Combining JSON objects to form a new object within a JSON object using JavaScript

Question

Combining JSON objects to form a new object within a JSON object using JavaScript

Here is the JSON data that I have:

{"rows":[
    {"shiftId":1,"shift":"Morning","item":"Tea","value":20},
    {"shiftId":1,"shift":"Morning","item":"Coffee","value":30},
    {"shiftId":2,"shift":"Evening","item":"Tea","value":40},
    {"shiftId":2,"shift":"Evening","item":"Coffee","value":35}
]}

I want to merge entries with the same shift, add their values together, and create a new object for each item. The desired output should look like this:

{"rows":[
    {
     "shiftId":1,
     "shift":"Morning",
     "item":[{"itemName":"Tea"},{"itemName":"Coffee"}],
     "value":50
     },
    {
    "shiftId":2,
    "shift":"Evening",
    "item":[{"itemName":"Tea"},{"itemName":"Coffee"}],
    "value":75
    }
]}

I attempted to achieve this using the following code:

var merged = {rows: []};
data.forEach(function (source) {
    if (!merged.rows.some(function (row) {
        return row.shiftId == source.shiftId;
    })) {
        merged.rows.push({
            shiftId: source.shift,
            shift: source.shift,
            item: [{
                itemName: source.shift
            }],
            value: source.value
        });
    } else {
        var existRow = merged.rows.filter(function (existRow) {
            return existRow.shiftId == source.shiftId
        })[0];
        existRow.total += source.total;  // There was an error here, it should be "existRow.value += source.value"
        existRow.item = source.item.push(existRow.item);  
    }
});

However, this code is not functioning as expected. Thank you in advance for your help.

javascript json

Answer 1

Answer №1

A possible approach is to utilize a hash table to reference objects with the same shiftId, allowing for the creation of a new array containing the collected and grouped data.

var data = { rows: [{ shiftId: 1, shift: "Morning", item: "Tea", value: 20 }, { shiftId: 1, shift: "Morning", item: "Coffee", value: 30 }, { shiftId: 2, shift: "Evening", item: "Tea", value: 40 }, { shiftId: 2, shift: "Evening", item: "Coffee", value: 35 }] },
    result = {
        rows: data.rows.reduce(function (hash) {
            return function (r, a) {
                if (!hash[a.shiftId]) {
                    hash[a.shiftId] = { shiftId: a.shiftId, shift: a.shift, item: [], value: 0 };
                    r.push(hash[a.shiftId]);
                }
                hash[a.shiftId].item.push({ itemName: a.item });
                hash[a.shiftId].value += a.value;
                return r;
            };
        }(Object.create(null)), [])
    };

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

A possible approach is to utilize a hash table to reference objects with the same shiftId, allowing for the creation of a new array containing the collected and grouped data.

var data = { rows: [{ shiftId: 1, shift: "Morning", item: "Tea", value: 20 }, { shiftId: 1, shift: "Morning", item: "Coffee", value: 30 }, { shiftId: 2, shift: "Evening", item: "Tea", value: 40 }, { shiftId: 2, shift: "Evening", item: "Coffee", value: 35 }] },
    result = {
        rows: data.rows.reduce(function (hash) {
            return function (r, a) {
                if (!hash[a.shiftId]) {
                    hash[a.shiftId] = { shiftId: a.shiftId, shift: a.shift, item: [], value: 0 };
                    r.push(hash[a.shiftId]);
                }
                hash[a.shiftId].item.push({ itemName: a.item });
                hash[a.shiftId].value += a.value;
                return r;
            };
        }(Object.create(null)), [])
    };

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

Answer №2

To optimize your process, consider implementing a hash table:

var hashTable={};
var inputData={"rows":[
{"shiftId":1,"shift":"Morning","item":"Tea","value":20},
{"shiftId":1,"shift":"Morning","item":"Coffee","value":30},
{"shiftId":2,"shift":"Evening","item":"Tea","value":40},
{"shiftId":2,"shift":"Evening","item":"Coffee","value":35}
]}.rows;

inputData.forEach(function(data){
  var element=(hashTable[data.shiftId]=hashTable[data.shiftId]||{shiftId:data.shiftId,shift:data.shift,items:[],value:0});
   element.items.push({itemName:data.itemName});
   element.value+=data.value;
});

You can then generate the result as follows:

var resultingData={rows:[]};
for(key in hashTable){
 resultingData.rows.push(hashTable[key]);
}

Answer 4

To optimize your process, consider implementing a hash table:

var hashTable={};
var inputData={"rows":[
{"shiftId":1,"shift":"Morning","item":"Tea","value":20},
{"shiftId":1,"shift":"Morning","item":"Coffee","value":30},
{"shiftId":2,"shift":"Evening","item":"Tea","value":40},
{"shiftId":2,"shift":"Evening","item":"Coffee","value":35}
]}.rows;

inputData.forEach(function(data){
  var element=(hashTable[data.shiftId]=hashTable[data.shiftId]||{shiftId:data.shiftId,shift:data.shift,items:[],value:0});
   element.items.push({itemName:data.itemName});
   element.value+=data.value;
});

You can then generate the result as follows:

var resultingData={rows:[]};
for(key in hashTable){
 resultingData.rows.push(hashTable[key]);
}

Answer 5

Answer №3

Utilizing the power of Array.prototype.reduce()

const arrayItems = [{
        "shiftId": 1,
        "shift": "Morning",
        "item": "Tea",
        "value": 20
    },
    {
        "shiftId": 1,
        "shift": "Morning",
        "item": "Coffee",
        "value": 30
    },
    {
        "shiftId": 2,
        "shift": "Evening",
        "item": "Tea",
        "value": 40
    },
    {
        "shiftId": 2,
        "shift": "Evening",
        "item": "Coffee",
        "value": 35
    }
];

const newArray = arrayItems.reduce((accumulator, currentItem, index) => {
    if (!accumulator.length) { // Initial iteration
        accumulator.push(currentItem)
        return accumulator;
    }
    if (accumulator[accumulator.length - 1].shiftId === currentItem.shiftId) { // Check if current shiftId matches last shiftId
        if (!(accumulator[accumulator.length - 1].item instanceof Array)) {
            accumulator[accumulator.length - 1].item = [{ // Convert item to an array
                "itemName": accumulator[accumulator.length - 1].item
            }]
        }
        accumulator[accumulator.length - 1].item.push({ // Add current item name to the last item array
            "itemName": currentItem.item
        });
        accumulator[accumulator.length - 1].value = accumulator[accumulator.length - 1].value + currentItem.value // Value addition
    } else { // If new shiftId
        accumulator.push(currentItem);
    }
    return accumulator;
}, []);

console.log(newArray);

Answer 6

Utilizing the power of Array.prototype.reduce()

const arrayItems = [{
        "shiftId": 1,
        "shift": "Morning",
        "item": "Tea",
        "value": 20
    },
    {
        "shiftId": 1,
        "shift": "Morning",
        "item": "Coffee",
        "value": 30
    },
    {
        "shiftId": 2,
        "shift": "Evening",
        "item": "Tea",
        "value": 40
    },
    {
        "shiftId": 2,
        "shift": "Evening",
        "item": "Coffee",
        "value": 35
    }
];

const newArray = arrayItems.reduce((accumulator, currentItem, index) => {
    if (!accumulator.length) { // Initial iteration
        accumulator.push(currentItem)
        return accumulator;
    }
    if (accumulator[accumulator.length - 1].shiftId === currentItem.shiftId) { // Check if current shiftId matches last shiftId
        if (!(accumulator[accumulator.length - 1].item instanceof Array)) {
            accumulator[accumulator.length - 1].item = [{ // Convert item to an array
                "itemName": accumulator[accumulator.length - 1].item
            }]
        }
        accumulator[accumulator.length - 1].item.push({ // Add current item name to the last item array
            "itemName": currentItem.item
        });
        accumulator[accumulator.length - 1].value = accumulator[accumulator.length - 1].value + currentItem.value // Value addition
    } else { // If new shiftId
        accumulator.push(currentItem);
    }
    return accumulator;
}, []);

console.log(newArray);

Answer 7

Answer №4

let data = {"rows":[
    {"shiftId":1,"shift":"Morning","item":"Tea","value":20},
    {"shiftId":1,"shift":"Morning","item":"Coffee","value":30},
    {"shiftId":2,"shift":"Evening","item":"Tea","value":40},
    {"shiftId":2,"shift":"Evening","item":"Coffee","value":35}
]};
let newData = {"rows":[]};

let lastShiftId = -1;
let newKey = -1;
for(key in data.rows){
  let currentShiftId = data.rows[key].shiftId;

  let obj = {"item":data.rows[key].item};
  if(lastShiftId != currentShiftId){
    newKey++;
    data.rows[key].item = [];
    newData.rows.push(data.rows[key]);    
  }

  newData.rows[newKey].item.push(obj);

  lastShiftId = currentShiftId;
}
console.log(newData.rows);

Fiddle: https://jsfiddle.net/t74ygy9L/

Answer 8

let data = {"rows":[
    {"shiftId":1,"shift":"Morning","item":"Tea","value":20},
    {"shiftId":1,"shift":"Morning","item":"Coffee","value":30},
    {"shiftId":2,"shift":"Evening","item":"Tea","value":40},
    {"shiftId":2,"shift":"Evening","item":"Coffee","value":35}
]};
let newData = {"rows":[]};

let lastShiftId = -1;
let newKey = -1;
for(key in data.rows){
  let currentShiftId = data.rows[key].shiftId;

  let obj = {"item":data.rows[key].item};
  if(lastShiftId != currentShiftId){
    newKey++;
    data.rows[key].item = [];
    newData.rows.push(data.rows[key]);    
  }

  newData.rows[newKey].item.push(obj);

  lastShiftId = currentShiftId;
}
console.log(newData.rows);

Fiddle: https://jsfiddle.net/t74ygy9L/

Combining JSON objects to form a new object within a JSON object using JavaScript

Answer №1

Answer №2

Answer №3

Answer №4

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