怎么使用 Lodash /Js 进行按对象字段分组处理

Question

json对象

[
    dictprovinceVOList[{
    areaId: 13257
    cityAreaList:[
    {
        areaCode: "1853"
        areaId: 13265
        areaList: 
        firstLetter:"S"
        langType:"zh_CN"
        latitude:22.124049
        longitude:
        113.559954
        parentId:13257
        pinYin:"shengfangjigetangqu"
        postCode:"820008"
        sortValue:8
        title:"圣方济各堂区"
    },
    {
        ...
    }]
    parentId: 0
    sortValue: 34
    title:"澳门特别行政区"
   },{
    areaId:13238
    cityAreaList:[
    {
        areaCode: "1853"
        areaId: 13265
        areaList: 
        firstLetter:"S"
        langType:"zh_CN"
        latitude:22.124049
        longitude:
        113.559954
        parentId:13257
        pinYin:"shengfangjigetangqu"
        postCode:"820008"
        sortValue:8
        title:"圣方济各堂区"
    },{
        ...
    }]
    parentId:0
    sortValue:33
    title:"香港特别行政区"
   }]


]

得到以下结果。。分组依据是cityAreaList字段：firstLetter

{
   "iniData":"S",
   "cityAreaList":[
        {
          "areaCode":"1853","areaId": 372, ...
        }，
        {...}
    ]
}

Answer 1

lodash应该没有一步到位的函数
但有个groupBy函数可以用来分组
你可以用一个循环把所有城市的cityAreaList合到一个array
let array = [];
for(let city of citylist){
array = array.contact(city.cityAreaList)
}
然后
_.groupBy(array,function(obj){
return obj["firstLetter"];
})
返回是一个object是大概是这种结构的
｛
s:[
{
"areaCode":"1853","areaId": 372, ...}，
{...}
]
p:{
...
}
｝
这个object的key就是你想要的"iniData"剩下的事情就简单了
用Object.keys()获取object的所以key
let keys = Object.keys(object);
let newArr = [];
for(let key of keys){
newArr.push(
{
"iniData":key,
"cityAreaList":object[key]
}
)
}
这个newArr就是你想要的结果