Get currencies from countries list with lodash/fp

Question

How can I get an array of currencies with each currencySimbol from this array of countries with Lodash? I used to have this getCurrencies function, but I can't get the Symbols with it, so now I made this getCurrenciesWithSymbol but it's making duplicates and stuff like this {key: "", displayName: "", currencySymbol: undefined}

import { flow, map, uniq, keyBy, compact, pick } from "lodash/fp";


const countries = [
  {
    key: "US",
    name: "United States",
    currency: "USD",
    currencySymbol: "$"
  },
  {
    key: "TW",
    name: "Taiwan",
    currency: "TWD",
    currencySymbol: ""
  }
];


function getCurrencies(countries) {
  const currencies = flow(
    map("currency"),
    uniq,
    compact,
    map((each) => ({ key: each, displayName: each }))
  )(countries);

  return {
    asList: currencies,
    byKey: keyBy("key", currencies)
  };
} // [{key: "USD", displayName: "USD"}, {key: "TW", displayName: "TW"}]


function getCurrenciesWithSymbol(countries) {
  const currencies = flow(
    map(pick(["currency", "currencySymbol"])),
    uniq,
    compact,
    map((each) => ({
      key: each.currency,
      displayName: each.currency,
      currencySymbol: each.currencySymbol
    }))
  )(countries);

  return {
    asList: currencies,
    byKey: keyBy("key", currencies)
  };
}

//Expected
// [
//   { displayName: "USD", key: "USD", currencySymbol: "$" },
//   { displayName: "TW", key: "TW", currencySymbol: "" }
// ];

Answer 1

Use _.uniqBy('currency') to dedupe the array, and then map to the requested form:

const { flow, uniqBy, map } = _;

const getCurrenciesWithSymbol = flow(
  uniqBy('currency'),
  map(({ currency, currencySymbol }) => ({
    displayName: currency,
    key: currency,
    currencySymbol
  }))
);

const countries = [{"key":"US","name":"United States","currency":"USD","currencySymbol":"$"},{"key":"TW","name":"Taiwan","currency":"TWD","currencySymbol":""}];

const result = getCurrenciesWithSymbol(countries);

console.log(result);

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