No value passed for parameter - spring-boot

Question

I use kotli. I define everything as per requirement, why I am getting
thing type of Issue
UserRegistrationService.kt: (25, 36): No value passed for parameter 'userRegistration'
I got this type of issue at my UserRegistration class No value passed
for parameter department, and userRegistration
I Creat ResponseTemplateVO POJO Class
ResponseVO.kt
package com.userservice.userregistration.VO
import com.userservice.userregistration.entity.UserRegistration
data class ResponseTemplateVO(
var userRegistration: UserRegistration,
var department: Department
)
Department.kt
package com.userservice.userregistration.VO
data class Department(
val departmentId:Long=-1,
val departmentName:String="",
val departmentAddress:String="",
val departmentCode:String=""
)
UserRegistration.kt
package com.userservice.userregistration.entity
data class UserRegistration(
val userId:Long=-1,
val firstName:String="",
val lastName:String="",
val email:String="",
val departmentId:Long=-1,
)
UserRegistrationService.kt
package com.userservice.userregistration.service
import com.userservice.userregistration.VO.Department
import com.userservice.userregistration.VO.ResponseTemplateVO
import com.userservice.userregistration.entity.UserRegistration
import com.userservice.userregistration.repository.UserRegistrationRepository
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.stereotype.Service
import org.springframework.web.client.RestTemplate
#Service
class UserRegistrationService {
#Autowired
private lateinit var userRegistrationRepository: UserRegistrationRepository
#Autowired
private lateinit var restTemplate: RestTemplate
fun saveUserDetails(userRegistration: UserRegistration): UserRegistration {
return userRegistrationRepository.save(userRegistration)
}
fun getUserWithDepartment(userId: Long): ResponseTemplateVO {
val vo= ResponseTemplateVO()
val userRegistration:UserRegistration=userRegistrationRepository.findUserById(userId)
val department: Department? =
restTemplate.getForObject("http://localhost:9001/departments/"+userRegistration.departmentId,
Department::class.java)
vo.userRegistration=userRegistration
if (department != null) {
vo.department=department
}
return vo
}
}
I am getting error at this below method at the line 2
val vo= ResponseTemplateVO()
No value passed for parameter department and userRegistration .This is
the error
fun getUserWithDepartment(userId: Long): ResponseTemplateVO {
val vo= ResponseTemplateVO()
val userRegistration:UserRegistration=userRegistrationRepository.findUserById(userId)
val department: Department? =
restTemplate.getForObject("http://localhost:9001/departments/"+userRegistration.departmentId,
Department::class.java)
vo.userRegistration=userRegistration
if (department != null) {
vo.department=department
}
return vo
}

Answer 1

This declaration:
data class ResponseTemplateVO(
var userRegistration: UserRegistration,
var department: Department
)
packs multiple things:
it declares 2 properties userRegistration and department
it defines the primary constructor of the class with 2 arguments: userRegistration and department
When you write:
val vo = ResponseTemplateVO()
You're calling the constructor of that class, but you don't specify the 2 required arguments. You should instead call it by passing the arguments:
fun getUserWithDepartment(userId: Long): ResponseTemplateVO {
val userRegistration:UserRegistration=userRegistrationRepository.findUserById(userId)
val department: Department? = restTemplate.getForObject("http://localhost:9001/departments/"+userRegistration.departmentId,
Department::class.java)
if (department == null) {
// here you should decide if it should have a default value
// or throw an exception
}
return ResponseTemplateVO(userRegistration, department)
}
Note that you declared the department property as non-null, so you need a non-null department in order to create an instance of your class.
So if department is null you have 3 options:
throw an exception
use a default value instead
change the type of department in ResponseTemplateVO so it accepts nulls (Department? with ?)
Also, if you instantiate your class with all required value like that, and you don't need to modify its properties later, the properties can be declared val. This is usually more idiomatic Kotlin. With immutability, it's easier to reason about the values.

Answer 2

The issue is in the data class.
data class ResponseTemplateVO(
var userRegistration: UserRegistration,
var department: Department
)
Here you have added the following params into the constructor of the data class. Hence you will need to pass the values to the constructor of the class before you can initialise it.
Hence your ResponseTemplateVO data class will become like this
data class ResponseTemplateVO(
var userRegistration: UserRegistration?=null,
var department: Department?=null)
Now since we have already assigned null as the default value. Now you can initialise the data class and it creates the data class with the values set to null and you do not need to pass any value for params to the constructor. Now you can access each of the variables and set the respective data into them.