Quarkus + Kotlin + Hibernate Reactive + Panache: Accessing @OneToMany properties in companion class

[alecStewart1]

Hello, so maybe this is just a "I have read the docs" thing, but, as example, I have the following entity classes that I'll be using the the active record style:

(As of note, I'm still fairly new to Kotlin.)

Singular building entity that belongs to a county:

@Entity
@Serializable
class Building(
    @JoinColumn(name = "COUNTY_ID")
    @ManyToOne(optional = false)
    var county: County
) : PanacheEntity()  {

    companion object : PanacheCompanion<Building> {
        fun getAllBuildings(): Uni<Set<Building>> = CollectionConverts.uniListToSet(listAll())
        fun getActiveBuildings(): Uni<Set<Building>> = CollectionConverts.uniListToSet(list("where optOut = false and status = 'ACTIVE'"))
    }

    lateinit var name: String

    @Enumerated(EnumType.STRING)
    lateinit var status: Status

    var optOut: Boolean by Delegates.notNull()
}

The entity class that will have many buildings to one county.

@Entity
@Serializable
class County : PanacheEntity() {
    companion object: PanacheCompanion<Building> {
        fun buildingCount(): Uni<Long> = count("buildings") // I'm assuming with won't work either
        // This list() will return  Uni<List<County>> and not Uni<List<Building>>
        //fun getBuildingsInCounty(): Uni<Set<Building>> = CollectionConverts.uniListToSet(list("select cnty.buildings from County cnty"))
    }

    lateinit var name: String

    var zipCode: Int by Delegates.notNull()

    @OneToMany(
        mappedBy = "county",
        targetEntity = Building::class,
        cascade = [(CascadeType.ALL)],
        fetch = FetchType.LAZY
    )
    lateinit var buildings: MutableSet<Building>
}

The commented out function in the companion class is where I'm having issues.

The utility class CollectionConverts, if anyone needs to see it:

object CollectionConverts {
    fun <T> uniListToSet(uniList: Uni<List<T>>): Uni<Set<T>> = uniList.map { lst: List<T> -> HashSet<T>(lst) }
    fun <T> uniListToLinkedSet(uniList: Uni<List<T>>): Uni<Set<T>> = uniList.map { lst: List<T> -> LinkedHashSet<T>(lst) }
}

I guess my confusion is related to PanacheQuery, it's functions and how it interacts with Hibernate entities, or maybe it's really just something I didn't read about companion objects in Kotlin. I have worked with Hibernate and HQL before, so that's not entirely new to me.

[quarkus-bot[bot]]

/cc @DavideD (hibernate-reactive), @FroMage (panache), @gavinking (hibernate-reactive), @geoand (kotlin), @loicmathieu (panache)

[alecStewart1]

Ah, apologies. The question still stands, however I forgot that this should be done with an ID parameter for a County. That's also useful for when I get to caching the results of these functions.

// The companion object function I'm struggling with would be more like the following
fun getBuildingsInCounty(id: Long): Uni<Set<Building>> {
    val baseList: Uni<List<Building>> = list("select cnty.buildings from County cnty where cnty.id = :id", Parameters.with("id", id).map())
    return CollectionConverts.uniListToSet(baseList)
}