Firebase：如何检查用户身份验证是否被另一个提供商覆盖？

Question

目前，我有四种不同的提供商方法可以在我的应用中登录/创建帐户：

• 电子邮件和密码
• 谷歌
• 脸书
• 微软

当用户第一次通过其中一个提供商登录（或通过电子邮件和密码创建帐户）时，我会自动创建一个带有附加信息的 用户文档在云火库中。这是我的一个提供商（电子邮件和密码）的问题：

当用户使用提供商“电子邮件和密码”创建帐户时，他可以选择他/她喜欢的任何电子邮件，因此也可以使用 Google 或 Microsoft 电子邮件并提供错误的附加信息（错误的名称等）。然后，此错误信息将存储在用户创建帐户后我创建的 user-document 中。

如果上述用户未验证他的电子邮件并通过 Google 或 Microsoft 提供商登录，则旧的“电子邮件和密码”提供商将被覆盖，但不是我之前创建的错误 用户文档。

我的问题是：有没有办法观察或知道一个提供者被另一个提供者覆盖，因此也覆盖了错误的用户文档？

通用代码

// Check if user-document already exists, so it does not get overridden 
// when logging in via Google, Microsoft or Facebook-auth
private suspend fun isUserRegistered(): Boolean {
    val document = dbFirestore.collection(FIREBASE_USER_BASE_PATH).document(dbAuth.currentUser!!.uid).get().await()
    return document.exists()
}

private suspend fun createUserIfNotExist(user: UserNetworkEntity) {
    if (isUserRegistered()) return
    createUserAccount(dbAuth.currentUser!!.uid, user)
}

// Function to check whether user is verified and delete old doc if not verified 
// Here the user-data and the created user-doc will be verified via firebase-admin-sdk
private suspend fun callUserOnCheck(email: String): HttpsCallableResult? {
    return dbFunctions
        .getHttpsCallable(FUNCTION_USER_ON_CHECK_EMAIL)
        .call(hashMapOf<String, String?>("email" to email))
        .await()
}

Google 代码

override fun signInWithGoogle(account: GoogleSignInAccount): Flow<LoginStateEvent> = flow {
    val credential = GoogleAuthProvider.getCredential(account.idToken, null)

    // Delete old doc if not verified. Getting email from GoogleSignInAccount
    // IMPORTANT: We have to check the old document here, before calling dbAuth.signInWithCredential()
    // because #signInWithCredential() would override the old email-provider
    val email = account.email!!
    callUserOnCheck(email)

    dbAuth.signInWithCredential(credential).await()

    createUserIfNotExist(UserNetworkEntity(fullName = fullName))
}

Facebook 代码

override fun signInWithFacebook(): Flow<LoginStateEvent> = flow {
    val result = fLoginManager.registerMCallback(callbackManager)

    val credential = FacebookAuthProvider.getCredential(result.accessToken.token)

    // Delete old doc if not verified. Getting email from Facebook-GraphResponse
    // IMPORTANT: We have to check the old document here, before calling dbAuth.signInWithCredential()
    // because #signInWithCredential() would override the old email-provider
    callUserOnCheckFacebook(result.accessToken)

    dbAuth.signInWithCredential(credential).await()

    createUserIfNotExist(UserNetworkEntity(fullName = dbAuth.currentUser!!.displayName!!))
}

// Function to check whether user is verified. Special case: Get Facebook email via GraphResponce 
private suspend fun callUserOnCheckFacebook(accessToken: AccessToken) {
    val email = getFacebookEmail(accessToken)
    if (email != null) callUserOnCheck(email)
}

// Get Facebook email via GraphResponce without the need to login via #signInWithCredential()
private suspend fun getFacebookEmail(accessToken: AccessToken) = suspendCancellableCoroutine<String?> { cont ->
    val callback = GraphRequest.GraphJSONObjectCallback { json, response ->
        // OnError
        response?.error?.let { cont.resumeWithException(Throwable(it.errorMessage)) }

        // OnSucess
        cont.resume(json?.optString("email"), cont::resumeWithException)
    }

    GraphRequest.newMeRequest(accessToken, callback)
}

Microsoft 代码（如何解决 TODO？）

override fun signInWithMicrosoft(activity: Activity): Flow<LoginStateEvent> = flow {

   // TODO: Check whether old created user-doc is valid or not before calling
   // dbAuth.pendingAuthResult or ..startActivityForSignIn... as this would
   // override the old existing email-provider.
   // Question: How to get microsoft-email without calling #pendingAuthResult or #startActivityForSignIn ?
    
    val result = dbAuth.pendingAuthResult?.await() ?: dbAuth.startActivityForSignInWithProvider(
        activity,
        microsoftOAuth.build()
    ).await()

    createUserIfNotExist(UserNetworkEntity(fullName = result.user!!.displayName!!))
}

Answer 1

我想您可能正在寻找fetchSignInMethodsForEmail function。您可以将此用户的电子邮件传递给此用户，然后检查该电子邮件是否已与电子邮件+密码提供商一起使用（在这种情况下，您需要清理该文档）。