Question

我是 flutter 的新手，我正在尝试在未来构建器中的列表视图构建器中调用 api 数据。但是我在快照中得到了空数据。

我的代码如下：

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:shared_preferences/shared_preferences.dart';



String token;

SharedPreferences sharedPreferences;

class ContinueW extends StatefulWidget {
  @override

  _ContinueWState createState() => _ContinueWState();
}

class _ContinueWState extends State<ContinueW> {


  Future getTokenValue() async {

    SharedPreferences espf = await SharedPreferences.getInstance();

    token = espf.getString('tokenvalue');

    return token;

  }

  Future createUser() async {

    String url ='http://3.137.182.252:8000/continue-watching';
    print('token');

    Map<String, String> headers = {
      'token': token,
    };
     await http.get(url, headers: headers).then((response){
      print('Entered');
      //print(response.body);
      var jre= jsonDecode(response.body);
      return jre;
     });


  }

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      body: Center(

        child: FutureBuilder(

          future: getTokenValue(),
          builder: (BuildContext context,snapshot){
            if(snapshot.hasData){
              return cbuild();

            } else{
              return CircularProgressIndicator();
            }
          },
        ),
      ),

    );
  }
  Widget cbuild(){

    return new FutureBuilder(

      future: createUser(),

    builder: (BuildContext context,snapshot) {

        if(snapshot.hasData) {
          return ListView.builder(
            itemBuilder: (context, index) {

              return ListTile(
                leading: CircleAvatar(
                  backgroundImage: snapshot.data['thumburl'] != null
                      ? NetworkImage(snapshot.data['thumburl'])
                     : Container(),),
                title: Text(snapshot.data[index]['name']),
                subtitle: Text(snapshot.data[index]['description']),
              );
            },
          );
        }
        else{
          return CircularProgressIndicator();
        }
    }
    );
  }
}

Answer 1

ListTile(
        leading: CircleAvatar(
          backgroundImage: snapshot.data[index]['thumburl'] != null
              ? NetworkImage(snapshot.data[index]['thumburl'])
             : Container(),),
        title: Text(snapshot.data[index]['name']),
        subtitle: Text(snapshot.data[index]['description']),
      );

根据您提供的详细信息。你可能会用 ['thumburl'] 丢失 [index]，

如果还是不行，那么你需要提供JSON格式的数据

Snapshot.data 为 null 。方法 [] 在 null 上被调用

1 个答案: