Using data class in micronaut properties - kotlin

Question

I'm writing configuration properties and would like to use data class to hold the data.
Problem is, data classes have a primary constructor and are immutable, and micronaut tries to inject the values as beans.
Example:
#ConfigurationProperties("gerencianet")
data class GerenciaNetConfiguration(
val clientId: String,
val clientSecret: String,
val apiUrl: String,
val notificationUrl: String,
val datePattern: String = "yyyy-MM-dd HH:mm:ss"
)
Error: Caused by: io.micronaut.context.exceptions.NoSuchBeanException: No bean of type [java.lang.String] exists. Make sure the bean is not disabled by bean requirements
Is there support for it?

Answer 1

You can inject the values as constructor parameters using #Parameter. It avoids common mistakes with #Value.
For example, if your application.yml looks like this:
group:
first-value: asdf
second-value: ghjk
Then a Kotlin class might look like:
import io.micronaut.context.annotation.Property
import javax.inject.Singleton
#Singleton
class MyClass(#Property(name = "group.first-value") val firstValue: String) {
fun doIt(): String {
return firstValue
}
}
Or, similarly, a method:
import io.micronaut.context.annotation.Factory
import io.micronaut.context.annotation.Property
import javax.inject.Singleton
#Factory
class MyFactory {
#Singleton
fun getSomeValue(#Property(name = "group.first-value") firstValue: String): SomeClass {
return SomeClass.newBuilder()
.setTheValue(firstValue)
.build()
}
}

Answer 2

One option you have is to do something like this:
import io.micronaut.context.annotation.ConfigurationBuilder
import io.micronaut.context.annotation.ConfigurationProperties
#ConfigurationProperties("my.engine")
internal class EngineConfig {
#ConfigurationBuilder(prefixes = ["with"])
val builder = EngineImpl.builder()
#ConfigurationBuilder(prefixes = ["with"], configurationPrefix = "crank-shaft") / <3>
val crankShaft = CrankShaft.builder()
#set:ConfigurationBuilder(prefixes = ["with"], configurationPrefix = "spark-plug")
var sparkPlug = SparkPlug.builder()
}
That is from our test suite at https://github.com/micronaut-projects/micronaut-core/blob/1c3e2c3280da200c96e629a4edb9df87875ef2ff/test-suite-kotlin/src/test/kotlin/io/micronaut/docs/config/builder/EngineConfig.kt.
You can also inject the values as constructor parameters using #Value.
I hope that helps.