DataStore 未收到来自 Flow 的事件

Question

我正在使用 datastore-preferences:1.0.0-alpha01 并且当数据存储值更新时我似乎无法恢复事件。我一直试图在片段和父活动中观察它，结果相同。当我创建 DataStore 的实例并观察值流时，我在声明观察者后立即收到一个事件（注册观察者后似乎很常见）。这将表明流正在运行，并且观察者正在按预期接收事件。然后我在同一个观察者内部更新首选项的值，该观察者从不接收事件。

我使用这篇文章作为参考https://medium.com/scalereal/hello-datastore-bye-sharedpreferences-android-f46c610b81d5，它与我用来比较我的实现的 repo 一起使用。显然，这个是有效的。https://github.com/PatilShreyas/DataStoreExample

数据存储实用程序

class DataStoreUtils(context: Context) {

    companion object {
        private const val TAG = "DataStoreUtils"
    }

    private val dataStore = context.createDataStore(name = Constants.PrefName.APP_PREFS)

    suspend fun setString(prefKey: String, value: String) {
        Log.d(TAG, "Setting $prefKey to $value")
        dataStore.edit { it[preferencesKey<String>(prefKey)] = value }
    }

    suspend fun getString(prefKey: String): String? {
        return dataStore.data.map { it[preferencesKey<String>(prefKey)] ?: return@map null }.first()
    }

    val usernameFlow: Flow<String?> = dataStore.data
        .catch {
            if (it is IOException) {
                it.printStackTrace()
                emit(emptyPreferences())
            }
            else { throw it }
        }
        .map { it[preferencesKey(Constants.SharedPrefKeys.USERNAME)] ?: return@map null }

}

更新连接对话框

class UpdateConnectionDialog : DialogFragment() {

    companion object {
        private const val TAG = "UpdateConnectionDialog"
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        save_btn.setOnClickListener {
            runBlocking { authenticateResponse(ApiCalls.postLogin(body)!!) }
        }
    }

    override fun onResume() {
        super.onResume()

        dataStore ?: dataStore = DataStoreUtils(Application.appInstance?.applicationContext!!)

        dataStore.usernameFlow.asLiveData().observe(this) {
            Log.d(TAG, "Updated username to: $it")
        }
    }

    private fun authenticateResponse(response: ApiResponse<String>) {

        Log.d(TAG, "Auth request made.")

        when (response) {
            is ApiSuccessResponse<String> -> {
                AppLog.d(TAG, "Auth Success")

                lifecycleScope.launch {
                    dataStore.setString(Constants.PrefKeys.USERNAME, username_input.text.toString())
                    dataStore.setString(Constants.PrefKeys.PASSWORD, password_input.text.toString())
                }
            }
            is ApiErrorResponse<String> -> {
                AppLog.d(TAG, "Auth failed")
            }
        }
    }
}

当视图膨胀时，这就是我在日志中看到的

D/UpdateConnectionDialog: onCreateView()
D/UpdateConnectionDialog: onViewCreated()
D/UpdateConnectionDialog: onResume()
D/UpdateConnectionDialog: Updated username to: X // Seems to be common with other examples I have found. After registering an observer it immediately triggers the event.
D/UpdateConnectionDialog: Auth request made.
D/UpdateConnectionDialog: Auth Success
D/DataStoreUtils: Setting USERNAME to X
D/DataStoreUtils: Setting PASSWORD to X

现在，通过其他示例，我们应该看到观察者因已更新而触发事件，但我没有。对于其他示例，添加相同的日志记录点，很明显观察者收到了更新事件。