Config4k
Config for Kotlin.
Config4k is a lightweight Typesafe Config wrapper for Kotlin and inspired by ficus, providing simple extension functions Config.extract<T> and Any.toConfig to convert between Config and Kotlin Objects.
Table of Contents
Installation
Gradle:
repositories {
mavenCentral()
}
dependencies {
compile 'io.github.config4k:config4k:xxx' // See the `Download` badge
}
Usage
Delegated Properties
By far the simplest way to use config4k is via Kotlin Delegated Properties:
val config = ConfigFactory.parseString("""
|stringValue = hello
|booleanValue = true
|""".trimMargin())
val stringValue: String by config
println(stringValue) // hello
val nullableStringValue: String? by config
println(nullableStringValue) // null
val booleanValue: Boolean by config
println(booleanValue) // true
Deserialization
Config.extract<T> converts Config to T.
Map
Maps can be serialized with String keys
val config = ConfigFactory.parseString("""
|map {
| foo = 5
| bar = 6
|}""".trimMargin())
val map: Map<String, Int> = config.extract<Map<String, Int>>("map")
println(map["foo"] == 5) // true
println(map["bar"] == 6) // true
or with arbitrary keys
val config = ConfigFactory.parseString("""
|map = [{
| key = 5
| value = "foo"
|}
|{
| key = 6
| value = "bar"
|}]""".trimMargin())
val map: Map<Int, String> = config.extract<Map<Int, String>>("map")
println(map[5] == "foo") // true
println(map[6] == "bar") // true
Test Class: TestMap.kt
Data Classes
Config4k has no option to use different names between code and config file.
data class Person(val name: String, val age: Int)
val config = ConfigFactory.parseString("""
|key {
| name = "foo"
| age = 20
|}""".trimMargin())
val person: Person = config.extract<Person>("key")
println(person.name == "foo") // true
println(person.age == 20) // true
For more details, please see TestArbitraryType.kt
Nullable
Using extract<T?> is the better way than Config.hasPath(). extract<T?> returns T when the path exists and null when it does not exist.
val config = ConfigFactory.parseString("""key = 10""")
val key = config.extract<Int?>("key")
val foo = config.extract<Int?>("foo")
println(key == 10) // true
println(foo == null) // true
Test Class: TestNullable.kt
Enum
Config4k also supports Enum. Enum is converted to String of its name in the config file.
enum class Size {
SMALL,
MEDIUM,
LARGE
}
val config = ConfigFactory.parseString("""key = SMALL""")
val small = config.extract<Size>("key")
println(small == Size.SMALL) // true
Test Class: TestEnum.kt
Serialization
Any.toConfig converts the receiver object to Config.
String
You can use ConfigValue.render() to serialize Config. Config4k helps getting Config of the class you want to serialize.
data class Person(val name: String, val age: Int)
val person = Person("foo", 20).toConfig("person")
println(person.root().render())
Output:
{
# hardcoded value
"person" : {
# hardcoded value
"age" : 20,
# hardcoded value
"name" : "foo"
}
}
Test Class: TestToConfigForArbitraryType.kt
ConfigRenderOptions
Typesafe Config's class ConfigRenderOptions is the argument of ConfigValue.render.
// If setJson(false) is called, ConfigValue.render returns HOCON
data class Person(val name: String, val age: Int)
val person = Person("foo", 20).toConfig("person")
val options = ConfigRenderOptions.defaults().setJson(false)
println(person.root().render(options))
Output:
# hardcoded value
person {
# hardcoded value
age=20
# hardcoded value
name=foo
}
// setOriginComments(false) removes comments
data class Person(val name: String, val age: Int)
val person = Person("foo", 20).toConfig("person")
val options = ConfigRenderOptions.defaults()
.setJson(false)
.setOriginComments(false)
println(person.root().render(options))
Output:
person {
age=20
name=foo
}
Supported types
Property delegation, extract and toConfig support these types:
- Primitive types
BooleanByteIntLongFloatDouble
Stringimport java.io.Fileimport java.nio.file.Pathjava.time.Durationjava.time.Periodjava.time.temporal.TemporalAmountkotlin.text.Regex- Collections
ListSetMap<K, V>Array<T>(You can useArray<Int>, but can't useArray<Array<Int>>)
- Nullable
T? - Typesafe Config classes(Calling
toConfigis meaningless)com.typesafe.config.Configcom.typesafe.config.ConfigValuecom.typesafe.config.ConfigMemorySize
- Enum
- Data classes
See SelectReader.kt for the exhaustive list.
Snapshots
All snapshot artifacts are available in the Sonatype snapshots repository.
Contribute
Would you like to contribute to Config4k?
Take a look at CONTRIBUTING.md
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