 것이다.
그 이유는 나누어지는 수가 먼저 (double)처리가 되어야 하기 떄문이었다.
❌ double ticketSales= (double)((totalSeats- remainingSeats)/totalSeats)*100;
⭕️ double ticketSales= ((double) (totalSeats- remainingSeats)/totalSeats)*100;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
| Page<Movie> moviePage= movieJpa.findAll(pageable);
for(Movie movie: moviePage){
//ticketSales
List<Schedule> scheduleList= movie.getScheduleList();
int remainingSeats= scheduleList.stream().mapToInt(Schedule::getRemainingSeats).sum();
int totalSeats= scheduleList.stream().map(Schedule::getCinemaType).map(CinemaType::getTotalSeats).mapToInt(Integer::intValue).sum();
if (totalSeats == 0) throw new NotFoundException("There are no total seats for this movie");
//same code
// int toalSeats= scheduleList.stream().map(schedule -> schedule.getCinemaType().getTotalSeat()).mapToInt(Integer::intValue).sum();
double ticketSales= ((double) (totalSeats- remainingSeats)/totalSeats)*100;
double formattedTicketSales= (double) Math.round(ticketSales*10.0)/10.0;
movie.setTicketSales(formattedTicketSales);
movieJpa.save(movie);
}
|
🟢 JPA에서 구하는 방법
movie table에 ticket_sales라는 field가 있음
따라서 ticket_sales를 구해서 movie table에 넣어주는(update해주는) JPQL
1
2
3
4
5
6
7
8
9
10
11
12
| @Repository
public interface MovieJpa extends JpaRepository<Movie, Integer> {
@Transactional
@Modifying
@Query(
value = "UPDATE movie AS A " +
"INNER JOIN schedule AS B ON A.movie_id = B.movie_id " +
"INNER JOIN cinema_type AS C ON B.cinema_type_id = C.cinema_type_id " +
"SET A.ticket_sales = (1 - (B.remaining_seats / C.total_seats)) * 100 "
, nativeQuery = true)
void updateTicketSales();
}
|