NodeJS -从多层对象数组中提取数据

I have the following JSON array :

我有以下JSON数组:

{
"list": [{
    "name": "Assignment",
    "id": 67,
    "template": 0,
    "children": [{
        "assignmentnumber": 1000,
        "fromCountry": "Sweden",
        "toCountry": "Spain",
        "fromCity": "Stockholm",
        "toCity": "Madrid"
    }, {
        "assignmentnumber": 15678,
        "fromCountry": "Sweden",
        "toCountry": "Germany",
        "fromCity": "Stockholm",
        "toCity": "Berlin"
    }, {
        "assignmentnumber": 10001,
        "fromCountry": "Sweden",
        "toCountry": "United Kingdom",
        "fromCity": "Stockholm",
        "toCity": "London"
    }]
}, {
    "name": "Valuation form",
    "id": 36,
    "template": 0,
    "children": [15678]
}, {
    "name": "Claim",
    "id": 12,
    "template": 0,
    "children": [1000, 10001]
}]
}

I need to extract a new array from the array containing only the 'name' element. I have tried lodash but cannot figure out how to use it properly.

我需要从只包含“name”元素的数组中提取一个新的数组。我试过lodash，但不知道如何正确地使用它。

Anyone who can give me a clue how to do this ?

谁能告诉我怎么做这个?

3 个解决方案

#1

You should use map method, which accepts as parameter a callback function.

您应该使用map方法，它接受回调函数作为参数。

The map() method creates a new array with the results of calling a provided function on every element in this array.

map()方法创建一个新的数组，其结果是在这个数组中的每个元素上调用提供的函数。

var array=obj.list.map(callback);
function callback(item){
    return item.name;
}

Or simply:

或者仅仅是:

var array=obj.list.map(el=>el.name);

var obj={
"list": [{
    "name": "Assignment",
    "id": 67,
    "template": 0,
    "children": [{
        "assignmentnumber": 1000,
        "fromCountry": "Sweden",
        "toCountry": "Spain",
        "fromCity": "Stockholm",
        "toCity": "Madrid"
    }, {
        "assignmentnumber": 15678,
        "fromCountry": "Sweden",
        "toCountry": "Germany",
        "fromCity": "Stockholm",
        "toCity": "Berlin"
    }, {
        "assignmentnumber": 10001,
        "fromCountry": "Sweden",
        "toCountry": "United Kingdom",
        "fromCity": "Stockholm",
        "toCity": "London"
    }]
}, {
    "name": "Valuation form",
    "id": 36,
    "template": 0,
    "children": [15678]
}, {
    "name": "Claim",
    "id": 12,
    "template": 0,
    "children": [1000, 10001]
}]
};
console.log(obj.list.map(function(item){
    return item.name;
}));

#2

You can do this without lodash, using native Array APIs.

使用本机数组api，无需使用lodash，也可以这样做。

const obj = { /* The JSON in your question */ };
const names = obj.list.map(item => item.name);

Array.map() takes a function and calls that function on each item of an array, returning a new array containing the result of each item.

map()获取一个函数，并在数组的每个项上调用该函数，返回包含每个项结果的新数组。

#3

Map is the best way to go as everyone else stated. Another alternative is use a forEach loop, specially if you want to operate with them.

地图是大家都说的最好的方式。另一种选择是使用forEach循环，特别是如果您想使用它们。

var children = obj.children;
var array_of_names;

children.forEach(function (item)){
    array_of_names.push(item.name);
    //... Do more operations for each item
}

#1