Value types and Validation

When working with the library, first thing you run into is Validation. Every data that models entity from any source within library has strict constraints, own type that tells about data and so on. They're value objects from Domain-Driven Design.

Initiating such classes

All those types have one thing in common – ValueFactory in the Companion object.

All it does is that the Companion has function that creates needed for you instance – create. It returns kotlin.Result with the constructed value or with exception of type CreationFailure by contract.

The creation of such types can be done in the following ways:

// basic way
val clubTag: ClubTag = ClubTag.create("...")
    .getOrElse { throwable: Throwable -> /* ... */ }

// shortcut
val clubTag = ClubTag.createOr("...") { failure: CreationFailure ->
    // ...
}

// unsafe way (requires [[[opt-in|https://kotlinlang.org/docs/opt-in-requirements.html]]])
// if value is invalid, it will throw an Exception
@OptIn(ValueConstructor.Unsafe::calss)
val clubTag: ClubTag = ClubTag.createUnsafe("...")

For more information, you may want to see kotlidator sources.

Last modified: 04 January 2025