mutateItem

Mutate value of the existing Item 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)
}

list.mutateItem<Counter>(itemIndex = 0) { counter -> counter + 1 }

Parameters

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