Spring Boot include ID field in json

Question

I'm using spring-boot-starter-web and I want to use sideNumber of the bus as the Id value and return this value in a JSON repsonse.

Probably it's very simple but everything I found is related to Spring Data Rest.

Here is my entity clas:

@Entity
@Table(name = "buses")
class Bus(
        @Id
        @JsonProperty("sideNumber")
        @JsonInclude
        private val sideNumber: Int,
        @NotBlank
        var longitude: Double,
        @NotBlank
        var latitude: Double
)

I tried to annotate the sideNumber(Id) property with @JsonInclude and @Jsonproperty but with no luck. In my JSON response I only get longitude and latitude.

My controller looks like this:

@RestController
@RequestMapping("/api")
class BusController {

@Autowired
private lateinit var busRepository: BusRepository

@GetMapping("/buses")
fun getAllBuses(): List<Bus> {
    return busRepository.findAll()
}

@PostMapping("/buses")
fun createBus(@Valid @RequestBody bus: Bus): Bus {
    return busRepository.save(bus)
}

@GetMapping("/buses/{sideNumber}")
fun getBusById(@PathVariable(value = "sideNumber") sideNumber: Long): Bus {
    return busRepository.findById(sideNumber)
            .orElseThrow { ResourceNotFoundException("Bus", "sideNumber", sideNumber) }
}

@PutMapping("/buses/{sideNumber}")
fun updateBus(@PathVariable(value = "sideNumber") sideNumber: Long,
               @Valid @RequestBody newBus: Bus): Bus {

    val bus = busRepository.findById(sideNumber)
            .orElseThrow { ResourceNotFoundException("Bus", "sideNumber", sideNumber) }

    bus.latitude = newBus.latitude
    bus.longitude = newBus.longitude

    return busRepository.save(bus)
}

@DeleteMapping("/buses/{sideNumber}")
fun deleteBus(@PathVariable(value = "sideNumber") sideNumber: Long): ResponseEntity<*> {
    val bus = busRepository.findById(sideNumber)
            .orElseThrow { ResourceNotFoundException("Bus", "sideNumber", sideNumber) }

    busRepository.delete(bus)

    return ResponseEntity.ok().build<Any>()
}
}

What do I have to do to include this sideNumber(id) property into the JSON response?

Answer 1

By declaring a member property private you're telling Kotlin not to generate a getter for it.
Jackson, which is used by SpringBoot, uses getters to serialize objects.
That's the reason it doesn't see your property. And if it doesn't see the property, it doesn't get annotation either.
Easiest way to solve it would be to leave it as a val , but make it not private: val sideNumber: Int

More complicated way would be to create a @Bean of type ObjectMapper and configure Jackson to serialize also private members, as described here: https://docs.spring.io/spring-boot/docs/current/reference/html/howto-spring-mvc.html#howto-customize-the-jackson-objectmapper

Answer 2

I hope you must be extending RepositoryRestConfigurerAdapter and overrding configureRepositoryRestConfiguration method. If yes then Set the entity class names in exposeIdsFor() method. This will add display the id column in json.