Is there a more succinct way to initialize properties of a configuration from a properties file than...

# spring

[Hullaballoonatic]

Is there a more succinct way to initialize properties of a configuration from a properties file than this?

@Configuration
class FooConfiguration {
    @Value("\${foo.bar}")
    lateinit var bar: String
}

This just seems really verbose, even compared to the java way, and I tend to prefer lazy delegation val over lateinit var for immutable properties like this.

[Dariusz Kuc]

starting with SpringBoot 2.2

@ConstructorBinding
@Configuration("foo")
class FooConfiguration(val bar: String)

[Hullaballoonatic]

try as i might, i just cannot get this to work... a shame as that syntax is so much better

[Dariusz Kuc]

do you also have

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <version>${spring-boot.version}</version>
            <optional>true</optional>
        </dependency>

in your deps?

[Hullaballoonatic]

i'm using gradle:

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    val kotlinVersion = "1.3.50"
    idea
    kotlin("jvm") version kotlinVersion
    kotlin("plugin.spring") version kotlinVersion
    kotlin("kapt") version kotlinVersion
    id("org.springframework.boot") version "2.2.0.RELEASE"
    id("io.spring.dependency-management") version "1.0.8.RELEASE"
}

group = "org.example"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

dependencies {
    implementation(kotlin("stdlib-jdk8"))
    implementation(kotlin("reflect"))
    kapt("org.springframework.boot", "spring-boot-configuration-processor")
    implementation("org.springframework.boot", "spring-boot-configuration-processor")
    implementation("org.springframework.boot", "spring-boot-starter-web")
    implementation("org.springframework.security.oauth.boot", "spring-security-oauth2-autoconfigure", "2.2.0.RELEASE")
    implementation("org.springframework.boot", "spring-boot-starter-data-mongodb")
}

tasks.withType<KotlinCompile> {
    kotlinOptions.jvmTarget = "1.8"
}

[Hullaballoonatic]

so yes, and using kapt

[Dariusz Kuc]

it should work -> https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.2-Release-Notes#immutable-configurationproperties-binding

[Dariusz Kuc]

I've updated our lib recently -> https://github.com/ExpediaGroup/graphql-kotlin/pull/445

[Hullaballoonatic]

reading

[Hullaballoonatic]

I get

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'resource-server': @EnableConfigurationProperties or @ConfigurationPropertiesScan must be used to add @ConstructorBinding type src.config.ResourceServerConfiguration

when @EnableConfigurationProperties is literally right there in the code:

@EnableResourceServer
@EnableConfigurationProperties
@ConstructorBinding
@Configuration("resource-server")
class ResourceServerConfiguration(val resourceId: String) : ResourceServerConfigurerAdapter()

[Dariusz Kuc]

have you tried @EnableConfigurationProperties(FooConfiguration::class)?

[Dariusz Kuc]

thats how we got it configured

[Dariusz Kuc]

ah shouldnt @EnableConfigurationProperties be on other @Configuration class?

[Hullaballoonatic]

tried moving the annotation everywhere. i don't get this issue when i use the lateinit var syntax

[Hullaballoonatic]

it might be an intellij thing

[Dariusz Kuc]

no idea, @ConstructorBinding is new thing so maybe it is pretty finicky 🤷

[Hullaballoonatic]

durn. alright. nbd. hopefully 2.2.1 will fix the issue 😛

[jtravis]

I also tried & failed to get it to work.

[Hullaballoonatic]

I got it to work using

@ConstructorBinding
@ConfigurationProperties("foo")
class FooConfiguration(val bar: String)

[Hullaballoonatic]

@Dariusz Kuc

[Dariusz Kuc]

👍

[Hullaballoonatic]

I think it could be improved by interpreting the property name from the class name just as it does from the names of the class fields.

Also, then potentially the @ConfigurationProperties annotation would be superfluous and it could simply read:

@ConstructorBinding data class Foo(val bar: String, val baz: String)

[Dariusz Kuc]

it actually originally (in RCs) didn't need extra @ConstructorBinding annotation 🙂 unsure why pivotal decided to add that requirement in

[Hullaballoonatic]

yeah i could see how simply using the @configuration annotation should be able to realize which constructor arguments are autowired, and which are properties by checking the former then the latter

[Hullaballoonatic]

or having plugins or something like lombok so that you don't even have to redeclare the properties in your code. you can access them automatically if they're in the application.properties/yml file under the right property name

[Hullaballoonatic]

even though this is perfectly fine and working code, in intellij @ConfigurationProperties is highlighted as an error saying that this class is not designated as a component. if I add that annotation, everything still works fine, but then id is highlighted as an error saying there are no String beans. Calling wolf here is part of the reason I had such a hard time with it.

[Hullaballoonatic]

@EnableResourceServer
@ConstructorBinding
@ConfigurationProperties("resource-server")
class ResourceServerConfiguration(private val id: String) : ResourceServerConfigurerAdapter()

[Hullaballoonatic]

Also the "Re-run Spring Boot Annotation Processor to update generated metadata" banner message is annoying and should be addressed.