CityEntity.kt

@Entity
@Table(name="city")
internal data class CityEntity(
   @Id val id: Long? = null,
   val name: String,
   val description: String? = null) {

  fun toDto(): CityDto = CityDto(
    id = this.id!!,
    name = this.name,
    description = this.description)

  companion object {

    fun fromDto(dto: CityDto) = CityEntity(
      id = dto.id,
      name = dto.name,
      description = dto.description)

    fun fromDto(dto: CreateCityDto) = CityEntity(
      name = dto.name,
      description = dto.description)

    fun fromDto(dto: UpdateCityDto, defaultCity: CityEntity) = CityEntity(
                id = defaultCity.id!!,
                name = dto.name ?: defaultCity.name,
                description = dto.description ?: defaultCity.description)
  }
}