ConfigurationProperties loading list from YML - spring

Question

I'm trying to load Configuration from YML. I can load value and I can also load list if these are comma seperated values. But i can't load a typical YML List.
Configuration Class
#Component
#PropertySource("classpath:routing.yml")
#ConfigurationProperties
class RoutingProperties(){
var angular = listOf("nothing")
var value: String = ""
}
Working routing.yml
angular: /init, /home
value: Hello World
Not Working routing.yml
angular:
- init
- home
value: Hello World
Why can't i load the second version of yml / do I have a syntaxt error?
ENV: Kotlin, Spring 2.0.0.M3

Answer 1

As #flyx say, #PropetySource not worked with yaml files. But in spring you may override almost everything :)
PropertySource has additional parameter: factory. It's possible to create your own PropertySourceFactory base on DefaultPropertySourceFactory
open class YamlPropertyLoaderFactory : DefaultPropertySourceFactory() {
override fun createPropertySource(name: String?, resource: EncodedResource?): org.springframework.core.env.PropertySource<*> {
if (resource == null)
return super.createPropertySource(name, resource)
return YamlPropertySourceLoader().load(resource.resource.filename, resource.resource, null)
}
}
And when use this factory in propertysource annotation:
#PropertySource("classpath:/routing.yml", factory = YamlPropertyLoaderFactory::class)
Last that you need is to initialized variable angular with mutableList
Full code sample:
#Component
#PropertySource("classpath:/routing.yml", factory = YamlPropertyLoaderFactory::class)
#ConfigurationProperties
open class RoutingProperties {
var angular = mutableListOf("nothing")
var value: String = ""
override fun toString(): String {
return "RoutingProperties(angular=$angular, value='$value')"
}
}
open class YamlPropertyLoaderFactory : DefaultPropertySourceFactory() {
override fun createPropertySource(name: String?, resource: EncodedResource?): org.springframework.core.env.PropertySource<*> {
if (resource == null)
return super.createPropertySource(name, resource)
return YamlPropertySourceLoader().load(resource.resource.filename, resource.resource, null)
}
}
#SpringBootApplication
#EnableAutoConfiguration(exclude = arrayOf(DataSourceAutoConfiguration::class))
open class Application {
companion object {
#JvmStatic
fun main(args: Array<String>) {
val context = SpringApplication.run(Application::class.java, *args)
val bean = context.getBean(RoutingProperties::class.java)
println(bean)
}
}
}

Answer 2

Kinda old post, i know. But i am at the very same topic right now.
As of now, it seems that PropertySource does indeed work with yaml Files. Given the restriction that it only allows for primitive types (it seems) and it cant handle nested elements. I'm probably gonna dig a bit deeper and update my answer accordingly, but as of now, the accepted answer seems like a functioning workaround.

Answer 3

Well, according to the docs, your YAML file will be rewritten into a property file. The first YAML file becomes:
angular=/init, /home
value=Hello World
While the second one becomes:
angular[0]=init
angular[1]=home
value=Hello World
These are obviously two very different things and therefore behave differently.
Moreover, later in the docs, it is stated that YAML does not even work with #PropertySource:
24.6.4 YAML shortcomings
YAML files can’t be loaded via the #PropertySource annotation. So in the case that you need to load values that way, you need to use a properties file.
That makes me kind of wonder why the first case works for you at all.
The docs say this about the generated …[index] properties:
To bind to properties like that using the Spring DataBinder utilities (which is what #ConfigurationProperties does) you need to have a property in the target bean of type java.util.List (or Set) and you either need to provide a setter, or initialize it with a mutable value, e.g. this will bind to the properties above
So, let's have a look at Kotlin docs: listOf returns a new read-only list of given elements. So the list is not mutable as required by the docs, which I assume is why it doesn't work. Try using a mutable list (since I have never used Kotlin, I cannot give you working code). Also try to declare it as java.util.List if that's possible in Kotlin.