Firestore交易失败，并显示“交易失败所有重试". [英] Firestore transaction fails with "Transaction failed all retries"

问题描述

我正在运行一个非常简单的Firestore事务，该事务会在文件不存在之前先检查文件是否存在.

I'm running a very simple Firestore transaction which checks for the presence of a document, before writing to it if absent.

(用例正在注册用户名-如果尚未注册，则当前用户可以获取它)

(The use case is registering a username - if it's not already registered, the current user gets to grab it)

以下是相关的Flutter代码的片段:

Here's a snippet of the relevant Flutter code:

DocumentReference usernameDocRef =
    Firestore.instance.collection(_USERNAMES).document(username);

await Firestore.instance.runTransaction((transaction) async {
  var snapshot = await transaction.get(usernameDocRef);
  if (!snapshot.exists) {
    transaction.set(usernameDocRef, {
      _UsernamesKey.userid: _user.id,
    });
  }
});

此操作失败，但出现异常事务重试所有重试失败".

This is failing with an exception "Transaction failed all retries".

基于 Firestore文档，可能会发生故障两个原因:

Based on the Firestore documentation, failure can occur for two reasons:

• 事务在写操作之后包含读操作.读取操作必须始终在任何写入操作之前进行.
• 该事务读取了在事务外部修改的文档.在这种情况下，事务将自动再次运行.交易被重试了有限次.

• The transaction contains read operations after write operations. Read operations must always come before any write operations.
• The transaction read a document that was modified outside of the transaction. In this case, the transaction automatically runs again. The transaction is retried a finite number of times.

我认为我不会触发任何一个.有什么建议吗?

I don't think I trigger either of those. Any suggestions?

推荐答案

最近已修复- https://github.com/flutter/plugins/pull/1206 .

如果您使用的是主频道，该修复程序应该已经可用.对于其他渠道(开发，测试版，稳定版)YMMV.

If you are using the master channel, the fix should be available already. For the other channels (dev, beta, stable) YMMV.

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