Javascript Array of object join duplicates

Question

I need find dublicates by country code and join them into one object

Array structure is:

[{...},{...}]

Objects

{Country_Code: "RU", Country: "Russia", Provider: "Shell1", Price: "0.123"},
{Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856"},
{Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563"},
{Country_Code: "RU", Country: "Russia", Provider: "Shell2", Price: "0.90890"},
{Country_Code: "RU", Country: "Russia", Provider: "Shell3", Price: "0.90"}

I need get Array of object

[{Country_Code: "RU", Country: "Russia", Provider: "Shell1 - 0.123</br>Shell2 - 0.90890</br>Shell3 - 0.90", Price: "0.123"},
{Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856"},
{Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563"}]

If think must be somethink like

var NewArr =[],NewObj ={};
data.forEach(function(dataItem,index) {
    CC = dataItem.Country_Code;
    counts[CC]= (counts[CC]||0) + 1; // Count duplicates
        if(counts[CC]>1){
            NewObj.Country_Code = dataItem.Country_Code;
            NewObj.Country = dataItem.Country;
            NewObj.Provider = dataItem.Provider + " - " + dataItem.Price + "</br>";
            NewObj.Price = dataItem.Price;
            NewArr[indexOfDup] = NewObj; //but how to know index?
        }else{
            NewArr.push(data[index]);
        }

});

But it wrong, so how to write right syntax?

Answer 1

Here is one solution using reduce. First, I created a map structure using arrays for properties that have multiple values. Then I use the organized structure to format the data to look the way you want:

var data = [{
  Country_Code: "RU",
  Country: "Russia",
  Provider: "Shell1",
  Price: "0.123"
}, {
  Country_Code: "EN",
  Country: "Russia",
  Provider: "Shell",
  Price: "0.76856"
}, {
  Country_Code: "RO",
  Country: "Russia",
  Provider: "Shell",
  Price: "0.563"
}, {
  Country_Code: "RU",
  Country: "Russia",
  Provider: "Shell2",
  Price: "0.90890"
}, {
  Country_Code: "RU",
  Country: "Russia",
  Provider: "Shell3",
  Price: "0.90"
}];

//First, make a map structure for organization
var map = data.reduce((map, el) => {
  let provider = [];
  let price = [];
  if (map[el.Country_Code]) {
    provider = map[el.Country_Code].Provider;
    price = map[el.Country_Code].Price;
  }
  provider.push(el.Provider);
  price.push(el.Price);

  map[el.Country_Code] = {
    Country_Code: el.Country_Code,
    Country: el.Country,
    Provider: provider,
    Price: price
  }
  return map;
}, {});

//Use the data map to display the data however you want
var formatted = Object.values(map).map((el) => {
  return {
    Country_Code: el.Country_Code,
    Country: el.Country,
    Provider: el.Provider.reduce((str, providerEl, idx) => {
      return str += `${providerEl} - ${el.Price[idx]}</br>`;
    }, ''),
    Price: el.Price[0] //this doesnt make sense IMO, but will leave it since that's how you asked for the data
  }
});

console.log(Object.values(formatted));
//{Country_Code: "RU", Country: "Russia", Provider: "Shell1 - 0.123</br>Shell2 - 0.90890</br>Shell3 - 0.90", Price: "0.123"}

Answer 2

There are many ways to solve it. Here is my small contribution, the algorithm that I have proposed doesn't use any search algorithm. So, it can perform relative fast for big arrays.

var myArray = [{Country_Code: "RU", Country: "Russia", Provider: "Shell1", Price: "0.123"},
{Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856"},
{Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563"},
{Country_Code: "RU", Country: "Russia", Provider: "Shell2", Price: "0.90890"},
{Country_Code: "RU", Country: "Russia", Provider: "Shell3", Price: "0.90"}];


var groupByCountryCode = function(xs, key) {
  return xs.reduce(function(rv, x) {
    if(rv[x[key]]){
      // It has found more than one instance

      rv[x[key]][0].Provider += " " + x.Provider;
    }else{
      rv[x[key]] = [];
      rv[x[key]].push(x);
    }
    return rv;
  }, {});
};

var grouppedElementsByKey = groupByCountryCode(myArray,"Country_Code");

var grouppedArray =   Object.keys(grouppedElementsByKey).map(function(key){
  return grouppedElementsByKey[key][0];
});


console.log(grouppedArray);

The final output will be like you have requested.

Answer 3

'use strict';

const data = [
  {Country_Code: "RU", Country: "Russia", Provider: "Shell1", Price: "0.123"},
  {Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856"},
  {Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563"},
  {Country_Code: "RU", Country: "Russia", Provider: "Shell2", Price: "0.90890"},
  {Country_Code: "RU", Country: "Russia", Provider: "Shell3", Price: "0.90"}
];

// create a hashmap by country code
const dataPerCountry = data.reduce((dataCountry, currentValue) => {
  const item = {  }
  if (dataCountry[currentValue.Country_Code]) {
    dataCountry[currentValue.Country_Code].Provider.push(currentValue.Provider);
  } else {
    dataCountry[currentValue.Country_Code] = { 
      ...currentValue,
      Provider: [currentValue.Provider],
    };
  }

  return dataCountry;
}, {});

/** 
 * Transform the hasmap into an array of objects used by the view,
 * also applying the transformation to concat the Providers
 **/
const reducedCountriesVO = Object.keys(dataPerCountry).map((countryCode) => {
  const dataCountry = { ...dataPerCountry[countryCode] };

  dataCountry.Provider = dataCountry.Provider.join('<br>-');

  return dataCountry;
});

console.log(reducedCountriesVO);

Answer 4

You will need array.reduce. Return a array using array.reduce. In this array check if there already exist an object where the country_code exist using findIndex. If it exist then update the property value

let x = [{
    Country_Code: "RU",
    Country: "Russia",
    Provider: "Shell1",
    Price: "0.123"
  },
  {
    Country_Code: "EN",
    Country: "Russia",
    Provider: "Shell",
    Price: "0.76856"
  },
  {
    Country_Code: "RO",
    Country: "Russia",
    Provider: "Shell",
    Price: "0.563"
  },
  {
    Country_Code: "RU",
    Country: "Russia",
    Provider: "Shell2",
    Price: "0.90890"
  },
  {
    Country_Code: "RU",
    Country: "Russia",
    Provider: "Shell3",
    Price: "0.90"
  }
]


let m = x.reduce(function(acc, curr) {
  let findIndex = acc.findIndex((item) => {
    return item['Country_Code'] === curr['Country_Code']
  });
  if (findIndex === -1) {
    acc.push(curr)
  } else {
    acc[findIndex].Provider = acc[findIndex].Provider + ' - ' + acc[findIndex].Price + '<br/>' + curr.Provider + ' - ' + curr.Price
  }

  return acc;


}, []);

console.log(m)

Answer 5

You can use use array.indexOf(someValue) property here.