Question

我正在读取Firestore事务中的几条记录并更新一些记录。如果不是，则所有记录更新的事务失败。它尝试重新运行事务，但由于平台异常“事务已完成”而失败。随附日志和简化的代码示例。

日志：

I/flutter (11935): Transaction try
I/flutter (11935): Transaction try
I/flutter (11935): >>>>>>>>>>>>>> Exception within transaction <<<<<<<<<<<<<<<<
I/flutter (11935): PlatformException(Error performing Transaction#get, Transaction has already completed., null)
I/flutter (11935): #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:569:7)
I/flutter (11935): #1      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:316:33)
I/flutter (11935): <asynchronous suspension>
I/flutter (11935): #2      MethodChannel.invokeMapMethod (package:flutter/src/services/platform_channel.dart:344:48)
I/flutter (11935): <asynchronous suspension>
I/flutter (11935): #3      Transaction._get (package:cloud_firestore/src/transaction.dart:27:10)
I/flutter (11935): <asynchronous suspension>
I/flutter (11935): #4      Transaction.get (package:cloud_firestore/src/transaction.dart:20:45)
I/flutter (11935): #5      _MyAppState.build.<anonymous closure>.<anonymous closure> (package:biblosphere/main.dart:391:54)
I/flutter (11935): <asynchronous suspension>
I/flutter (11935): #6      new Firestore.<anonymous closure> (package:cloud_firestore/src/firestore.dart:30:54)
I/flutter (11935): <asynchronous suspension>
I/flutter (11935): #7      MethodChannel._handleAsMethodCall (package:flutter/src/services/platform_channel.dart:397:55)
I/flutter (11935): <asynchronous suspension>
I/flutter (11935): #8      MethodChannel.setMethodCallHandler.<anonymous closure> (package:flutter/src/services/platform_channel.dart:365:

代码示例：

    DocumentReference docRef1 = Firestore.instance.collection('col1').document();
    await docRef1.setData({'name': 'John'});

    DocumentReference docRef2 = Firestore.instance.collection('col1').document();
    await docRef2.setData({'number': 0}); // This code fails
    //await docRef2.setData({'number': 1}); // This code works

    await db.runTransaction((Transaction tx) async {
      try {
        print('Transaction try');
        DocumentSnapshot docSnap1 = await tx.get(docRef1);
        if (!docSnap1.exists)
          throw ('Record does not exist in DB');

        DocumentSnapshot docSnap2 = await tx.get(docRef2);
        if (!docSnap2.exists)
          throw ('Record does not exist in DB');

        if (docSnap2.data['number'] == 0) {
          // Pay reward to the owner
          await tx.update(docRef1, {'name': 'Peter'});
        } else {
          await tx.update(docRef1, {'name': 'Mary'});
          await tx.update(docRef2, {'number': 2});
        }
      } catch (ex, stack) {
        print(
            '>>>>>>>>>>>>>> Exception within transaction <<<<<<<<<<<<<<<<');
        print(ex);
        print(stack);
      }
    });

我扑扑的医生：

    [√] Flutter (Channel stable, v1.9.1+hotfix.5, on Microsoft Windows [Version 10.0.18362.418], locale en-US)
    • Flutter version 1.9.1+hotfix.5 at D:\Flutter
    • Framework revision 1aedbb1835 (4 days ago), 2019-10-17 08:37:27 -0700
    • Engine revision b863200c37
    • Dart version 2.5.0


[√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at C:\Users\DenisStark\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-29, build-tools 28.0.3
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
    • All Android licenses accepted.

[√] Android Studio (version 3.3)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin version 33.3.1
    • Dart plugin version 182.5215
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)

[!] VS Code (version 1.39.2)
    • VS Code at C:\Users\DenisStark\AppData\Local\Programs\Microsoft VS Code
    X Flutter extension not installed; install from
      https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter

[√] Connected device (1 available)
    • VKY L29 • QYJ7N17524000190 • android-arm64 • Android 9 (API 28)

! Doctor found issues in 1 category.

我可以通过对事务中读取的所有记录进行虚拟更新来解决。但是我怀疑这是cloud_firestore插件中的错误。您有什么建议？

如果某些记录已读取但未更新，则Flutter Firestore事务将失败

0 个答案: