Merge json object and create new object, inside json object using javascript

Question

My JSON looks like this

{"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}
]}

and I am looking to merge all the same shift and add the values of the merged keys together and create new Object for item to get something looking 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 am try like this

    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;
                        existRow.item = source.item.push(existRow.item);
                    }
                });

But not working correctly. Thanks advance.

What did you attempt so far? What is the code you made so far to try this? — selten98
– selten98, Commented Jun 26, 2017 at 11:06
"Can anyone help me" ... need to help yourself first by showing what you have tried. Stackoverflow is not a free code writing service. The objective here is to help you fix your code — charlietfl
– charlietfl, Commented Jun 26, 2017 at 11:17

Nina Scholz · Accepted Answer · 2017-06-26 11:14:04Z

3

You could use a hash table as a reference to the objects with the same shiftId and return a new array with 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; }

answered Jun 26, 2017 at 11:14

Nina Scholz

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2 Comments

evolutionxbox Over a year ago

Why use (Object.create(null)) and not ({})? Is it to guarantee no inherited properties?

Nina Scholz Over a year ago

@evolutionxbox, because if you have an id like toString, then it is already in the object, because of the prototype. Object.create(null) generates an object without prototypes. it is a really empty opbject.

Jonas Wilms · Accepted Answer · 2017-06-26 11:13:56Z

0

Use a hash table:

var hash={};
var input={"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;

input.forEach(function(row){
  var el=(hash[row.shiftId]=hash[rows.shiftId]||{shiftId:row.shiftId,shift:row.shift,items:[],value:0});
   el.items.push({itemName:row.itemName});
   el.value+=row.value;
});

Now you can create your result like this:

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

answered Jun 26, 2017 at 11:13

Jonas Wilms

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Comments

Mohamed Abbas · Accepted Answer · 2017-06-26 11:22:23Z

Using Array.prototype.reduce()

const arr = [{
        "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 newArr = arr.reduce((acc, item, i) => {
    if (!acc.length) { // First time
        acc.push(item)
        return acc;
    }
    if (acc[acc.length - 1].shiftId === item.shiftId) { // if current shiftId === last shiftId
        if (!(acc[acc.length - 1].item instanceof Array)) {
            acc[acc.length - 1].item = [{ // Convert item to be an array
                "itemName": acc[acc.length - 1].item
            }]
        }
        acc[acc.length - 1].item.push({ // Add current item name to the last item array
            "itemName": item.item
        });
        acc[acc.length - 1].value = acc[acc.length - 1].value + item.value // value addition
    } else { // If new shiftId
        acc.push(item);
    }
    return acc;
}, []);

console.log(newArr);

zuluk · Accepted Answer · 2017-06-26 11:25:33Z

0

a = {"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}
]};
newa = {"rows":[]};

lastshiftid = -1;
newkey = -1;
for(key in a.rows){
  curshiftid = a.rows[key].shiftId;

  o = {"item":a.rows[key].item};
  if(lastshiftid!=curshiftid){
    newkey++;
    a.rows[key].item = [];
    newa.rows.push(a.rows[key]);    
  }

  newa.rows[newkey].item.push(o);

  lastshiftid = curshiftid;
}
console.log(newa.rows);

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

answered Jun 26, 2017 at 11:25

zuluk

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