错误：没有名为'merge'的参数

Question

我刚开始学习Flutter，尝试将一个简单的待办事项应用连接到Firestore。为此，我想使用setOption 'merge'，以便之前的列表不会被删除。但是，每次我尝试调试时，都会收到错误消息“没有名为'merge'的参数”。以下是带有 merge 的代码：

import 'package:cloud_firestore/cloud_firestore.dart';

class DatabaseService {
  final String userID;
  DatabaseService(this.userID);

  final CollectionReference userToDos =
      FirebaseFirestore.instance.collection('userToDos');

  Future setTodo(String key, bool value) async {
    return await userToDos.doc(userID).set({key: value}, merge: true);
  }

  Future deleteTodo(String key) async {
    return await userToDos.doc(userID).update({
      key: FieldValue.delete(),
    });
  }

这是其余的代码：

import 'package:flutter/material.dart';
import 'add_item_dialog.dart';
import 'to_do_item.dart';
import 'database.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

void main() => runApp(MaterialApp(home: ToDo()));

class ToDo extends StatefulWidget {
  @override
  _ToDoState createState() => _ToDoState();
}

class _ToDoState extends State<ToDo> {
  User user;
  DatabaseService database;

  void addItem(String key) {
    database.setTodo(key, false);
    Navigator.pop(context);
  }

  void deleteItem(String key) {
    database.deleteTodo(key);
  }

  void toggleDone(String key, bool value) {
    database.setTodo(key, !value);
  }

  void newEntry() {
    showDialog<AlertDialog>(
        context: context,
        builder: (BuildContext context) {
          return AddItemDialog(addItem);
        });
  }

  Future<void> connectToFirebase() async {
    final FirebaseAuth authenticate = FirebaseAuth.instance;
    UserCredential result = await authenticate.signInAnonymously();

    user = result.user;

    // get [DatabaseService] instance for current user
    database = DatabaseService(user.uid);

    if (!(await database.checkIfUserExists())) {
      database.setTodo('Todo anlegen', false);
    }

    Stream userDocumentStream = database.getTodos();
    userDocumentStream
        .listen((documentSnapshot) => print(documentSnapshot.data));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('To-Do-App'),
        backgroundColor: Color.fromRGBO(35, 152, 185, 100),
      ),
      body: FutureBuilder(

          //  Wait until [connectToFirebase] returns stream
          future: connectToFirebase(),
          builder: (BuildContext context, AsyncSnapshot<void> snapshot) {
            if (snapshot.connectionState == ConnectionState.waiting) {
              return Center(child: CircularProgressIndicator());
            } else {
              // When stream exists, use Streambilder to wait for data
              return StreamBuilder<DocumentSnapshot>(
                stream: database.getTodos(),
                builder: (BuildContext context,
                    AsyncSnapshot<DocumentSnapshot> snapshot) {
                  if (!snapshot.hasData) {
                    return Center(child: CircularProgressIndicator());
                  } else {
                    // resolve stream... Stream<DocumentSnapshot> -> DocumentSnapshot -> Map<String, bool>
                    Map<String, dynamic> items = snapshot.data.data;

                    return ListView.builder(
                        itemCount: items.length,
                        itemBuilder: (context, i) {
                          String key = items.keys.elementAt(i);
                          return ToDoItem(
                            key,
                            items[key],
                            () => deleteItem(key),
                            () => toggleDone(key, items[key]),
                          );
                        });
                  }
                },
              );
            }
          }),
      floatingActionButton: FloatingActionButton(
        onPressed: newEntry,
        child: Icon(Icons.add),
        backgroundColor: Color.fromRGBO(35, 152, 185, 100),
      ),
    );
  }
}

依赖项：

  flutter:
    sdk: flutter


  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.3

  # Social sharing buttons
  share: '>=0.6.5 <2.0.0'


  # Google Firestore packages
  cloud_firestore: ^0.14.0+2
  firebase_auth: ^0.18.0+1

我尝试将其放入曲括号和圆括号中，但似乎这里存在更深的问题。感谢每一次帮助理解问题！

- Skyrockr

Answer 1

我对 Firestore 不太了解，但看了一下 API 文档，你需要使用 SetOption 类来进行合并：

 Future setTodo(String key, bool value) async {
    return await userToDos.doc(userID).set({key: value}, SetOptions(merge: true));
  }

- Ali Qanbari