遍历 JSON 个对象并通过独特的深层属性对值求和

Question

下面是我的 JSON 对象（下面只是我感兴趣的值的例子，实际上除了成本还有很多其他参数）我正在尝试在 experss js 中使用下划线

[
    {   
        "Cost":250,
        "author": { id :"2", name : "Joe" , workId: "5" }
    },
    {   
        "Cost":450,
        "author": { id :"2", name : "Joe" , workId: "6" }
    },
    {   
        "Cost":150,
        "author": { id :"3", name : "Tam" , workId: "7" }
    },
    {   
        "Cost":250,
        "author": { id :"2", name : "Joe" , workId: "8" }
    },
    {   
        "Cost":350,
        "author": { id :"3", name : "Tam" , workId: "9" }
    }
]

我想要如下输出

Joe 950
Tam 500

我试过这个：

var iw={};
iw = Object.keys(myJsonObject.reduce((iw, curr) => {
    //iw[curr.author.id] = iw[curr.author.id]
    iw[curr.author.id].cost += parseInt(curr.cost);
    return iw;
}, iw)).map(key => iw[key]);
console.log("New ::"+iw);

但我没有得到我所希望的：

TypeError: Cannot read property 'cost' of undefined
    at Object.keys.myJsonObject.reduce (repl:3:7)
    at Array.reduce (<anonymous>)
New ::[object Object]

Answer 1

这可能是一种更简洁的方法，但是一个简单的 forEach 就可以了。显然这里输出的是一个对象，里面包含了想要的结果。

const data = [
    {   
        "Cost":250,
        "author": { id :"2", name : "Joe" , workId: "5" }
    },
    {   
        "Cost":450,
        "author": { id :"2", name : "Joe" , workId: "6" }
    },
    {   
        "Cost":150,
        "author": { id :"3", name : "Tam" , workId: "7" }
    },
    {   
        "Cost":250,
        "author": { id :"2", name : "Joe" , workId: "8" }
    },
    {   
        "Cost":350,
        "author": { id :"3", name : "Tam" , workId: "9" }
    }
]

let a = {};

data.forEach(e => a[e.author.name] ? a[e.author.name] += e.Cost : a[e.author.name] = e.Cost);

console.log(a);

Answer 2

如Fraser所述

您的原始代码存在问题，无法检查该用户是否已经存在于 iw 对象中

您更正的解决方案：

myJsonObject = 
[
    {   
        "Cost":250,
        "author": { id :"2", name : "Joe" , workId: "5" }
    },
    {   
        "Cost":450,
        "author": { id :"2", name : "Joe" , workId: "6" }
    },
    {   
        "Cost":150,
        "author": { id :"3", name : "Tam" , workId: "7" }
    },
    {   
        "Cost":250,
        "author": { id :"2", name : "Joe" , workId: "8" }
    },
    {   
        "Cost":350,
        "author": { id :"3", name : "Tam" , workId: "9" }
    }
]

var iw={};
iw = myJsonObject.reduce((iw, curr) => {
iw[curr.author.name] ? iw[curr.author.name] += curr.Cost : iw[curr.author.name] = curr.Cost;
    return iw;
}, iw);

console.log(iw);

结果：

{Joe: 950, Tam: 500}

遍历 JSON 个对象并通过独特的深层属性对值求和

Loop through JSON object and sum values by unique deep properties

javascript

express

underscore.js