The Right Why Database Seeder with kotlin x spring boot - spring-boot

Question

today I'm learning build API using kotlin and spring boot. In rails and laravel have a "tool" for database seeder, I want to know in kotlin and spring boot, I have been searched on google before and found this answer https://stackoverflow.com/a/45324578/1297435, in spring boot we can use #EventListerner like
#EventListener
public void userSeeder(ContextRefreshedEvent event) {
// my query
// check query size and iteration
}
That's in spring boot, but is there a way in kotlin?
// main/kotlin/com.myapp.api/seeder/UserSeeder.kt
package com.myapp.api.seeder
import org.springframework.context.event.ContextRefreshedEvent
import com.myapp.api.repository.*
import com.myapp.api.model.*
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.stereotype.Component
interface EventListener
#Component
class UserSeeder {
#Autowired
lateinit var repository: UserRepository
#EventListener
fun seedUsername(event: ContextRefreshedEvent) {
val users = repository.findByUsernameBlank()
if (users == null || users!!.size <= 0) {
//
} else {
//
}
}
}
#EventListener class doesn't work in kotlin or is it correct?
Error:(15, 6) Kotlin: This class does not have a constructor

Answer 1

You probably have an issue because you define EventListener as an interface instead of importing it from org.springframework.context.event. (See interface EventListener just below the imports.
But you your actual question: I typically use org.springframework.boot.ApplicationRunner for such tasks.
import org.springframework.boot.ApplicationArguments
import org.springframework.boot.ApplicationRunner
#Component
class UserSeeder(private val repository: UserRepository) : ApplicationRunner {
override fun run(args: ApplicationArguments) {
val users = repository.findByUsernameBlank()
if (users == null || users!!.size <= 0) {
//
} else {
//
}
}
}
BTW: I also used constructor based injection.