Extracting objects out of arrays

Question

I want to map from this:

companies: {
  apples: {
   Q7: {
    price: 1,
   },
   Q6: {
    price: 1,
   },
  peaches: {
   Q7: {
    price: 1,
   },
   Q6: {
    price: 1,
   },
 },
};

to this:

{ "companies": {
    "apples": [
        {
            "name": "Q7",
            "price": 1
        },{
            "name": "Q6",
            "price": 1
        }
    ],
    "peaches": [
        {
            "name": "Q7",
            "price": 1
        },{
            "name": "Q6",
            "price": 1
        }
    ]
  }
}

How I am trying to achieve this: I have a selector which gives me the companies object and then I map over it and assemble my object but I don't get it quite right.

This is my function:

const weaponProducts = Object.entries(getCompanies(state)).map(([companyType, companies]) => {
        const prod = Object.entries(companies).map(([key, companies]) => {
           return {
               name: key,
               price: companies.price
           }
        });
        return {
            [companyType]: prod
        };
    });

getCompanies(state) returns the following object:

{
    "companies": {
        "apples": {
            "Q7": {
                "price": 1
            },
            "Q6": {
                "price": 1
            }
        },
        "peaches": {
            "Q7": {
                "price": 1
            },
            "Q6": {
                "price": 1
            }
        }
    }
}

The result of the function is the following. But as explained I want it to look like the second code section of my post.

[
  {
    "apples": [
      {
        "name": "Q7",
        "price": 1
      },
      {
        "name": "Q6",
        "price": 1
      },
    ]
  },
  {
    "peaches": [
      {
        "name": "Q7",
        "price": 1
      },
      {
        "name": "Q6",
        "price": 1
      },
    ]
  }
]

Actually if the result shown here is the result of the function, it works correctly. The second companies which u asked to create will break the code cause there is an object without key and with values. I'm not sure if this make sense for you — halilcakar
– halilcakar, Commented Jun 9, 2020 at 21:37
I edited the post above. The last code section of my post is the actual return value of the function. But I dont want it to be like that. Can you please tell me what to adjust in my function in order to make it look like in the second code section. — Aleks
– Aleks, Commented Jun 9, 2020 at 21:43
Yea sure just first can you post what this Object.entries(getCompanies(state)) gives you back? — halilcakar
– halilcakar, Commented Jun 9, 2020 at 22:00
This is the output of the function Halil: jsonblob.com/64de82a7-aa9e-11ea-a88a-4ff68eaea4eb — Aleks
– Aleks, Commented Jun 9, 2020 at 22:12

Ethan Lipkind · Accepted Answer · 2020-06-09 22:25:09Z

since your desired output is an object, not an array, you should use reduce instead of map:

let companies = {
  apples: {
   Q7: {
    price: 1,
   },
   Q6: {
    price: 1,
   },
  },
  peaches: {
   Q7: {
    price: 1,
   },
   Q6: {
    price: 1,
   },
 },
}

let fruit = Object.keys(companies)
let output = fruit.reduce((output, currentFruit) => {
  output[currentFruit] = Object.keys(companies[currentFruit]).map(q => {
    return { name: q, price: companies[currentFruit][q].price }
  })
  return output
}, {});

console.log(output);

(I think there was a syntax error in your companies object, I corrected in the snippet)

Siva Kondapi Venkata · Accepted Answer · 2020-06-10 12:23:10Z

1

You can also take entries and then map the objects accordingly.

var companies = { apples: { Q7: { price: 1, }, Q6: { price: 1, }, }, peaches: { Q7: { price: 1, }, Q6: { price: 1, } }};

const result = (inputObj) =>
  Object.fromEntries(
    Object.entries(inputObj).map(([key, obj]) => [
      key,
      Object.entries(obj).map(([name, val]) => ({ name, ...val })),
    ])
  );

console.log(result(companies));

edited Jun 10, 2020 at 12:23

Siva Kondapi Venkata

11.1k2 gold badges20 silver badges32 bronze badges

answered Jun 10, 2020 at 7:18

Rajneesh

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1 Comment

Aleks Over a year ago

This is even a more elegant solution. Thanks!

richytong · Accepted Answer · 2020-06-09 22:47:56Z

If you're down to try something new, here's a different way to express the desired transformation using a library I authored.

const x = { companies: { apples: { Q7: { price: 1, }, Q6: { price: 1, }, }, peaches: { Q7: { price: 1, }, Q6: { price: 1, }, }, } }

const { pipe, fork, map, tap, get } = rubico

const y = map(map(pipe([
  Object.entries,
  map(fork({
    name: get(0),
    price: get([1, 'price']),
  })),
])))(x)

console.log(JSON.stringify(y, null, 2))

<script src="https://unpkg.com/rubico/index.js"></script>

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