Question

我有一些数据如下：

var items = [
{   "id" : 1,
    "title" : "this",
    "groups" : [
        {"id" : 1,
        "name" : "groupA"},
        {"id" : 2,
        "name" : "groupB"}
    ]
},
{   "id" : 2,
    "title" : "that",
    "groups" : [
        {"id" : 1,
        "name" : "groupA"},
        {"id" : 3,
        "name" : "groupC"}
    ]
},
{   "id" : 3,
    "title" : "other",
    "groups" : [
        {"id" : 3,
        "name" : "groupC"},
        {"id" : 2,
        "name" : "groupB"}
    ]
}]

我想基于组ID进行过滤，但我甚至无法访问它们 - item.group返回整个对象并执行任何其他操作（即item.groups.id）返回null或未定义的值

任何有关如何做到这一点的帮助都会很棒。基本上我想过滤数组以包含特定组中的所有项目。

由于

Answer 1

试试这个：

map()

Answer 2

使用：

Array.prototype.map创建一个新数组，通过
使用spread operator *克隆每个项目，并使用

groups

Array.prototype.filter仅保留具有正确id。

*需要像babel或打字稿这样的转录程序

OR

如果你想展平结构，那么可以使用Array.prototype.reduce来组合数组。

以下代码有两个输出：

保留了原始结构，但过滤掉了不具有3 ID的群组中的项目。
一个扁平化结构并输出一个阵列。

＆＃13;

const items = [{
    "id": 1,
    "title": "this",
    "groups": [{
        "id": 1,
        "name": "groupA"
      },
      {
        "id": 2,
        "name": "groupB"
      }
    ]
  },
  {
    "id": 2,
    "title": "that",
    "groups": [{
        "id": 1,
        "name": "groupA"
      },
      {
        "id": 3,
        "name": "groupC"
      }
    ]
  },
  {
    "id": 3,
    "title": "other",
    "groups": [{
        "id": 3,
        "name": "groupC"
      },
      {
        "id": 2,
        "name": "groupB"
      }
    ]
  }
];

const filteredRemovingGroups = items.map(item => ({
   ...item,
   groups: item.groups.filter(subItem => subItem.id === 3)
}));

const filterAndFlatten = items.map(item =>
  item.groups.filter(subItem => subItem.id === 3)
).reduce((combinedArr, arr) => [...combinedArr, ...arr], [])

console.log('filteredRemovingGroups', filteredRemovingGroups);
console.log('filterAndFlatten', filterAndFlatten);

＆＃13;

Answer 3

你可以这样做

var items = [{
  "id": 1,
  "title": "this",
  "groups": [{
    "id": 1,
    "name": "groupA"
  }, {
    "id": 2,
    "name": "groupB"
  }]
}, {
  "id": 2,
  "title": "that",
  "groups": [{
    "id": 1,
    "name": "groupA"
  }, {
    "id": 3,
    "name": "groupC"
  }]
}, {
  "id": 3,
  "title": "other",
  "groups": [{
    "id": 3,
    "name": "groupC"
  }, {
    "id": 2,
    "name": "groupB"
  }]
}]

// A filter function to filter out the matched value
function filterArray(array, val) {
  return array.filter(function(elem) {
    return elem.id === val; // filtering by Id
  })
}

// first filtering the original items array, & will get the object where id is 1
var obj = filterArray(items, 1);
//the previous result will return an array,
//so doing obj[0] which will give the first index. 
//obj[0].groups will be an array again

var filterGroup = filterArray(obj[0].groups,1) // will be an array which contains the matched group

DEMO

过滤对象内对象上的JSON对象

3 个答案: