To use PureConfig in an existing SBT project with Scala 2.11 or a later version, add the following dependency to your
libraryDependencies += "com.github.pureconfig" %% "pureconfig" % "0.10.2"
For a full example of
build.sbt you can have a look at this build.sbt.
Earlier versions of Scala had bugs which can cause subtle compile-time problems in PureConfig. As a result we recommend only using the latest Scala versions within the minor series.
In your code, import
pureconfig.generic.auto and define data types and a case class to hold the configuration:
import pureconfig.generic.auto._ sealed trait MyAdt case class AdtA(a: String) extends MyAdt case class AdtB(b: Int) extends MyAdt final case class Port(value: Int) extends AnyVal case class MyClass( boolean: Boolean, port: Port, adt: MyAdt, list: List[Double], map: Map[String, String], option: Option[String])
Second, define an
application.conf file like
this and add it as a
resource file of your application (with SBT, they are usually placed in
Finally, load the configuration:
pureconfig.loadConfig[MyClass] // res0: pureconfig.ConfigReader.Result[MyClass] = Right(MyClass(true,Port(8080),AdtB(1),List(1.0, 0.2),Map(key -> value),None))
ConfigReader.Result[MyClass] is just an alias for
Either[ConfigReaderFailures, MyClass], so you can handle it just like you
would handle an
loadConfig methods defer to Typesafe Config’s
select where to load the config files from. Typesafe Config has well-documented rules for configuration
loading which we’ll not repeat. Please see Typesafe
Config’s documentation for a full telling of the subtleties.
Alternatively, PureConfig also provides a
loadConfigFromFiles method that builds a configuration from
an explicit list of files. Files earlier in the list have greater precedence than later ones. Each file can
include a partial configuration as long as the whole list produces a complete configuration. For an example,
see the test of
Because PureConfig uses Typesafe Config to load configurations, it supports reading files in HOCON, JSON, and Java
.properties formats. HOCON is a delightful superset of both JSON and
.properties that is highly recommended. As an added bonus it supports advanced features like variable substitution and file sourcing.