Question

我要有一个输入国（状态A和合同A）和输出国（状态B和合同B）。我们可以将其合并到单个交易中吗？另外，如何调用两个不同合同的验证方法？如果将示例与响应共享，将非常有帮助。谢谢。

Answer 1

是的，这是可能的，并且整个交易都调用了两个合同。有效地，该节点运行：

ContractA().verify(transaction)
ContractB().verify(transaction)

因此，在编写两个verify方法时必须小心。通常，您将需要编写每个合同的verify方法，以便它仅查看与该合同相关的命令和状态。例如：

class ExampleContract : Contract {
    companion object {
        val ID = "com.example.ExampleContract"
    }

    interface ExampleCommands : CommandData {
        class Issue : ExampleCommands
        class Transfer : ExampleCommands
        class Exit: ExampleCommands
    }

    override fun verify(tx: LedgerTransaction) {
        val exampleCommands = tx.commandsOfType<ExampleCommands>()
        val exampleInputs = tx.inputsOfType<ExampleState>()
        val exampleOutputs = tx.outputsOfType<ExampleState>()

        exampleCommands.forEach { command ->
            when (command.value) {
                is ExampleCommands.Issue -> {
                    if (exampleInputs.isNotEmpty()) throw IllegalArgumentException("Issuance should have no inputs.")
                    if (exampleOutputs.isEmpty()) throw IllegalArgumentException("Issuance should have outputs.")
                    // TODO: More verification.
                }

                is ExampleCommands.Transfer -> {
                    if (exampleInputs.isEmpty()) throw IllegalArgumentException("Transfer should have inputs.")
                    if (exampleOutputs.isEmpty()) throw IllegalArgumentException("Transfer should have outputs.")
                    // TODO: More verification.
                }

                is ExampleCommands.Exit -> {
                    if (exampleInputs.isEmpty()) throw IllegalArgumentException("Exit should have inputs.")
                    if (exampleOutputs.isNotEmpty()) throw IllegalArgumentException("Exit should have no outputs.")
                    // TODO: More verification.
                }
            }
        }
    }
}

一次交易中有多个合同

1 个答案: