[FIXED] Kotlin & Spring Boot @ConfigurationProperties

Issue

How to properly initialize ConfigurationProperties in Spring Boot with Kotlin?

Currently I do like in the example below:

 @ConfigurationProperties("app")
 class Config {
     var foo: String? = null
 }

But it looks pretty ugly and actually foo is not a variable, foo is constant value and should be initialized during startup and will not change in the future.

Solution

With new Spring Boot 2.2 you can do like so:

@ConstructorBinding
@ConfigurationProperties(prefix = "swagger")
data class SwaggerProp(
    val title: String, val description: String, val version: String
)

And don't forget to include this in your dependencies in build.gradle.kts:

dependencies {
  annotationProcessor("org.springframework.boot:spring-boot-configuration-processor")
}

Answered By - Dmitry Kaltovich
Answer Checked By - Senaida (JavaFixing Volunteer)