Sync Android SDK/com.twilio.sync.client/Lists/mutateListItem

mutateListItem

abstract suspend fun mutateListItem(listSidOrUniqueName: String, itemIndex: Long, mutator: suspend (<Error class: unknown class>) -> <Error class: unknown class>?): SyncList.Item

Mutate value of the existing SyncList.Item without opening it 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.lists.mutateItem<Counter>("listName", itemIndex = 0) { counter -> counter + 1 }
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Return

SyncList.Item which has been set during mutation.

Parameters

listSidOrUniqueName

SID or unique name of existing SyncList.

itemIndex

Index of the item to mutate.

mutator

Mutator which will be applied to the list 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.
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Throws

TwilioException

When error occurred while mutating the Item.