Android Room Persistence Library: Upsert

Question

Android\'s Room persistence library graciously includes the @Insert and @Update annotations that work for objects or collections. I however have a use case (push notificatio

Answer 1

If you have legacy code: some entities in Java and BaseDao as Interface (where you cannot add a function body) or you too lazy for replacing all implements with extends for Java-children.

Note: It works only in Kotlin code. I'm sure that you write new code in Kotlin, I'm right? :)

Finally a lazy solution is to add two Kotlin Extension functions:

fun  BaseDao.upsert(entityItem: T) {
    if (insert(entityItem) == -1L) {
        update(entityItem)
    }
}

fun  BaseDao.upsert(entityItems: List) {
    val insertResults = insert(entityItems)
    val itemsToUpdate = arrayListOf()
    insertResults.forEachIndexed { index, result ->
        if (result == -1L) {
            itemsToUpdate.add(entityItems[index])
        }
    }
    if (itemsToUpdate.isNotEmpty()) {
        update(itemsToUpdate)
    }
}