Input Converters

Partiture attempts to decouple input and TX processing in flows. For that purpose, PartitureFlow.processInput() attempts to use the inputConverter passed via it's constructor to initialize the CallContext. If inputConverter is null, an error will be thrown.

You may find it convenient to override processInput(), e.g. for the first version of the flow in the introduction page:

/** Override to manually init the flow's CallContext */
override fun processInput(): CallContext {
    val entries = input.map { party ->
        // Prepare a TX builder
        val txBuilder = TransactionBuilderWrapper(clientFlow.getFirstNotary())
                .addOutputState(
                    YoContract.YoState(clientFlow.ourIdentity, input.recepient, input.message),
                    YO_CONTRACT_ID)
                .addCommand(YoContract.Send())
        // Return a TX context with builder and participants
        return CallContext(CallContextEntry(txBuilder))
    }
    return CallContext(entries)
}

however, the recommended way is implementing an InputConverter instead. In the case of YoFlow, the PartitureFlow's IN generic argument is List<Party> so we need to implement an InputConverter<List<Party>>:

class YoInputConverter : PartitureFlowDelegateBase(), InputConverter<List<Party>> {
    override fun convert(input: List<Party>): CallContext {
        val entries = input.map { party ->
            // Prepare a TX builder
            val txBuilder = TransactionBuilderWrapper(clientFlow.getFirstNotary())
                    .addOutputState(
                        YoContract.YoState(clientFlow.ourIdentity, input.recepient, input.message),
                        YO_CONTRACT_ID)
                    .addCommand(YoContract.Send())
            // Return a TX context with builder and participants
            return CallContext(CallContextEntry(txBuilder))
        }
        return CallContext(entries)
    }
}

the converter can then be reused between different flows by passing an instance as the inputConverter in PartitureFlow's constructor when extending it. See the second flow version in the introduction for an example.