CODEWITHSUNDEEP
javalistconfigtypesafe
DHa
DHa

Reputation: 669

How to get a list of lists in Typesafe Config

I have a typesafe config with a list of lists. Basically what I'm trying to do is to extract a multi-map.

myconfig {
  values = [
      [ 'key1', 'value1'],
      [ 'key1', 'value2'],
      [ 'key2', 'value2'],
      [ 'key2', 'value3'],
    ]

Workaround I has to use:

myconfig {
  values = {
    key1 : [ 'value1' , 'value2' ]
    key2 : [ 'value2' , 'value3' ]
  }
}

Is there a nice way of extracting the original list of lists? All functions expect a path, so once I extract 'values' there seem to be no direct way of accessing an inner list.

Upvotes: 2

Views: 9723

Answers (1)

Quy
Quy

Reputation: 1373

You can use the getList(String path) on the Config object to get back a ConfigList object.

Java:

config.getList("path.to.keys").stream()
  .map(configValue -> (ArrayList) configValue.unwrapped())
  .collect(Collectors.toList())

A ConfigList contains ConfigValue instances. In this case, the typesafe people represent the list internally as an ArrayList so you have to make the cast when you unwrap the ConfigValue object.

The snippet above returns a List of List. If you want to flatten the list, use flatMap instead of Map and return a stream in the lambda.

Edit

Here's the equivalent Scala:

  import scala.collection.JavaConversions._
  val keys: Map[String, String] = config.getList("path.to.keys")
    .map(configValue =>
      configValue.unwrapped().asInstanceOf[ArrayList[String]]
    )
    .foldLeft(Map[String, String]())( (map, list) =>
      map + (list(0) -> list(1))
    )

Upvotes: 5

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