在AngularJS中对对象数组进行分组

Question

基于如下所示的数组:

var members = [
  {name: "john", team: 1},
  {name: "kevin", team: 1},
  {name: "rob", team: 2},
  {name: "matt", team: 2},
  {name: "clint", team: 3},
  {name: "will", team: 3}
];

我需要为每个团队创建一个无序列表.

可以直接用ngRepeat和过滤器完成吗？

或者更容易将数组重新组织成一个包含成员列表的团队数组？

var teams = [
  {id: 1, members: ["john", "kevin"]},
  {id: 2, members: ["rob", "matt"]},
  {id: 3, members: ["clint", "will"]}
]

嵌套的ngRepeat很容易实现,但是如何以简单/聪明的方式从第一个数组转到这个数组呢？

注意:该数组不是来自数据库,而是来自html表.所以它只是一个简单的成员列表.

function MyController() {
  this.members = [
    {name: "john", team: 1},
    {name: "kevin", team: 1},
    {name: "rob", team: 2},
    {name: "matt", team: 2},
    {name: "clint", team: 3},
    {name: "will", team: 3}
  ];
}

angular.module('app', []);
angular.module('app')
    .controller('MyController', MyController);

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.3/angular.min.js"></script>
<div ng-app="app">
  <div ng-controller="MyController as ctrl">
    <ul>
      <li ng-repeat="member in ctrl.members">{{ member.name }} - {{ member.team }}</li>
    </ul>
  </div>
</div>

Answer 1

你有group物品.为此,我使用reduce方法来创建一个如下所示的hash集合:

{
  "1": [
    "john",
    "kevin"
  ],
  "2": [
    "rob",
    "matt"
  ],
   "3": [
     "clint",
      "will"
   ]
}

reduce()方法对累加器和数组中的每个元素(从左到右)应用一个函数,将其减少为单个值.

以下步骤是针对map此集合的array.为此,您应该使用map方法.

map()方法创建一个新数组,其结果是在此数组中的每个元素上调用提供的函数.

var members = [
  {name: "john", team: 1},
  {name: "kevin", team: 1},
  {name: "rob", team: 2},
  {name: "matt", team: 2},
  {name: "clint", team: 3},
  {name: "will", team: 3}
];
var groups = members.reduce(function(obj,item){
    obj[item.team] = obj[item.team] || [];
    obj[item.team].push(item.name);
    return obj;
}, {});
var myArray = Object.keys(groups).map(function(key){
    return {team: key, name: groups[key]};
});
console.log(myArray);

Answer 2

扩展了@ Alexandru-Ionut Mihai的答案,(只是为了体验一个reduce功能有多强大).这里是一个单一的,reduce没有map它再次实现同样的事情.:)

var members = [
  {name: "john", team: 1},
  {name: "kevin", team: 1},
  {name: "rob", team: 2},
  {name: "matt", team: 2},
  {name: "clint", team: 3},
  {name: "will", team: 3}
];
/*var teams = [
  {id: 1, members: ["john", "kevin"]},
  {id: 2, members: ["rob", "matt"]},
  {id: 3, members: ["clint", "will"]}
]*/
var group_to_values = members.reduce(function(arr, item){
    arr[item.team - 1] = arr[item.team - 1] || { id: item.team, members: []};
    arr[item.team - 1].members.push(item.name);
    return arr;
}, []);

console.log(group_to_values);