通过FlowCollector而不是emit()发出数据无效

我有一个 BaseUseCase 类,以这种方式编排状态:

abstract class BaseUseCase<T, in P: UseCaseParameters> {

    protected abstract suspend fun FlowCollector<Result<T>>.run(params: P)

    operator fun invoke(params: P) =
        flow {
            emit(State.Loading)
            run(params)
            emit(State.Loaded)
        }.flowOn(Dispatchers.IO)
}

的预期输出 Flow.collect{} 范围是:

State.Loading
State.Success / State.Error // where I get the success or error data
State.Loaded

到目前为止,它对API调用等运行良好。现在,我有了一个特定的实现,从资产中读取JSON文件并将其发送到流中。对于这种情况,它只是在发射 Loading 和 Loaded 州。

以下是实现的其余部分:

ViewModel:

private fun getAllCards() {
        viewModelScope.launch {
            getAllCardsUseCase(None()).collect {
                val printData: String = when (it) {
                    is State -> it.toString()
                    is Failure -> it.errorData.message.toString()
                    is Success -> {
                        it.successData.cardList.first().name }
                }
                Timber.d("ALL CARDS RESPONSE = $printData")
            }
        }
    }

用例:

class GetAllCardsUseCase<T : ViewEntity> @Inject constructor(
    private val mapper: @JvmSuppressWildcards Mapper<ArrayList<Card>, T>,
    private val cardRepository: CardRepository
) : BaseUseCase<T, None>() {
    override suspend fun FlowCollector<Result<T>>.run(params: None) {
        cardRepository.getCardList(mapper = mapper)
    }
}

存储库:

override suspend fun <T : ViewEntity> getCardList(mapper: Mapper<ArrayList<Card>, T>): Result<T> =
    readCardListFromFile()?.let {
        Success(successData = mapper.convert(it))
    } ?: run {
        Failure(errorData = ParsingError())
    }

正在中成功检索JSON数据并将其映射到模型中 let{} 块

getCardList() 按预期返回成功状态,但它从未被发出。我错过了什么?