jsonpath中数组的总和

Question

我正在尝试使用 sum() 函数。我已经浏览了Functions min(), max() or sum() with jsonpath 链接，但这并不能帮助我解决问题。我试图在https://jsonpath.herokuapp.com/ 上运行表达式，这给了我 $..price 的结果，其中包含年龄数组，但是当我想要像 $..price 这样的年龄总和时。 sum() 这给了我一个错误聚合函数试图使用空数组计算值。请你帮我写下正则表达式以获得年龄的总和。

Answer 1

安装包： https://www.npmjs.com/package/jsonpath

然后使用method reduce，试试：

var jp = require('jsonpath');

var data = {
    "store": {
        "book": [
            {
                "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
                "price": 8.95
            },
            {
                "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
                "price": 12.99
            },
            {
                "category": "fiction",
                "author": "Herman Melville",
                "title": "Moby Dick",
                "isbn": "0-553-21311-3",
                "price": 8.99
            },
            {
                "category": "fiction",
                "author": "J. R. R. Tolkien",
                "title": "The Lord of the Rings",
                "isbn": "0-395-19395-8",
                "price": 22.99
            }
        ],
        "bicycle": {
            "color": "red",
            "price": 19.95
        }
    },
    "expensive": 10
}

let sum = jp.query( data , '$..price' ).reduce( (acc,ele) => acc += ele ,0);

console.log(sum);