我是新来的，这个错误正在给我带来严重的噩梦。我有一张卡片清单，称为“锚点”。这些项目来自属于已登录用户的共享首选项文件。在共享首选项Json文件中，每个锚点都嵌套有一个或多个分发中心。全部以JSON形式存储在共享首选项中。现在，我能够在第一个屏幕上分别迭代锚点，但是我面临的挑战是，当我单击“查看锚点细节”按钮时，而不是带我进入详细信息页面，在该页面上我可以查看该锚点的细节并进行迭代它不是该锚点的分布中心，而是将整个锚点都放置在那里。我尝试仅将一个ID解析到详细信息页面，以便可以迭代该锚点的嵌套对象，但仍然无法正常工作。 类型’int’不是类型’List’的子类型， 但是如果我从详细信息屏幕的链接中删除 [i] [‘Oid’] ，它将在此处存储所有数据。它们都在两个不同的屏幕上。有人可以帮我吗？
JSON格式：
"Anchors": [ { "Oid": 11, "Name": "MAIZE ASSOCIATION OF NIGERIA", "Acronym": "MAAN", "DistributionCentres": [ { "Oid": 11, "Name": "Logo Centre (Zone A)", "Address": "Private Warehouse, Ugba, Logo LGA" }, { "Oid": 12, "Name": "Makurdi Centre (Zone B)", "Address": "Ministry of Agric, Makurdi " }, { "Oid": 13, "Name": "Oturkpo Centre (Zone C)", "Address": "Private Warehouse, Oturkpo" }, { "Oid": 15, "Name": "Borno MAAN centre", "Address": "Bolori Store, Flavour Mill, Behind Vita Foam, Maiduguri" }, { "Oid": 18, "Name": "Bauchi Centre", "Address": "BASPD, Dass Road, Bauchi" } ], "NoOfDistributionCentres": 5 }, { "Oid": 2, "Name": "MAIZE GROWERS, PROCESSORS AND MARKETERS ASSOCIATION OF NIGERIA", "Acronym": "MAGPAMAN", "DistributionCentres": [ { "Oid": 2, "Name": "Guma Centre", "Address": "P 32, 2nd Avenue Federal Housing Estate, N/Bank, Makurdi" }, { "Oid": 3, "Name": "Logo Centre", "Address": "Terhemen Akema Storage Facility, Ugba, Logo LGA" }, { "Oid": 5, "Name": "Oturkpo Centre", "Address": "Grain Store, Lower Benue Okele Project, Otukpo" }, { "Oid": 6, "Name": "Gboko Centre", "Address": "K3 New Road, Opposite former coca cola plant. Solar Schools Street, Gboko" }, { "Oid": 7, "Name": "Gwer East Centre", "Address": "Ahua Shardye's Warehouse, Behind Sylkan Filling Station, Ikpayongo , G/East LGA" }, { "Oid": 8, "Name": "Kwande Centre", "Address": "KM 3, Adagi Road, Adikpo" }, { "Oid": 9, "Name": "Ohimini Centre", "Address": "Ajoga Oglewu, Ohimini" }, { "Oid": 10, "Name": "Oju Centre", "Address": "Behind Town Hall, Ohuhu owo, Oju LGA" } ], "NoOfDistributionCentres": 8 } ],
锚页面：
import 'package:erg_app/Details.dart'; import 'package:flutter/material.dart'; import 'package:erg_app/Widgets/nav-drawer.dart'; import 'dart:convert'; import 'package:shared_preferences/shared_preferences.dart'; void main() => runApp(MaterialApp( home: AnchorsPage(), )); class AnchorsPage extends StatefulWidget { @override _MyHomeState createState() => _MyHomeState(); } List<Anchor> _parseAnchors(Map<String, dynamic> map) { final anchors = <Anchor>[]; for (var anchorMap in map['Anchors']) { final anchor = Anchor.fromMap(anchorMap); anchors.add(anchor); } return anchors; } class Anchor { final int oId; final String name; final String acronym; final List<DistributionCenter> distributionCenters; const Anchor({ @required this.oId, @required this.name, @required this.acronym, @required this.distributionCenters, }); factory Anchor.fromMap(Map<String, dynamic> map) { final distributionCenters = <DistributionCenter>[]; for (var distribution in map['DistributionCentres']) { final distributionCenter = DistributionCenter.fromMap(distribution); distributionCenters.add(distributionCenter); } return Anchor( oId: map['Oid'] as int, name: map['Name'] as String, acronym: map['Acronym'] as String, distributionCenters: distributionCenters, ); } } class DistributionCenter { final int id; final String name; final String address; const DistributionCenter({ @required this.id, @required this.name, @required this.address, }); factory