如何读取值并通过动态数组求和？

Question

I have an JSON like this

"result": [{
        "channel": "A",
        "mkp": "ABC",
        "qtd": 6,
        "total": 2938.2,
        "data": "2019-02-16",
        "time": "22:30:40"
    }, {
        "channel": "C",
        "mkp": "DEF",
        "qtd": 1545,
        "total": 2127229.64,
        "data": "2019-02-20",
        "time": "17:19:49"
    }, {
        "channel": "C",
        "mkp": "JKL",
        "qtd": 976,
        "total": 1307328.37,
        "data": "2019-02-20",
        "time": "17:19:53"
    }, {
        "channel": "U",
        "mkp": "PQR",
        "qtd": 77,
        "total": 98789.87,
        "data": "2019-02-20",
        "time": "16:12:31"
    }, {
        "channel": "U",
        "mkp": "STU",
        "qtd": 427,
        "total": 433206.62,
        "data": "2019-02-20",
        "time": "17:04:27"
    }
]

I need to sum the QTD, the total and return the newest data + time when the channel is the same (eg.: Channel C and U have 2 entries), if it's not so I only will display the values, but I can't figure it out how could I iterate and do these math. Someone could help?

A sample of what I want:

"A": [{
  "qtd": 6,
  "total": 2938.20,
  "dateTime": 2019 - 02 - 16 22: 30: 40 "
}],
"C": [{
  "qtd": 2.521,
  "total": 3434558.01,
  "dateTime": 2019 - 02 - 20 17: 19: 53 "
}],
"U": [{
  "qtd": 504,
  "total": 531996,
  49,
  "dateTime": 2019 - 02 - 20 17: 04: 27 "
}]

Currently I separated the values using filter like this:

this.channelA = this.receivedJson.filter(({ channel }) => channel === "A");

Answer 1

You could use reduce method and return one object with object as values.

 const data = [{"channel":"A","mkp":"ABC","qtd":6,"total":2938.2,"data":"2019-02-16","time":"22:30:40"},{"channel":"C","mkp":"DEF","qtd":1545,"total":2127229.64,"data":"2019-02-20","time":"17:19:49"},{"channel":"C","mkp":"JKL","qtd":976,"total":1307328.37,"data":"2019-02-20","time":"17:19:53"},{"channel":"U","mkp":"PQR","qtd":77,"total":98789.87,"data":"2019-02-20","time":"16:12:31"},{"channel":"U","mkp":"STU","qtd":427,"total":433206.62,"data":"2019-02-20","time":"17:04:27"}] const res = data.reduce((r, {channel, qtd, total, data, time}) => { const dateTime = `${data} ${time}` if(!r[channel]) r[channel] = {qtd, total, dateTime} else { r[channel].total += total r[channel].qtd += qtd; r[channel].dateTime = dateTime } return r; }, {}) console.log(res) 

Answer 2

You an use reduce to group the values based on channel like this:

 const input = [{"channel":"A","mkp":"ABC","qtd":6,"total":2938.2,"data":"2019-02-16","time":"22:30:40"},{"channel":"C","mkp":"DEF","qtd":1545,"total":2127229.64,"data":"2019-02-20","time":"17:19:49"},{"channel":"C","mkp":"JKL","qtd":976,"total":1307328.37,"data":"2019-02-20","time":"17:19:53"},{"channel":"U","mkp":"PQR","qtd":77,"total":98789.87,"data":"2019-02-20","time":"16:12:31"},{"channel":"U","mkp":"STU","qtd":427,"total":433206.62,"data":"2019-02-20","time":"17:04:27"}] const merged = input.reduce((acc, { channel, qtd, total, data, time }) => { acc[channel] = acc[channel] || [{ qtd: 0, total: 0, dateTime:'' }]; const group = acc[channel][0]; group.qtd += qtd; group.total += total; const dateTime = `${data} ${time}` if(dateTime > group.dateTime) group.dateTime = dateTime; return acc; }, {}) console.log(merged)