将状态标记为已使用而不更改其在Corda中的内容 [英] Marking a state as consumed without changing its contents in Corda

问题描述

我正在研究一个简单的用例，其中需要将状态作为事务中的输入并生成新的输出状态.但是我希望状态的内容是相同的.我只想将输入状态标记为已消耗，并生成具有相同内容的新输出状态.我正在编写的Cordapp使用Java.

I am working on a simple use case in which I need to take a state as an input in a transaction and generate a new output state. But I want the contents of the state to be the same. I just want to mark the input state as consumed and generate a new output state with the same contents. The Cordapp I am writing is in Java.

我该如何在Corda中做到这一点?

How can i do that in Corda?

推荐答案

为此，您需要执行三个步骤:

To do this, you need to perform three steps:

1. 检索要使用的输入状态
2. 将输出状态设为输入状态的副本
3. 将它们都添加到交易生成器中

这是在代表义务的状态下执行此操作的示例:

Here's an example of doing this for a state representing an obligation:

// Retrieve the state using its linear ID.
QueryCriteria queryCriteria = new QueryCriteria.LinearStateQueryCriteria(
        null,
        ImmutableList.of(linearId),
        Vault.StateStatus.UNCONSUMED,
        null);

List<StateAndRef<Obligation>> obligations = getServiceHub().getVaultService().queryBy(Obligation.class, queryCriteria).getStates();
if (obligations.size() != 1) {
    throw new FlowException(String.format("Obligation with id %s not found.", linearId));
}
StateAndRef<Obligation> inputStateAndRef = obligations.get(0);
Obligation input = inputStateAndRef.getState().getData();

// Create the new output state.
Obligation output = new Obligation(input.getAmount(), input.getLender(), input.getBorrower(), input.getPaid(), input.getLinearId());

// Creating the transaction builder (don't forget to add a command!)
final TransactionBuilder builder = new TransactionBuilder(notary)
        .addInputState(inputStateAndRef)
        .addOutputState(output, OBLIGATION_CONTRACT_ID);

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