这里是一个简单的例子，展示了如何更新数组值.我的文档有一个投票者数组，用于添加对文档进行投票的用户 ID.

Here is the simple example to show how to update the array values. My document have an up voters array to add the user id's who have up-votes the document.

配置 firestore，可以从您的 google-services.json 文件中复制配置详细信息

configure firestore, the config details can be copied form your google-services.json file

   final FirebaseApp app = await FirebaseApp.configure(
    name: 'test',
    options: const FirebaseOptions(
      projectID: 'projid',
      googleAppID: 'appid',
      apiKey: 'api',
      databaseURL: 'your url',
    ),
  );
  final Firestore firestore = Firestore(app: app);

  await firestore.settings(timestampsInSnapshotsEnabled: true);

使用交易更新代码

fireStore.runTransaction((Transaction tx) async {
            DocumentSnapshot snapshot =
                await tx.get(widget._document.reference);
            var doc = snapshot.data;
            if (doc['upvoters'].contains('12345')) {
              await tx.update(snapshot.reference, <String, dynamic>{
                'upvoters': FieldValue.arrayRemove(['12345'])
              });
            } else {
              await tx.update(snapshot.reference, <String, dynamic>{
                'upvoters': FieldValue.arrayUnion(['12345'])
              });
            }
          });

希望能帮到你