FieldValidator

Interface for custom field validators in Yacla configuration loading.

Implementations of this interface allow developers to enforce complex or domain-specific validation rules beyond simple annotations like @Required or @Range.

This interface is typically used in conjunction with the net.ririfa.yacla.annotation.CustomValidateHandler annotation, which attaches a validator to a specific field.

Validators may throw exceptions (e.g., IllegalArgumentException, IllegalStateException) to reject invalid values.

Example:

class UrlValidator : FieldValidator {
    override fun validate(fieldValue: Any?, configInstance: Any) {
        val url = fieldValue as? String ?: throw IllegalArgumentException("URL must be a string")
        if (!url.startsWith("https://")) {
            throw IllegalArgumentException("URL must start with https://")
        }
    }
}