konstant-core/io.github.fiol_dev.konstant.core/ConfigLoader

ConfigLoader

Reads config values from a list of sources. The KSP processor adds a load<Spec>() extension for each @ConfigSpec class, which returns a ConfigResult:

val loader = ConfigLoader {
    sources {
        +EnvSource()
        +TomlSource.fromFile("config.toml")
    }
}
val config = loader.loadAppConfig().getOrThrow()

Constructors

ConfigLoader

constructor(block: ConfigLoaderBuilder.() -> Unit)

Creates a loader with the sources declared in block's ConfigLoaderBuilder.sources.

Properties

sources

val sources: List<ConfigSource>

The sources in priority order: for each field, the first source that has a value wins, and later sources are only asked when earlier ones have none.

Functions

explain

fun <T> explain(load: ConfigLoader.() -> ConfigResult<T>): ConfigReport<T>

Runs load and reports, for every field, the value used and which source it came from. Secrets are shown as ***. A value that fails conversion or validation is still listed with its source; the error itself is in ConfigReport.result. Useful for debugging which file or variable won:

loadOptional

fun <T> loadOptional(prefix: String, load: ConfigLoader.(String) -> ConfigResult<T>): ConfigResult<T>?

Loads a nullable nested spec under prefix. Returns null, so the field gets its default, when no source has any of the spec's keys; otherwise the spec loads as usual, and missing required keys are errors. Called by generated code.

resolve

fun <T> resolve(field: FieldDescriptor<T>, prefix: String?): ResolveResult<T>

Resolves one field from the sources in priority order. Called by generated code.