Convert Integer to JSON - spring

Question

I'm playing around in SpringBoot and i want to count the amount of users in my database.
UserRepository
public interface UserRepository extends JpaRepository<User, Long> {
#Query(value = "select COUNT(*) from user", nativeQuery = true)
Integer findAllActiveUsers();
}
UserService
public Integer amountOfUsersInDB() {
return userRepository.findAllActiveUsers();
}
UserController
#GetMapping("/myusers")
public ResponseEntity amountOfUsers() {
System.out.println(userService.amountOfUsersInDB());
return ResponseEntity.ok(userService.amountOfUsersInDB());
}
When i make the http get call it returns the amount of users inside my database as an Integer. How can i make it return the value as an JSON so i can later on dsplay it on my frontend?

Answer 1

When you have something like this:
#GetMapping(value = "/count", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Integer> getCount() {
Integer count = 1;
return ResponseEntity.ok(count);
}
You'll have the following response payload which, by the way, is a valid JSON:
1
Now, if you want to produce a JSON object, then you could use a Map<String, Object> for representing the payload:
#GetMapping(value = "/count", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Map<String, Object>> getCount() {
Integer count = 1;
Map<String, Object> payload = new HashMap<>();
payload.put("count", count);
return ResponseEntity.ok(payload);
}
Or you could define a class representing the payload, create and instance of such class and assign a value to the count field:
#Data
public class CountPayload {
private Integer count;
}
#GetMapping(value = "/count", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<CountPayload> getCount() {
Integer count = 1;
CountPayload payload = new CountPayload();
payload.setCount(count);
return ResponseEntity.ok(payload);
}