How to group nested array of objects in js

Question

I have a nested array of objects. I'm trying to group product objects that have the same value.

Each objects has a vendor property containing an email. I am trying to group the objects by matching vendor email

This is how my database looks like:

[
        {
            _id: "622d70a49bd88b1599026318",
            products: [
                {
                    _id: "6223186e2278d4e502f5264a",
                    title: "Product number 1",
                    price: 600,
                    cartQuantity: 1,
                    vendor: {email: "[email protected]"}
                },
                {
                    _id: "622d4e9f9bd88b1599026317",
                    title: "asdas",
                    price: 100,
                    cartQuantity: 5,
                    vendor: {
                        email: "[email protected]"
                    }
                },
                 {
                    _id: "622d4e9f9bd88b1599026317",
                    title: "asdas",
                    price: 100,
                    cartQuantity: 5,
                    vendor: {
                        email: "[email protected]"
                    }
                }
            ]
        }]

I am trying to do it with the reduce method but the problem is with using map inside the reduce. It repeats the object many times. I am also unable to get the grouped objects.

const groupedMap = db.reduce(
    (entryMap, e) => e.products.map((product) => entryMap.set(product.vendor.email, [...entryMap.get(product)||[], product])),
    new Map()
);

The above code output is:

My expectation is:

[0: {"[email protected]" => Array(1)}
   key: "[email protected]"
   value: [{_id: '6223186e2278d4e502f5264a', title: 'Product number 1', price: 600, cartQuantity: 1, vendor: {email: "[email protected]"}}],
1: {"[email protected]" => Array(2)}
key: "[email protected]"
   value: [{_id: '6223186e2278d4e502f5264a', title: 'Product number 1', price: 600, cartQuantity: 1, vendor: {email: "[email protected]"}},
{_id: '6223186e2278d4e502f5264a', title: 'Product number 1', price: 600, cartQuantity: 1, vendor: {email:"[email protected]"}}
]
]

Sorry, I'm a bit confused by the the code you provided as the expected result. Also, is the solution you are after needs to cover more "products" lists or just 1? — Avi
– Avi, Commented Mar 13, 2022 at 20:31

Ameer · Accepted Answer · 2022-03-13 18:33:30Z

Loop through each item in the array and see if the vendor email exists as a key already in a dictionary, if it exists push it to that array, otherwise set the value of the vendor email key equal to an array with the current item in it

See code below

const data = [{
  _id: "622d70a49bd88b1599026318",
  products: [{
      _id: "6223186e2278d4e502f5264a",
      title: "Product number 1",
      price: 600,
      cartQuantity: 1,
      vendor: {
        email: "[email protected]"
      }
    },
    {
      _id: "622d4e9f9bd88b1599026317",
      title: "asdas",
      price: 100,
      cartQuantity: 5,
      vendor: {
        email: "[email protected]"
      }
    },
    {
      _id: "622d4e9f9bd88b1599026317",
      title: "asdas",
      price: 100,
      cartQuantity: 5,
      vendor: {
        email: "[email protected]"
      }
    }
  ]
}];

const mapped = {};
data[0].products.forEach(item => {
  if (item.vendor.email in mapped) return mapped[item.vendor.email].push(item);

  mapped[item.vendor.email] = [item];
});

const expectedFormat = Object.keys(mapped).map(key => {
  const o = {};
  o[key] = mapped[key];
  
  return o;
});

console.log(expectedFormat)

Grezisek R · Accepted Answer · 2022-03-13 18:31:41Z

0

try to make an object where key is the value you group by. the next step is foreach in which you check each object in the array, whether the value you are looking for is in the object made - if not, then you filter the array by searched value and add the result to your object

answered Mar 13, 2022 at 18:31

Grezisek R

112 bronze badges

1 Comment

EzioMercer Over a year ago

It would be better if you add some runnable code or example of code

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