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Version: 2.0.x

Automatic Validations

By bringing in zio-config-refined module, you get validations for your config parameters almost for free. zio-config elegantly integrates with Refined library for you to achieve this with same ergonomics.

If you are not familiar with refined library, refer

There are various ways that zio-config can interact with refined library. Take a look at zio.config.refined package.

 import zio.Config
import zio.ConfigProvider
import zio.config._, refined._

A few examples are given below.

Basic Example

 import eu.timepit.refined.types.string.NonEmptyString

case class Jdbc(username: NonEmptyString, password: NonEmptyString)

val jdbc: Config[Jdbc] =
(refineType[NonEmptyString]("username") zip

ConfigProvider.fromMap(Map("username" -> "", "password" -> "")).load(jdbc)

Direct Interaction with Refined Predicates

If you need to directly interact with Predicates (ex: NonEmpty), then refine[A, P] method is useful.

 import eu.timepit.refined._, api._, string._, collection._

type NonEmptyString = String Refined NonEmpty

val refinedConfig: Config[NonEmptyString] =

// Another way of doing it is
val urlConfig: Config[Refined[String, Url]] =
refine[String, Url]("URL")

// refineType takes a fully formed type (String Refined NonEmpty) where as refine allows you to play with the predicate directly (NonEmpty)

Derive from existing Config

Of various methods available in zio.config.refined package, the most interesting one is being able to get a refined type out of an already derived Config. This shows the composable nature of zio-config.

Take a look at the below example

 import eu.timepit.refined._, api._, numeric._, collection._
import zio.config.magnolia.deriveConfig

case class MyConfig(url: String, port: Int)

val configs: Config[List[MyConfig]] =
Config.listOf("databases", deriveConfig[MyConfig])

// A list of database configs, such that size should be greater than 2.
val databaseList: Config[Refined[List[MyConfig], Size[Greater[W.`2`.T]]]] =

Auto-Derivation and Refined

You can also use auto derivations with refined.

import zio.ConfigProvider
import eu.timepit.refined.W
import eu.timepit.refined.api.Refined
import eu.timepit.refined.collection.{ NonEmpty, Size }
import zio.config.magnolia.deriveConfig

object RefinedReadConfig extends App {
case class RefinedProd(
ldap: Refined[String, NonEmpty],
port: Refined[Int, GreaterEqual[W.`1024`.T]],
dbUrl: Option[Refined[String, NonEmpty]]

val configMap =
"LDAP" -> "ldap",
"PORT" -> "1999",
"DBURL" -> "ddd"

val result =

// RefinedProd(ldap,1999,Some(ddd))