Flutter / Dart如何分组按地图列表 [英] Flutter/Dart how to groupBy list of maps

问题描述

我有此地图列表。

[
    {title: 'Avengers', release_date: '10/01/2019'},
    {title: 'Creed', release_date: '10/01/2019'}
    {title: 'Jumanji', release_date: '30/10/2019'},
]

我想编写一个将电影列表按 release_date 。

I would like to write a code that would group the list of movies by release_date like that.

[
   {
      "10/01/2019": [
         {
            "title": "Avengers"
         },
         {
            "title": "Creed"
         }
      ]
   },
   {
      "30/10/2019": [
         {
            "title": "Jumanji"
         }
      ]
   }
]

推荐答案

包收藏实现了
和 groupBy 函数。

按日期分组：

import "package:collection/collection.dart";

main(List<String> args) {
  var data = [
    {"title": 'Avengers', "release_date": '10/01/2019'},
    {"title": 'Creed', "release_date": '10/01/2019'},
    {"title": 'Jumanji', "release_date": '30/10/2019'},
  ];


  var newMap = groupBy(data, (obj) => obj['release_date']);

  print(newMap);
}

用于删除 release_date 每个映射项中的键：

For removing the release_date key from each map entry:

var newMap = groupBy(data, (obj) => obj['release_date']).map(
    (k, v) => MapEntry(k, v.map((item) { item.remove('release_date'); return item;}).toList()));

更改键：

var newMap = groupBy(data, (obj) => obj['release_date']).map(
    (k, v) => MapEntry(k, v.map((item) => {'name': item['title']}).toList()));

这篇关于Flutter / Dart如何分组按地图列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！