Miscellaneous

Miscellaneous features

Explicit instantiators

Normally, Lonk will automatically detect the best way to instantiate your classes based on database results. If a class has multiple constructors, this can be ambiguous. If you wish to be more explicit, annotate your preferred constructor — or a companion object function that returns an instance of the class — with @DbInstantiator. This causes Lonk to ignore all other constructors. It is an error to annotate more than one constructor or function this way.

Custom result collectors

If you need full control over how the whole result set is processed — rather than just mapping each row on its own with a ResultRowMapper — you can supply a ResultRowCollector. (The example below counts rows just to keep things simple; in real code you’d just write select count(*).)

val rowCount = conn.query("select * from department").collect(object : ResultRowCollector<Int> {
    private var rows = 0

    override fun accumulate(row: ResultRow): Boolean {
        rows++
        return true
    }

    override fun finish() = rows
})