dart - 如何制作新数组嵌套排序映射

Posted 2021-10-31 Lucklyの博客

今天关注的人突然多了起来，为此继续更新今天的第二篇

dart - 如何制作新数组嵌套排序映射？

我有一个看起来像这样的数据块:

var list = [
  { id: '1', title: 'thing1', week: 1, day: 1 },
  { id: '2', title: 'thing2', week: 1, day: 1 },
  { id: '3', title: 'thing3', week: 1, day: 2 },
  { id: '4', title: 'thing4', week: 1, day: 2 },
  { id: '5', title: 'thing5', week: 1, day: 3 },
  { id: '6', title: 'thing6', week: 1, day: 3 },
  { id: '7', title: 'thing7', week: 2, day: 4 },
  { id: '8', title: 'thing8', week: 2, day: 5 },
];

我想要做的是将这个 List 转换为输出这个的东西:

var transformedList = [
  { 'Week 1': [
      { id: '1', title: 'thing1', day: 1, week: 1 },
      { id: '2', title: 'thing2', day: 1, week: 1 },
      { id: '3', title: 'thing3', day: 2, week: 1 },
      { id: '4', title: 'thing4', day: 2, week: 1 },
      { id: '5', title: 'thing5', day: 3, week: 1 },
      { id: '6', title: 'thing6', day: 3, week: 1 },
    ],
    'Week 2': [
      { id: '7', title: 'thing7', day: 4, week: 2 },
      { id: '8', title: 'thing8', day: 5, week: 3 },
    ]
  }
]

到目前为止我尝试过的是:

var programMap = Map.fromIterable(userProgramSteps, key: (k) => k.getWeek(), value: (v) => v);

// handles the week port just fine, but very stuck on the list of days.

我对flutter和 Dart 很陌生，所以我有点迷茫…有人可以帮忙吗？

最佳答案

尊重您之前(已删除)的问题，这里的代码:
data_weeks.dart

const week_data = [
  { 'id': '1', 'week': 1, 'day': 1, 'title': 'thing1' },
  { 'id': '2', 'week': 1, 'day': 1, 'title': 'thing2' },
  { 'id': '3', 'week': 1, 'day': 1, 'title': 'thing3' },
  { 'id': '4', 'week': 1, 'day': 2, 'title': 'thing4' },
  { 'id': '5', 'week': 1, 'day': 2, 'title': 'thing5' },
  { 'id': '6', 'week': 2, 'day': 3, 'title': 'thing6' },
  { 'id': '7', 'week': 2, 'day': 4, 'title': 'thing7' },
];

home_page.dart

import 'package:flutter/material.dart';
import 'package:list_cards/src/shared/data_weeks.dart';


class HomePage extends StatelessWidget {
  /* ---------------------------------------------------------------------------- */
  const HomePage({Key key}) : super(key: key);
  /* ---------------------------------------------------------------------------- */
  @override
  Widget build(BuildContext context) {
    final data = getNewData();

    return Scaffold(
      appBar: AppBar(
        title: Text('Hi!'),
        centerTitle: true,
      ),
      body: Padding(
        padding: const EdgeInsets.all(10.0),
        child: ListView.builder(
          itemCount: data.length,
          itemBuilder: (context, index) => ListTile(
            title: Text(
              'Week ${data.keys.toList()[index]}', 
              style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
            ),
            subtitle: getSubtitles1(data[data.keys.toList()[index]], context),
          ),
        ),
      ),
    );
  }

  Widget getSubtitles1(List<Map<int, Object>> data, BuildContext context) {
    return Column(
      children: List.generate(data.length, (index) => ListTile(
        title: Text(
          'DAY ${data[index].keys.toList()[0]}',
          style: TextStyle(
            fontSize: 18, fontWeight: FontWeight.bold, color: Colors.black.withOpacity(0.4)
          ),
        ),
        subtitle: getSubtitles2(data[index][data[index].keys.toList()[0]], context),
      )),
    );
  }

  Widget getSubtitles2(List<String> data, BuildContext context) {
    final size = MediaQuery.of(context).size;

    return Column(
      children: List.generate(data.length, (index) => Card(
        elevation: 0,
        margin: EdgeInsets.all(0),
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 2),
          child: Row(
            children: [
              Container(
                width: (size.width + 80) / 2,
                child: Text(data[index]),
              ),
              IconButton(icon: Icon(Icons.check_box_outline_blank), onPressed: () {}),
            ],
          ),
        ),
      )),
    );
  }

  Map<int, Object> getNewData() {
    var weeks = week_data.map<int>((m) => m['week']).toSet().toList();
    var newData = Map<int, Object>();

    weeks.forEach((w) {
      newData[w] = week_data.where((m) => m['week'] == w).map<int>((m) => m['day']).toSet().map<Map<int, Object>>((e) => {e: week_data.where((m) => m['week'] == w && m['day'] == e).map<String>((m) => m['title']).toList()}).toList();
    });

    return newData;
  }
}

结果:

关于您当前的问题，getNewData()方法包含您的答案的逻辑。好好享受!