Nested object reduce group by and sum - javascript

Question

I have a json object with data, I need to group these by name, sum the weight by name, and sum the grades. I have been trying for 2 days now. It should look like {name,weightTotal,grade{grade1total:, grade2total, grade2total}}... i looked through about 30 stack qs and tried reducing and foreach groupby and I don't understand any of it, I'm a 3rd year student doing my first internship. Need this to progress on the frontend to display these as a table. These are from rest endpoint btw.

Data

"data": [
    {
      name: "france Naicin",
      avgTotalWeight: 16,
      grade: {
        grade1: 16,
        grade2: 0,
        grade3: 0,
      },
    },
    {
      name: "pacific gigas",
      avgTotalWeight: 16,
      grade: {
        grade1: 16,
        grade2: 0,
        grade3: 0,
      },
    },
    {
      name: "france Naicin",
      avgTotalWeight: 13,
      grade: {
        grade1: 13,
        grade2: 0,
        grade3: 0,
      },
    },
    {
      name: "france Naicin",
      avgTotalWeight: 14,
      grade: {
        grade1: 14,
        grade2: 0,
        grade3: 0,
      },
    },
    {
      name: "france Naicin",
      avgTotalWeight: 15,
      grade: {
        grade1: 15,
        grade2: 0,
        grade3: 0,
      },
    },
  ],

My code to get this json:

let a = [];

    for (let i = 0; i <= data.length; i++) {
      if (!data[i]) {
        continue;
      }

      const {avgTotalWeight} = data[i];
      const {name} = data[i].truerun.batch.shellfish;
      const {alias} = data[i].truerun.grade_list;
      const {updatedAt} = data[i];
      const {isExist} = data[i].truerun;

      if (avgTotalWeight !== null) {
        let grade1,
          grade2,
          grade3 = 0;

        if (alias === "G1") {
          grade1 = avgTotalWeight;
        } else grade1 = 0;

        if (alias === "G2") {
          grade2 = avgTotalWeight;
        } else grade2 = 0;

        if (alias === "G3") {
          grade3 = avgTotalWeight;
        } else grade3 = 0;

        let b = {
          name: name,
          avgTotalWeight: avgTotalWeight,
          //updatedAt: updatedAt,
          //isExist: isExist,
          grade: {
            grade1: grade1,
            grade2: grade2,
            grade3: grade3,
          },
        };

        a.push(b);
      }
    }

    return a;

{ "name": "france Naicin", "avgTotalWeight": 36, "grade": { "grade1": 16, "grade2": 10, "grade3": 10 } }, { "name": "pacific gigas", "avgTotalWeight": 46, "grade": { "grade1": 16, "grade2": 10, "grade3": 20 } }, — Michal Kubiak, May 20 '21 at 15:01
sorry for the formatting, but just totals under different names so grouped by names, total weight of them, and total weight of each grades — Michal Kubiak, May 20 '21 at 15:02
How `france Naicin`'s `avgTotalWeight` is `36`. Is it not should be `58` — DecPK, May 20 '21 at 15:03
yea sorry there is more entries in the data I just scooped the first few objects, it should just be the total whatever the total should be! — Michal Kubiak, May 20 '21 at 15:05

DecPK · Accepted Answer · 2021-05-20T15:14:50.557

0

You can easily achieve this result using reduce

If some case grade key increases then you can add dynamic code so that it can work with infinite keys in grade. Just replace

isExist.grade.grade1 += grade.grade1;
isExist.grade.grade2 += grade.grade2;
isExist.grade.grade3 += grade.grade3;

with

Object.keys(isExist.grade).forEach((key) => {
  isExist.grade[key] += curr.grade[key];
});

const obj = {
  data: [
    {
      name: "france Naicin",
      avgTotalWeight: 16,
      grade: {
        grade1: 16,
        grade2: 0,
        grade3: 0,
      },
    },
    {
      name: "pacific gigas",
      avgTotalWeight: 16,
      grade: {
        grade1: 16,
        grade2: 0,
        grade3: 0,
      },
    },
    {
      name: "france Naicin",
      avgTotalWeight: 13,
      grade: {
        grade1: 13,
        grade2: 0,
        grade3: 0,
      },
    },
    {
      name: "france Naicin",
      avgTotalWeight: 14,
      grade: {
        grade1: 14,
        grade2: 0,
        grade3: 0,
      },
    },
    {
      name: "france Naicin",
      avgTotalWeight: 15,
      grade: {
        grade1: 15,
        grade2: 0,
        grade3: 0,
      },
    },
  ],
};

const result = obj.data.reduce((acc, curr) => {
  const { name, avgTotalWeight, grade } = curr;
  const isExist = acc.find((o) => o.name === name);
  if (isExist) {
    isExist.weightTotal += avgTotalWeight;
    isExist.grade.grade1 += grade.grade1;
    isExist.grade.grade2 += grade.grade2;
    isExist.grade.grade3 += grade.grade3;
  } else {
    acc.push({
      name,
      weightTotal: avgTotalWeight,
      grade,
    });
  }
  return acc;
}, []);

console.log(result);

edited May 20 '21 at 15:14

answered May 20 '21 at 15:06

DecPK

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Is this what you want? – DecPK May 20 '21 at 15:06
Added `weightTotal` of same person and individual `grade` also. – DecPK May 20 '21 at 15:07
thanks thats a start, the weight is summed up correctly, the grades ar enot however, not sure why, there are grade 2 and grade 3 ones there and I'm just getting 8000 grade 1 for the first name :/ – Michal Kubiak May 20 '21 at 15:09
so the weight is summed correctly grouped by name, the grades are wrong unfortunatley – Michal Kubiak May 20 '21 at 15:10
updating code... – DecPK May 20 '21 at 15:10
updated code, Please verify Is this what you want... – DecPK May 20 '21 at 15:12
1

it worked!! thanks so much ill be sure to study it so I understand it, thanks a million I'm not sure how to support you for this answer ! – Michal Kubiak May 20 '21 at 15:13
cannot thank you enough – Michal Kubiak May 20 '21 at 15:14

Nested object reduce group by and sum - javascript

1 Answers1