airframe-config: Support loading JavaBean?

[wvlet]

airframe-config: Support loading JavaBean?

[xerial]

Could you give me more context?

[0x1997]

val config = Config(env = configEnv, configPaths = Seq(configPath))
      .registerFromYaml[FooConfig]("foo.yml")

This doesn't work when FooConfig is a JavaBean instead of a scala case class.
My workaround is like this

import java.io.{File, FileNotFoundException}

import scala.collection.JavaConverters._
import scala.reflect.runtime.universe._

import org.yaml.snakeyaml.{TypeDescription, Yaml}
import org.yaml.snakeyaml.constructor.Constructor
import wvlet.config.Config
import wvlet.log.LogSupport
import wvlet.log.io.IOUtil.readAsString
import wvlet.surface

object Yaml2JavaBean {
  implicit class ConfigWithJavaBeanSupport(config: Config) extends LogSupport {
    def registerJavaBeanFromYaml[T: TypeTag](yamlFile: String): Config = {
      val env = config.env
      val tpe = surface.of[T]
      val realPath = env.configPaths
        .map(p => new File(p, yamlFile))
        .find(_.exists())
        .map(_.getPath)
        .getOrElse {
          throw new FileNotFoundException(
            s"$yamlFile is not found in ${env.configPaths.mkString(":")}")
        }
      val constructor = new Constructor()
      constructor.addTypeDescription(
        new TypeDescription(
          typeTag[T].mirror.runtimeClass(typeOf[T].typeSymbol.asClass),
          "!bean"))
      val yaml = new Yaml(constructor)
      val m = yaml
        .loadAs(readAsString(realPath), classOf[java.util.Map[String, T]])
        .asScala

      val conf = m.get(env.env) match {
        case Some(x) =>
          info(s"Loading $tpe from $realPath, env:${env.env}")
          x
        case None =>
          // Load default
          debug(
            s"Configuration for ${env.env} is not found in $realPath. Load ${env.defaultEnv} configuration instead")
          m.get(env.defaultEnv) map { x =>
            info(s"Loading $tpe from $realPath, default env:${env.defaultEnv}")
            x
          } getOrElse {
            throw new IllegalArgumentException(
              s"No configuration for $tpe (${env.env} or ${env.defaultEnv}) is found")
          }
      }

      config.register[T](conf)
    }
  }
}

import Yaml2JavaBean._

val config = Config(env = configEnv, configPaths = Seq(configPath))
      .registerJavaBeanFromYaml[FooConfig]("foo.yml")

where foo.yml is like this

default: !bean
  application:
    name: foo-service
  registry:
    protocol: zookeeper
    address: 10.10.0.1:2181,10.10.0.2:2182,10.10.0.3:2183
  id: fooService
  interface: com.foo.service.FooService
  version: 1.0.0
  timeout: 100

[xerial]

In #110, I've changed how to map Yaml -> Objects. Yaml data is converted to MessagePack binary data, and it is read in ObjectCodec (airframe-tablet). By adding MsgPack -> JavaBeans codec, it would be possible to support this type of binding in a more generic manner.

Alternatively simply adding your workaround to airframe-config might be convenient for you.

[xerial]

Using mutable JavaBeans is not a good practice in Scala. I think we will not address this.