在颤振中使用列表视图搜索数据时出错

Posted 2023-02-23

【中文标题】在颤振中使用列表视图搜索数据时出错

【英文标题】：Error in searching data using listview in flutter

【发布时间】：2021-10-18 09:14:38

【问题描述】：

我已尝试使用此代码在列表视图中搜索工作，但数据未显示在列表视图中。我认为 JSON 无法正确解析 Jobs 数据。

这是模型的代码：

import 'package:flutter/material.dart';

class JobItem 
  final String title;
  final String description;

  JobItem(
       
      required this.title,
        required this.description,
        );

  factory JobItem.fromJson(Map<String, dynamic> json) 
    return JobItem(
      title: json['title'] as String,
      description: json['description'] as String,
    );
  

这里我已经为主文件编写了代码来从列表视图中搜索数据。

 List<JobItem> users = [];
  List<JobItem> filteredUsers = [];
  static String url = 'https://hospitality92.com/api/jobsbycategory/All';

  static Future<List<JobItem>> getJobsData() async 
    try 
      final response = await http.get(Uri.parse(url));
      if (response.statusCode == 200) 
        List<JobItem> list = parseAgents(response.body);

        return list;
       else 
        throw Exception('Error');
      
     catch (e) 
      throw Exception(e.toString());
    
  
  static List<JobItem> parseAgents(String responseBody) 
    final parsed = json.decode(responseBody).cast<Map<String, dynamic>>();
    return parsed.map<JobItem>((json) => JobItem.fromJson(json)).toList();
  


  @override
  void initState() 
    super.initState();
    getJobsData().then((usersFromServer) 
      setState(() 
        users = usersFromServer;
        filteredUsers = users;
      );
    );
  ```


 

【问题讨论】：

你检查过getJobData()的值吗

【参考方案1】：

你在解析时有一点错误。我加了response.body['jobs']。

static Future<List<JobItem>> getJobsData() async 
try 
  final response = await http.get(Uri.parse(url));
  if (response.statusCode == 200) 
    List<JobItem> list = parseAgents(Map<String, dynamic>.from(jsonDecode(response.body))['jobs']);

    return list;
   else 
    throw Exception('Error');
  
 catch (e) 
  throw Exception(e.toString());
 

【讨论】：

先生出现以下错误。 ** 不能将“String”类型的值分配给“int”类型的变量。 List list = parseAgents(response.body['jobs']); **

我稍微改变了函数。现在就试试吧！

【参考方案2】：

试试下面的代码你的问题已经解决了：

//declare packages
import 'dart:convert';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:http/http.dart' as http;

class Jobs extends StatefulWidget 
  Jobs() : super();

  @override
  JobsState createState() => JobsState();


class Debouncer 
  final int milliseconds;
  VoidCallback action;
  Timer _timer;

  Debouncer(this.milliseconds);

  run(VoidCallback action) 
    if (null != _timer) 
      _timer.cancel();
    
    _timer = Timer(Duration(milliseconds: milliseconds), action);
  


class JobsState extends State<Jobs> 
  final _debouncer = Debouncer(milliseconds: 500);

  List<Subject> subjects = [];
  List<Subject> filteredSubjects = [];
  //API call for All Subject List

  static String url = 'https://hospitality92.com/api/jobsbycategory/All';

  static Future<List<Subject>> getAllSubjectsList() async 
    try 
    final response = await http.get(Uri.parse(url));

    if (response.statusCode == 200) 
      print(response.body);
      List<Subject> list = parseAgents(response.body);

      return list;
     else 
      throw Exception('Error');
    
     catch (e) 
      throw Exception(e.toString());
    
  

  static List<Subject> parseAgents(String responseBody) 
    final parsed =
        json.decode(responseBody)['jobs'].cast<Map<String, dynamic>>();
    return parsed.map<Subject>((json) => Subject.fromJson(json)).toList();
  

  @override
  void initState() 
    super.initState();
    getAllSubjectsList().then((subjectFromServer) 
      setState(() 
        subjects = subjectFromServer;
        filteredSubjects = subjects;
      );
    );
  

  //Main Widget
  @override
  Widget build(BuildContext context) 
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'All Subjects',
          style: TextStyle(fontSize: 25),
        ),
      ),
      body: Column(
        children: <Widget>[
          //Search Bar to List of typed Subject
          Container(
            padding: EdgeInsets.all(15),
            child: TextField(
              textInputAction: TextInputAction.search,
              decoration: InputDecoration(
                enabledBorder: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(25.0),
                  borderSide: BorderSide(
                    color: Colors.grey,
                  ),
                ),
                focusedBorder: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(20.0),
                  borderSide: BorderSide(
                    color: Colors.blue,
                  ),
                ),
                suffixIcon: InkWell(
                  child: Icon(Icons.search),
                ),
                contentPadding: EdgeInsets.all(15.0),
                hintText: 'Search ',
              ),
              onChanged: (string) 
                _debouncer.run(() 
                  setState(() 
                    filteredSubjects = subjects
                        .where((u) => (u.title
                            .toLowerCase()
                            .contains(string.toLowerCase())))
                        .toList();
                  );
                );
              ,
            ),
          ),
          //Lists of Subjects
          Expanded(
            child: ListView.builder(
              shrinkWrap: true,
              physics: ClampingScrollPhysics(),
              padding: EdgeInsets.only(top: 20, left: 20, right: 20),
              itemCount: filteredSubjects.length,
              itemBuilder: (BuildContext context, int index) 
                return Card(
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(20),
                    side: BorderSide(
                      color: Colors.grey[300],
                    ),
                  ),
                  child: Padding(
                    padding: EdgeInsets.all(5.0),
                    child: Column(
                      mainAxisAlignment: MainAxisAlignment.start,
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: <Widget>[
                        ListTile(
                          leading: Text(
                            filteredSubjects[index].skills,
                          ),
                          title: Text(
                            filteredSubjects[index].title,
                            style: TextStyle(fontSize: 16),
                          ),
                          trailing: Text(filteredSubjects[index].position.toString()),
                        )
                      ],
                    ),
                  ),
                );
              ,
            ),
          ),
        ],
      ),
    );
  


//Declare Subject class for json data or parameters of json string/data
//Class For Subject
  class Subject 
  String title;
  int id;
  String skills;
  String position;
  Subject(
    this.id,
    this.title,
    this.skills,
    this.position,
  );

  factory Subject.fromJson(Map<String, dynamic> json) 
    return Subject(
        title: json['title'] as String,
        id: json['id'],
        skills: json['skills'],
        position: json['positions']);
  

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