javascript - 基于id的Javascript过滤器

在我的图表中，我有三种实体。
省，区和市。

关系是市属于区，区属于省。

这是我的数据库表
区域。

id | region_name      | region_parent_id
1  | Western province | null
2  | Colombo          | 1
3  | Gampaha          | 1
4  | Kaluthara        | 1
5  | Nugegoda         | 2
6  | Maharagama       | 2
7  | Central province | null
8  | Kandy            | 7
9  | Mathale          | 7
10 | theldeniya       | 8
11 | penideniya       | 8

如果我得出关系，我会是这样，

西部省

科伦坡

  Nugegoda
  Maharagama

甘帕哈

卡卢塔拉

中央省

康提

Theldeniya
Penideniya

Mathale

我得到的数据是这样的对象数组，

const regions = [
{id:1,region_name:"Western province",region_parent_id:null},
{id:2,region_name:"Colombo",region_parent_id:1},
{id:3,region_name:"Gampaha",region_parent_id:1},
{id:4,region_name:"Kaluthara",region_parent_id:1},
{id:5,region_name:"Nugegoda",region_parent_id:2},
{id:6,region_name:"Maharagama",region_parent_id:2},
{id:7,region_name:"Central province",region_parent_id:null},
{id:8,region_name:"Kandy",region_parent_id:7},
{id:9,region_name:"Mathale",region_parent_id:7},
{id:10,region_name:"theldeniya",region_parent_id:8},
{id:11,region_name:"penideniya",region_parent_id:8}

]

console.log(regions.filter(e=> !e.region_parent_id ))

我可以很容易地得到像这样的省。

console.log(regions.filter(e=> !e.region_parent_id ))

但是，如何获得地区列表和城市列表？

最佳答案

尝试这个：

var parId = prompt("Enter region parent id : " ) ;

const regions = [
  {id:1,region_name:"Western province",region_parent_id:null},
  {id:2,region_name:"Colombo",region_parent_id:1},
  {id:3,region_name:"Gampaha",region_parent_id:1},
  {id:4,region_name:"Kaluthara",region_parent_id:1},
  {id:5,region_name:"Nugegoda",region_parent_id:2},
  {id:6,region_name:"Maharagama",region_parent_id:2},
  {id:7,region_name:"Central province",region_parent_id:null},
  {id:8,region_name:"Kandy",region_parent_id:7},
  {id:9,region_name:"Mathale",region_parent_id:7},
  {id:10,region_name:"theldeniya",region_parent_id:8},
  {id:11,region_name:"penideniya",region_parent_id:8}
]

function belong(dis) {
  var getProvince = regions.find( e => e.id === dis ) ;
  if ( getProvince ) {
    console.log("==========" + getProvince.region_name + "==========" ) ;
    regions.map( c => {if (c.region_parent_id === dis ) console.log(c.region_name + " " + c.id +" Parent:(" + c.region_parent_id +")") } )
  }
}

belong( parseInt(parId) );

关于javascript - 基于id的Javascript过滤器，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/54016124/