How can I get the key in the onTimer function of a CoProcessFunction?

the onTimer method contains the parameter OnTimerContext you can simply call ctx.getCurrentKey() from there. hope it helps

Thanks, I tried that, but unfortunately I get an error -

The method getCurrentKey() is undefined for the type CoProcessFunction

ok I can give you some code snippets, see how they can correlate. We use kotlin, but should be the same: This is our class:

class ClusterProcessFunction :
    KeyedCoProcessFunction<String, AccountAndActivityTagged, UserActivity, CustomerClusterChangedEvent>() {

and this our onTimer method implementation:

override fun onTimer(timestamp: Long, ctx: OnTimerContext, out: Collector<CustomerClusterChangedEvent>) {
   ctx.currentKey
}

hope makes some sense?