Kotlin流发出但未接收到收集

huangapple
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英文:

Kotlin flow emits but collect is not receiving

问题

我有这个基本的流发射/收集代码，但收集部分没有接收到任何发射。

  1. object TodoRepository {
  2.     fun getTodos(): Flow<List<Todo>> = flow {
  3.         val data = KtorClient.httpClient.use {
  4.             it.get("...")
  5.         }
  6.         val todos = data.body<List<Todo>>()
  7.         emit(todos) // << emit 被调用
  8.     }.flowOn(Dispatchers.IO)
  9. }
  11. class TodoViewModel: ViewModel() {
  12.     val response = MutableSharedFlow<List<Todo>>()
  14.     init {
  15.         viewModelScope.launch {
  16.             TodoRepository.getTodos().collect {
  17.                 // 从未被调用!!!
  18.                 response.emit(it)
  19.             }
  20.         }
  21.     }
  22. }
  24. class MainActivity: AppCompatActivity() {
  25.     private val todoViewModel: TodoViewModel by viewModels()
  27.     override fun onCreate(savedInstanceState: Bundle?) {
  28.         super.onCreate(savedInstanceState)
  29.         setContentView(R.layout.activity_main)
  31.         runBlocking {
  32.             todoViewModel.response.collect {
  33.             }
  34.         }
  35.     }
  36. }
英文:

I have this basic flow emit / collect code but collect is not receiving any emits.

  1. object TodoRepository {
  2.     fun getTodos(): Flow&lt;List&lt;Todo&gt;&gt; = flow {
  3.         val data = KtorClient.httpClient.use {
  4.             it.get(&quot;...&quot;)
  5.         }
  6.         val todos = data.body&lt;List&lt;Todo&gt;&gt;()
  7.         emit(todos) // &lt;&lt; emit is called
  8.     }.flowOn(Dispatchers.IO)
  9. }
  11. class TodoViewModel: ViewModel() {
  12.     val response = MutableSharedFlow&lt;List&lt;Todo&gt;&gt;()
  14.     init {
  15.         viewModelScope.launch {
  16.             TodoRepository.getTodos().collect {
  17.                 // NEVER INVOKED !!!
  18.                 response.emit(it)
  19.             }
  20.         }
  21.     }
  22. }
  24. class MainActivity: AppCompatActivity() {
  25.     private val todoViewModel: TodoViewModel by viewModels()
  27.     override fun onCreate(savedInstanceState: Bundle?) {
  28.         super.onCreate(savedInstanceState)
  29.         setContentView(R.layout.activity_main)
  31.         runBlocking {
  32.             todoViewModel.response.collect {
  33.             }
  34.         }
  35.     }
  36. }

答案1

得分: 0

感谢 @Tenfour04 的评论。runBlocking 是问题所在。例如，以下代码将有效：

  1. CoroutineScope(Dispatchers.Main).launch {
  2.     todoViewModel.response.collect {
  3.     }
  4. }
英文:

Thanks to @Tenfour04 comment. runBlocking was the problem. For example, this will work

  1.     CoroutineScope(Dispatchers.Main).launch {
  2.         todoViewModel.response.collect {
  3.         }
  4.     }

huangapple
  • 本文由 发表于 2023年1月9日 04:12:45
  • 转载请务必保留本文链接：https://go.coder-hub.com/75050952.html
  • android
  • kotlin
  • kotlin-coroutines
  • kotlin-flow
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