Dynamically create a new object(s) from JSON data

Question

From a service call, I receive similar JSON data like follows:

myArray: any = [
{item: 'Jelly Beans', areaCode: 321, Company: "Bob's Candy"},
{item: 'Skittles', areaCode: 444, Company: "Jim's Candy"},
{item: 'Snickers', areaCode: 321, Company: "Bob's Candy"},
{item: 'M&Ms', areaCode: 444, Company: "Jim's Candy"},
{item: 'Gummy Bears', areaCode: 123, Company: "Sally's Candy"}];

I need to split this into multiple arrays of objects dynamically, based on areaCode.

Or create a new object dynamically based on areaCode.

this.myArray= this.data.map(item => item.areaCode)
.filter((value, index, self) => self.indexOf(value) === index);

I have thoughts of using the map function and filtering it out based on the areaCode, and then perhaps creating a new object with arrays based on areaCode. I just cannot seem to wrap my head around the process. If anyone could offer some advice I would be grateful.

What is the expected output?

Amardeep Bhowmick
– Amardeep Bhowmick

2019-03-06 05:04:05 +00:00
Commented Mar 6, 2019 at 5:04 — Amardeep Bhowmick
– Amardeep Bhowmick, Commented Mar 6, 2019 at 5:04

Eftakhar · Accepted Answer · 2019-03-06 05:13:31Z

1

you are expecting something like this as output

{
"123":[{"item":"Gummy Bears","areaCode":123,"Company":"Sally's Candy"}],
  "321":[{"item":"Jelly Beans","areaCode":321,"Company":"Bob's Candy"}, 
         {"item":"Snickers","areaCode":321,"Company":"Bob's Candy"}],
  "444":[{"item":"Skittles","areaCode":444,"Company":"Jim's Candy"}, 
         {"item":"M&Ms","areaCode":444,"Company":"Jim's Candy"}]
}

then you can reduce to achieve it

const output = myArray.reduce((res,v) => {
    if(!res[v.areaCode]) {
        res[v.areaCode] = [v] 
    } else {
    res[v.areaCode].push(v)
    }
return res
},{} )

answered Mar 6, 2019 at 5:13

Eftakhar

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Comments

Nick Parsons · Accepted Answer · 2019-03-06 05:17:20Z

You can instead use .reduce to convert your array to an object, and then use Object.values() to get your array of unique objects from the reduces object like so:

const arr = [
{item: 'Jelly Beans', areaCode: 321, Company: "Bob's Candy"},
{item: 'Skittles', areaCode: 444, Company: "Jim's Candy"},
{item: 'Snickers', areaCode: 321, Company: "Bob's Candy"},
{item: 'M&Ms', areaCode: 444, Company: "Jim's Candy"},
{item: 'Gummy Bears', areaCode: 123, Company: "Sally's Candy"}];

const res = Object.values(arr.reduce((acc, {item, areaCode, Company}) => {
  if(areaCode in acc) {
    acc[areaCode].item.push(item);
  } else {
    acc[areaCode] = {item: [item], areaCode, Company};
  };
  
  return acc;
}, {}));

console.log(res);

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