Question

我想在我的 FutureBuilder 中返回一个字符串列表，但对我来说这是不可能的，因为一个错误告诉我列表不是 Widget 类型的子类型。实际上，返回必须是 List 类型才能将其添加到我的主类中的类中的列表的初始化中我将这两个类以及错误消息附加给您，以便您理解。谢谢

类READCITEE

import 'package:ampc93/fonction/firebase_crud/add_citee.dart';
import 'package:ampc93/fonction/firebase_crud/read_citee.dart';
import 'package:ampc93/page_citee.dart';
import 'package:flutter/material.dart';

class PageVille extends StatefulWidget {
  final String? titre;

  PageVille(this.titre);

  @override
  _PageVilleState createState() => _PageVilleState();
}

class _PageVilleState extends State<PageVille> {
  TextEditingController citeeController = TextEditingController();

  List<dynamic> citeesList = [];

  @override
  void initState() {
    super.initState();
    citeesList.add(ReadCitee(widget.titre!));
  }

  Future<void> displayDialog(BuildContext context) async {
    return showDialog(
        context: context,
        builder: (context) {
          return AlertDialog(
            content: TextField(
              controller: citeeController,
              textInputAction: TextInputAction.go,
              decoration:
                  InputDecoration(hintText: "Entrez une nouvelle citée"),
            ),
            actions: [
              TextButton(
                  child: Text("Ok"),
                  onPressed: () {
                    AddCitee(widget.titre!, citeeController.text);
                    setState(() {
                      citeesList.add(citeeController.text);
                      citeeController.clear();
                    });
                    Navigator.pop(context);
                  }),
              TextButton(
                onPressed: () {
                  Navigator.pop(context);
                  citeeController.clear();
                },
                child: Text("Annuler"),
              )
            ],
          );
        });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.titre!),
        backgroundColor: Colors.teal,
      ),
      body: Container(
          padding: EdgeInsets.all(20.0),
          child: ListView.separated(
              itemBuilder: (context, index) {
                return ListTile(
                    title: citeesList[index],
                    onTap: () => Navigator.push(
                        context,
                        MaterialPageRoute(
                            builder: (context) =>
                                PageCitee(citeesList[index]))),
                    trailing: IconButton(
                        icon: Icon(Icons.delete_forever),
                        color: Colors.red[300],
                        iconSize: 32,
                        onPressed: () {
                          setState(() {
                            citeesList.remove(citeesList[index]);
                          });
                        }));
              },
              separatorBuilder: (context, index) => Divider(),
              itemCount: citeesList.length)),
      floatingActionButton: FloatingActionButton(
        onPressed: () => displayDialog(context),
        child: Icon(Icons.add),
        backgroundColor: Colors.teal[300],
      ),
    );
  }
}

班级原则

The following _TypeError was thrown building FutureBuilder<DocumentSnapshot<Object?>>(dirty, state: _FutureBuilderState<DocumentSnapshot<Object?>>#b2e48):
type 'List<dynamic>' is not a subtype of type 'Widget'

The relevant error-causing widget was
FutureBuilder<DocumentSnapshot<Object?>>
package:ampc93/…/firebase_crud/read_citee.dart:12
When the exception was thrown, this was the stack
#0      ReadCitee.build.<anonymous closure>
package:ampc93/…/firebase_crud/read_citee.dart:23
#1      _FutureBuilderState.build
package:flutter/…/widgets/async.dart:773
#2      StatefulElement.build
package:flutter/…/widgets/framework.dart:4612
#3      ComponentElement.performRebuild
package:flutter/…/widgets/framework.dart:4495
#4      StatefulElement.performRebuild
package:flutter/…/widgets/framework.dart:4667
...

错误

http://localhost:3001/register

Answer 1

尝试删除“DocumentSnapshot”。因为显然，“FutureBuilder”期待“DocumentSnapshot”数据类型。尝试从“Future Builder”中删除它，看看会发生什么。

在 FutureBuilder 中返回一个列表

1 个答案: