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How to fetch data from more than one API in one project. Covid Map project - day 3.

makneta profile image Magda Rosłaniec Originally published at makneta.herokuapp.com ・4 min read

Last time I was writing about fetching the data from one API using a custom useFetch hook.
Part 2 Covid Map React project day 2
It was a few days ago. In the meanwhile, I decided to add a few more APIs and was trying to find out the best way of doing it. I felt a bit helpless because my app was crashing over and over again. In fact, it was not a problem with fetching the data but with displaying it. But this problem postponed my writing here.

Things I've done:

  1. After all these trials and errors I decided to still be using useFetch hook but fetch data using Promise.all().
  2. First, in App.js I created a list of URLs
  const urls = [
    'https://disease.sh/v3/covid-19/countries',
    'https://disease.sh/v3/covid-19/all',
    'https://disease.sh/v3/covid-19/historical?lastdays=30',
    'https://disease.sh/v3/covid-19/vaccine/coverage/countries?lastdays=30'
  ]
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and pass the urls into the useFetch() function in useFetch.js file

const useFetch = (urls) => 
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  • Then I created a bunch of variables and functions using useState.
 const [countries, setCountries] = useState(null);
    const [countrJson, setCountrJson] = useState(null);
    const [global, setGlobal] = useState(null);
    const [dataHistorical, setDataHistorical] = useState(null)
    const [dataVaccine, setDataVaccine] = useState(null)
    const [loading, setLoading] = useState(false);
    const [error, setError] = useState(null);
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  • Next, I change a bit the try part of my useEffect().
const res = await Promise.all(links.map((url) => fetch(url)))
const data = await Promise.all(res.map((r) => r.json()))
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Promise.all() is the JavaScript method that goes over iterable (list of links in my case) and returns a single Promise for each link or if something goes wrong we have a message about an error.

  • My next step was to transform data from countries API into geoJson to display data on a map. I also need the same data as a simple json, so I created one more variable for it.
  • I set all the data as React states
  setCountries(geoJson)
  setCountrJson(data[0])
  setGlobal(data[1])
  setDataHistorical(data[2])
  setDataVaccine(data[3])
  setLoading(false)
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  • I returned all the data
 return { countries, countrJson, global, dataHistorical, dataVaccine, loading, error}
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  • To make it work I also had to access those variables in App.js component.
const { countries, countrJson, global, dataHistorical, dataVaccine, loading, error } = useFetch(urls)
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useFetch.js

import { useState, useEffect } from 'react';

const useFetch = (urls) => {
    const [countries, setCountries] = useState(null);
    const [countrJson, setCountrJson] = useState(null);
    const [global, setGlobal] = useState(null);
    const [dataHistorical, setDataHistorical] = useState(null)
    const [dataVaccine, setDataVaccine] = useState(null)
    const [loading, setLoading] = useState(false);
    const [error, setError] = useState(null);


    useEffect(() => {
        const fetchData = async () => {
            const links = urls
            console.log(links)
            setLoading(true);
            try {
              const res = await Promise.all(links.map((url) => fetch(url)))
              const data = await Promise.all(res.map((r) => r.json()))


              const geoJson = {
                type: "FeatureCollection",
                features: data[0].map((country = {}) => {
                  const { countryInfo = {}} = country;
                  const { lat, long: lng} = countryInfo;
                    return {
                       type: "Feature",
                       properties: {
                           ...country,
                       },
                       geometry: {
                           type: "Point",
                           coordinates: [lat, lng]
                       }
                    }
                  })
                }

                setCountries(geoJson)
                setCountrJson(data[0])
                setGlobal(data[1])
                setDataHistorical(data[2])
                setDataVaccine(data[3])
                setLoading(false)
            } catch (error) {
                console.log(`Failed to fetch data: ${error.message}`, error)
                setError(error)
            }


        }
        fetchData()
    },[])


    return { countries, countrJson, global, dataHistorical, dataVaccine, loading, error}
}

export default useFetch
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And App.js

import './App.css';
import Map from './components/Map'
import Header from './components/Header'
import TableSection from './components/TableSection'
import { StyledMain } from './components/modules/Sections'

import useFetch from './useFetch'


function App() {

  const urls = [
    'https://disease.sh/v3/covid-19/countries',
    'https://disease.sh/v3/covid-19/all',
    'https://disease.sh/v3/covid-19/historical?lastdays=30',
    'https://disease.sh/v3/covid-19/vaccine/coverage/countries?lastdays=30'
  ]

const { countries, countrJson, global, dataHistorical, dataVaccine, loading, error } = useFetch(urls)

if (error) return <p>Error!</p>;

  return (
    <div className="App">
    <Header />
    {loading ? <p>Loading ...</p> :  <Map countries={countries} /> }
    <StyledMain>
    {loading ? "" : <TableSection countries={countrJson} /> }
    </StyledMain>
    </div>
  );
}

export default App;
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As you can see, I don't use all the data from each API yet, but I wanted to have it solved somehow before going further.

  1. I also refactored part of the code in Map.js to make the variables more readable.
 {props.countries ? props.countries.features.map(place => {
        const { coordinates } = place.geometry    
        const { flag, _id } = place.properties.countryInfo    
        const { country, cases, deaths, recovered, todayCases, todayDeaths, todayRecovered, updated } = place.properties;

        let date = new Date(updated)

        return (
        <Marker icon={redIcon} position={coordinates} key={place.properties.country}>
        <Popup  >
          <img src={flag} style={{width: "30px", height:"auto"}} />
          <h2>{country}</h2>
          <p><strong>Cases:</strong> {cases} | <strong>Cases Today:</strong> {todayCases}</p> 
          <p><strong>Deaths:</strong> {deaths} | <strong>Death Today:</strong> {todayDeaths}</p>
          <p><strong>Recovered:</strong> {recovered} | <strong>Recovered Today:</strong> {todayRecovered}</p>
          <p><strong>Last Update:</strong> {date.toLocaleDateString()}</p>
        </Popup>
        </Marker>
        )
      })
      : ""} 
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I think I will redo this part again but for now, the popup looks like that:
Alt Text

Next step:

  1. Create a table to display data for each country.

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