Sync Android SDK/com.twilio.sync.client/Maps/mutateMapItem

mutateMapItem

abstract suspend fun mutateMapItem(mapSidOrUniqueName: String, itemKey: String, mutator: suspend (<Error class: unknown class>?) -> <Error class: unknown class>?): SyncMap.Item

Mutate value of the SyncMap.Item without opening SyncMap using provided Mutator function.

The Mutator function could be invoked more than once in case of data collision, i.e. if data on backend is modified while the mutate operation is executing. It guarantees that Mutator generates new value based on latest item data.

Possible use case is to implement distributed counter:

@Serializable
data class Counter(val value: Long = 0) {
    operator fun plus(x: Long) = Counter(value + x)
}

syncClient.maps.mutateItem<Counter>("mapName", "counter") { counter -> counter?.let { it + 1 } ?: Counter(1) }

Return

SyncMap.Item which has been set during mutation.

Parameters

mapSidOrUniqueName

SID or unique name of existing SyncMap.

itemKey

Key of the item to mutate.

mutator

Mutator which will be applied to the map item.

This function will be provided with the
previous data contents and should return new desired contents or null to abort
mutate operation. This function is invoked on a background thread.

Throws

TwilioException

When error occurred while mutating the Item.