如何使用 Flutter 配置 Firebase Firestore 设置

Question

我正在评估Firestore Plugin for Flutter。

这个 sn-p 按预期工作，它在按下浮动按钮时将一条记录插入到 firestore：

import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  Firestore firestore;

  _MyHomePageState() {
    firestore = Firestore.instance;
  }

  void _addBoard() {
    setState(() {
      _counter++;
      firestore.collection("boards").document().setData({ 'name': 'mote_$_counter', 'descr': 'long descr $_counter' });
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(widget.title),
      ),
      body: new Center(
        child: new Column(
         mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new Text(
              'You have pushed the button this many times:',
            ),
            new Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _addBoard,
        child: new Icon(Icons.add),
      ), 
  }
}

使用flutter run 运行控制台显示警告：

W/Firestore(31567): (0.6.6-dev) [Firestore]: The behavior for java.util.Date objects stored in Firestore is going to change AND YOUR APP MAY BREAK.
W/Firestore(31567): To hide this warning and ensure your app does not break, you need to add the following code to your app before calling any other Cloud Firestore methods:
W/Firestore(31567): 
W/Firestore(31567): FirebaseFirestore firestore = FirebaseFirestore.getInstance();
W/Firestore(31567): FirebaseFirestoreSettings settings = new FirebaseFirestoreSettings.Builder()
W/Firestore(31567):     .setTimestampsInSnapshotsEnabled(true)
W/Firestore(31567):     .build();
W/Firestore(31567): firestore.setFirestoreSettings(settings);
W/Firestore(31567): 
W/Firestore(31567): With this change, timestamps stored in Cloud Firestore will be read back as com.google.firebase.Timestamp objects instead of as system java.util.Date objects. So you will also need to update code expecting a java.util.Date to instead expect a Timest        

有一种方法可以配置 FirebaseFirestore 实例，从而通过日期设置解决此问题？

Answer 1

从cloud_firestore 0.8.2解决问题，先将pubspec.yaml中的依赖升级为：

dependencies:
  cloud_firestore: ^0.8.2+1

Firestore::setting 返回一个 Future，因此必须在异步函数中调用它。

这足以使示例代码工作：

void main() async {
  final Firestore firestore = Firestore();
  await firestore.settings(timestampsInSnapshotsEnabled: true);

  runApp(new MyApp());
}

然后，在实际添加文档时，显式添加一个 createdAt（或任何你想称呼它的名称）字段，如下所示：

    Firestore.instance
        .collection('customer')
        .add({
      "name": customerNameController.text,
      "createdAt": FieldValue.serverTimestamp()
    }).then((res) { ...

Answer 2

应该在 0.8.2 版本中解决。

请参阅example 了解如何使用设置。