DistributionCenter.fromMap(Map<String, dynamic> map) { return DistributionCenter( id: map['Oid'] as int, name: map['Name'] as String, address: map['Address'] as String, ); } } class _MyHomeState extends State<AnchorsPage> { var user; var userData; List anchors = []; @override void initState() { _getUserAnchor(); super.initState(); } _getUserAnchor() async { SharedPreferences localStorage = await SharedPreferences.getInstance(); var userJson = localStorage.getString('loginRes'); user = json.decode(userJson); setState(() { anchors = user['Anchors']; }); print(anchors); setState(() { userData = anchors; }); } @override Widget build(BuildContext context) { return Scaffold( drawer: NavDrawer(), appBar: AppBar( title: Text('Anchors Details'), iconTheme: IconThemeData(color: Colors.white), backgroundColor: Colors.green, ), body: Container( padding: const EdgeInsets.fromLTRB(10, 30, 10, 10), child: ListView( children: <Widget>[ Row( mainAxisAlignment: MainAxisAlignment.spaceAround, children: <Widget>[ Icon(Icons.card_membership, size: 35, color: Colors.orange[400]), Text( 'Assigned Anchors', style: TextStyle(color: Colors.orange[400], fontSize: 25), ), ], ), ListView.builder( shrinkWrap: true, itemCount: anchors.length, physics: NeverScrollableScrollPhysics(), itemBuilder: (BuildContext context, int i) { return Padding( padding: const EdgeInsets.all(10.0), ////////////// 1st card/////////// child: Card( elevation: 4.0, color: Colors.grey[100], margin: EdgeInsets.only( left: 10, right: 10, top: 20, bottom: 10), shape: RoundedRectangleBorder( borderRadius: BorderRadius.circular(10)), child: Container( padding: EdgeInsets.only(left: 15, top: 20, bottom: 10), width: MediaQuery.of(context).size.width, child: Column( crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[ Row( children: <Widget>[ Padding( padding: const EdgeInsets.all(8.0), child: Container( width: 50.0, height: 50.0, decoration: new BoxDecoration( shape: BoxShape.circle, image: new DecorationImage( fit: BoxFit.cover, image: AssetImage( 'assets/images/user.png')))), ), SizedBox( width: 20, ), Text( anchors[i]['Acronym'], textAlign: TextAlign.center, style: TextStyle( color: Color(0xFF9b9b9b), fontSize: 20, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ], ), Container(width: 10), Row( children: <Widget>[ Padding( padding: const EdgeInsets.only(left: 10, top: 10), child: Text( 'Allocated Farmers:', textAlign: TextAlign.left, style: TextStyle( color: Color(0xFF9b9b9b), fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), Padding( padding: const EdgeInsets.only(left: 70, top: 12), child: Text( anchors[i]['Oid'].toString(), textAlign: TextAlign.left, style: TextStyle( color: Colors.grey[700], fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), ], ), Row( children: <Widget>[ Padding( padding: const EdgeInsets.only(left: 10, top: 10), child: Text( 'Validated Farmers:', textAlign: TextAlign.left, style: TextStyle( color: Color(0xFF9b9b9b), fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), Padding( padding: const EdgeInsets.only(left: 70, top: 12), child: Text( anchors[i]['Oid'].toString(), textAlign: TextAlign.left, style: TextStyle( color: Colors.grey[700], fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), ], ), Row( children: <Widget>[ Padding( padding: const EdgeInsets.only(left: 10, top: 10), child: Text( 'Non Validated Farmers:', textAlign: TextAlign.left, style: TextStyle( color: