Why setting value multiple times to UpdateBuilder fails?

[nallwhy]

I'm trying to make factory for test like below.

// Factory Example

val car0 = insert(carFactory())
val car1 = insert(carFactory()) { it[name] = "Model Y" }

abstract class EntityIdTable<Key : Comparable<Key>, E>(name: String = "") : IdTable<Key>(name) {
    abstract fun toEntity(row: ResultRow): E
}

typealias AttributeApplier<Key, E> = EntityIdTable<Key, E>.(InsertStatement<EntityID<Key>>) -> Unit
typealias Factory<Key, E> = Pair<EntityIdTable<Key, E>, AttributeApplier<Key, E>>

fun <Key : Comparable<Key>, E> get(table: EntityIdTable<Key, E>, id: Key): E? {
    return transaction { table.select { table.id eq id }.map(table::toEntity).firstOrNull() }
}

fun <Key : Comparable<Key>, E> insert(
    factory: Factory<Key, E>,
    attributeApplier: AttributeApplier<Key, E> = {}
): E {
    val (table, defaultAttributeApplier) = factory

    return transaction {
        table
            .insertAndGetId {
                ///////// here's the problem /////////
                defaultAttributeApplier(it)
                attributeApplier(it)
                /////////
            }
            .value
            .let { get(table, it)!! }
    }
}

fun carFactory(): Factory<Long, Car> {
    return Pair(CarsTable, {
        it[name] = "default name"
    })
}

It apply default attributes first and overwrite custom attributes.
But when it tries to overwrite custom attributes, it fails.

java.lang.IllegalStateException: com.example.Car.name is already initialized

	at org.jetbrains.exposed.sql.statements.UpdateBuilder.set(UpdateBuilder.kt:17)

And I found that UpdateBuilder blocks setting value multiple times to single key.

abstract class UpdateBuilder<out T>(type: StatementType, targets: List<Table>): Statement<T>(type, targets) {
    ....

    open operator fun <S> set(column: Column<S>, value: S) {
        when {
            values.containsKey(column) -> error("$column is already initialized")
            !column.columnType.nullable && value == null -> error("Trying to set null to not nullable column $column")
            else -> values[column] = value
        }
    }
    ...
}

I have no idea why it is necessary.
I want to bypass this constraint. Can I do that?

Thanks.

[vlsi]

@Tapac , sorry for pinging, however, can you please clarify what is the point behind "is already initialized" verification?
I ran across the very same case as nallwhy: I thought I could set "default value" first, and then override it with a more specific one, however, Exposed rejects that code.

Do you think "$column is already initialized" verification could be removed?

[Tapac]

Agree, it's a legacy check. Will be removed in the next release.