withContext 总是返回 false

Question

ViewModel class:

            // Update the userInformation and returns Boolean if the operation succeed
            val res = viewModelScope.async {
                accountRepository.update(
                    userId,
                    firstName,
                    lastName,
                    birthDate,
                    photoUrl
                )
            }

            // This should execute
            // But the result is always false and go to the else part.
            if (res.await()) {
                ...
            } else {
                // But it always goes here
                ...
            }

我的仓库中的更新功能正在执行，我可以看到Firestore中的变化，没有问题。但结果总是错误的，ViewModel 在我看来给出了错误的状态，我不喜欢它。我认为问题出在 withContext 部分。我不完全理解，但也许你可以给我一些关于如何解决这个问题的见解。我

这是我的 AccountRepository 的代码 class:

// Account Repository
// Update the user information
suspend fun update(
    userId: String,
    firstName: String,
    lastName: String,
    birthDate: String,
    avatarUrl: String
): Boolean {
    return withContext(dispatcher) {
        // This will be true for now
        var isSuccess = true

        // Parsing the date string "01/01/2000" to a date object
        val date = SimpleDateFormat("MM/dd/yyyy", Locale.ENGLISH).parse(birthDate)

        // Creating an instance of calendar object
        val calendarDate = Calendar.getInstance()
        // Set the time with the date variable
        calendarDate.time = date!!

        // Check if the user is in the right age to use the application
        // User should be 12 years old and above to access this app
        if (Calendar.getInstance().get(Calendar.YEAR)
            .minus(calendarDate.get(Calendar.YEAR)) >= 12
        ) {

            // Create a map to update fields in the firebase
            val updateUserMap = mapOf<String, Any>(
                "avatarUrl" to avatarUrl,
                "firstName" to firstName,
                "lastName" to lastName,
                "birthDate" to birthDate,
                "dateModified" to Utils.getTimeInMillisUTC()
            )

            // Execute the query in fireStore
            // I'm using ktx gradle library
            // This line executes. It reflects the changes in the fireStore
            val result = userCollectionRef
                .document(userId)
                .set(updateUserMap, SetOptions.merge())
                .await()

            // The variable will be changed to false when the result is null
            // Meaning that the query is not successful
            if (result == null) {
                isSuccess = false
            }
        }
        // Return the variable after all operations
        isSuccess
    }
}

Answer 1

The variable will be changed to false when the result is null Meaning that the query is not successful

我认为这是你错的地方。从docs来看，好像document.set()只是returns一个task，会在query结束的时候完成，但是并没有说null会被用作marker of失败。

此外，您正在使用的 await 函数会将 Task 失败表示为抛出的异常（这在协程中很常见，我们通常将挂起函数中的失败视为其他函数中的失败函数）。

如果你想处理错误，你应该使用 try-catch 而不是 if (result == null)。

withContext 总是返回 false

withContext is always returning false

android

kotlin

mvvm

viewmodel