Corda: StateRef usage in a scheduled activity - corda

Question

Where do I provide the constructor input as the error message states? I am unsure of the correct usage of the StateRef when scheduling activities. I successfully ran the Heartbeat CorDapp for testing basic usage.
ForwardState:
data class ForwardState(val initiator: Party, val acceptor: Party, val asset: String, val deliveryPrice: BigDecimal, val startDate: Instant, val settlementDate: Instant, val buySell: String) : SchedulableState {
override val participants get() = listOf(initiator, acceptor)
override fun nextScheduledActivity(thisStateRef: StateRef, flowLogicRefFactory: FlowLogicRefFactory): ScheduledActivity? {
return ScheduledActivity(flowLogicRefFactory.create("com.template.ForwardSettleFlow"), settlementDate)
}
ForwardFlow:
#InitiatingFlow
#StartableByRPC
class ForwardFlow(val initiator: Party, val acceptor: Party, val asset: String, val deliveryPrice: BigDecimal,
val startDate: Instant, val settlementDate: Instant, val buySell: String) : FlowLogic<Unit>() {
companion object {
object GENERATING_TRANSACTION : ProgressTracker.Step("Generating transaction")
object SIGNING_TRANSACTION : ProgressTracker.Step("Signing transaction with our private key")
object FINALISING_TRANSACTION : ProgressTracker.Step("Recording transaction") {
override fun childProgressTracker() = FinalityFlow.tracker()
}
fun tracker() = ProgressTracker(
GENERATING_TRANSACTION,
SIGNING_TRANSACTION,
FINALISING_TRANSACTION
)
}
override val progressTracker = tracker()
#Suspendable
override fun call() {
// Adapted from hello world pt 1/2
}
}
ForwardSettleFlow:
#InitiatingFlow
#SchedulableFlow
#StartableByRPC
class ForwardSettleFlow(val initiator: Party, val acceptor: Party, val asset: String, val deliveryPrice: BigDecimal,
val startDate: Instant, val settlementDate: Instant, val buySell: String,
val thisStateRef: StateRef) : FlowLogic<Unit>() {
// progress tracker redacted
#Suspendable
override fun call() {
progressTracker.currentStep = GENERATING_TRANSACTION
val input = serviceHub.toStateAndRef<ForwardState>(thisStateRef)
val output = ForwardState(initiator, acceptor, asset, deliveryPrice, startDate, settlementDate, buySell)
val beatCmd = Command(ForwardContract.Commands.Settle(), ourIdentity.owningKey)
val txBuilder = TransactionBuilder(serviceHub.networkMapCache.notaryIdentities.first())
.addInputState(input)
.addOutputState(output, FORWARD_CONTRACT_ID)
.addCommand(beatCmd)
progressTracker.currentStep = SIGNING_TRANSACTION
val signedTx = serviceHub.signInitialTransaction(txBuilder)
progressTracker.currentStep = FINALISING_TRANSACTION
subFlow(FinalityFlow(signedTx))
}
}
ForwardFlow initiates and has a Responder for both party signing.
Scheduled activity setup to respond once the settlementDate has been reached via the ForwardSettleFlow and Responder. This flow accepts thisStateRef in the class constructor. Testing showed that leaving this out made no difference to the error output. This process has two flows and two respective responders.
The crash shell for Party A freezes around the time of FINALISING_TRANSACTION during the ForwardFlow.
rx.exceptions.OnErrorNotImplementedException: A FlowLogicRef cannot be
constructed for FlowLogic of type com.template.ForwardSettleFlow: due
to missing constructor for arguments: [class
net.corda.core.contracts.StateRef]
I believe this stops the activity from ever occurring, including when the contract is blank during testing with no requirements.

Answer 1

FlowLogicRefFactory.create() has the following constructor:
override fun create(flowClass: Class<out FlowLogic<*>>, vararg args: Any?): FlowLogicRef {
When you invoke FlowLogicRefFactory.create() in ForwardState.nextScheduledActivity(), you do not pass any arguments at all:
flowLogicRefFactory.create("com.template.ForwardSettleFlow")
But there is no ForwardSettleFlow constructor that takes zero arguments:
class ForwardSettleFlow(val initiator: Party, val acceptor: Party, val asset: String,
val deliveryPrice: BigDecimal, val startDate: Instant, val settlementDate: Instant,
val buySell: String, val thisStateRef: StateRef) : FlowLogic<Unit>() {
And thus you get a "missing constructor" exception. Either you need to update ForwardSettleFlow to have a zero-argument constructor, or you need to pass some arguments to FlowLogicRefFactory.create().