Color(0xFF9b9b9b), fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), Padding( padding: const EdgeInsets.only(left: 40, top: 12), child: Text( anchors[i]['Oid'].toString(), textAlign: TextAlign.left, style: TextStyle( color: Colors.grey[700], fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), ], ), Row( children: <Widget>[ Padding( padding: const EdgeInsets.only(left: 10, top: 10), child: Text( 'Distribution Centers:', textAlign: TextAlign.left, style: TextStyle( color: Color(0xFF9b9b9b), fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), Padding( padding: const EdgeInsets.only(left: 60, top: 12), child: Text( anchors[i]['Oid'].toString(), textAlign: TextAlign.left, style: TextStyle( color: Colors.grey[700], fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), ], ), Row( children: <Widget>[ Padding( padding: const EdgeInsets.only(left: 10, top: 10), child: Text( 'Daily Inventory Status:', textAlign: TextAlign.left, style: TextStyle( color: Color(0xFF9b9b9b), fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), Padding( padding: const EdgeInsets.only(left: 50, top: 12), child: Text( '3', textAlign: TextAlign.left, style: TextStyle( color:Colors.green, fontSize: 14.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), ], ), Container( height: 20, ), Row( children: <Widget>[ /////////// Buttons ///////////// Padding( padding: const EdgeInsets.all(10.0), child: FlatButton( child: Padding( padding: EdgeInsets.only( top: 8, bottom: 8, left: 10, right: 8), child: Text( 'View Details', textDirection: TextDirection.ltr, style: TextStyle( color: Colors.white, fontSize: 15.0, decoration: TextDecoration.none, fontWeight: FontWeight.normal, ), ), ), color: Colors.blueGrey, shape: new RoundedRectangleBorder( borderRadius: new BorderRadius.circular( 20.0)), onPressed: () { Navigator.push( context, new MaterialPageRoute( builder: (context) => detailsPage(value : anchors[i]['Oid']))); }, ), ), /////////// End of Buttons ///////////// ], ), ], ), ), ), ); }) ], ), ), ); } }
详细信息页面：
import 'package:flutter/material.dart'; class detailsPage extends StatefulWidget { List value; detailsPage({Key key, @required this.value}) : super(key: key); @override _detailsPageState createState() => _detailsPageState(value); } class _detailsPageState extends State<detailsPage> { List value; _detailsPageState(this.value); @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text("Anchors Details Page"), iconTheme: IconThemeData(color: Colors.white), backgroundColor: Colors.green, ), body: Container( child: ListView( children: <Widget>[ Text(value[1]['Name']), Text(value[1]['Oid'].toString()), ListView.builder( shrinkWrap: true, itemCount: value[1]['DistributionCentres'].length, //context:context, //it saying the name parameter context is not defined physics: NeverScrollableScrollPhysics(), itemBuilder: (BuildContext context, int i) { return Text(value[1]['DistributionCentres'][i]['Name']); }) ], ), ), ); } }
我要实现的图像如下：
第一个屏幕onPressed获取索引并将其分配给变量，或者您也可以通过varibale，
onPressed: () { Navigator.push(context,new MaterialPageRoute(builder: (context) => detailsPage(i))); },
在详细页面
class detailsPage extends StatefulWidget { final int selectedIndex; detailsPage(this.selectedIndex,{Key key}) : super(key: key); @override _detailsPageState createState() => _detailsPageState(); }
您要使用上一页传递的索引的位置，
return Text(value[widget.selectedIndex]['DistributionCentres'][i]['Name']);
希望这会有所帮助。
