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How to pass data from an axios API inside a state using React?

I have an api (an arr of objects) which I need to pass into a state, so that I can then pass that data inside a component to show it on the website.
1st approach:
// pulls the api data
const newData = axios.get(url).then((resp) => {
const apiData = resp.data;
apiData.map((video) => {
return video;
});
});
// sets the state for the video
const [selectedVideo, setSelectedVideo] = useState(newData[0]);
const [videos] = useState(videoDetailsData);
...
return (
<>
<FeaturedVideoDescription selectedVideo={selectedVideo} />
</>
)
2nd approach:
const useAxiosUrl = () => {
const [selectedVideo, setSelectedVideo] = useState(null);
useEffect(() => {
axios
.get(url)
.then((resp) => setSelectedVideo(resp.data))
});
return selectedVideo;
}
...
return (
<>
<FeaturedVideoDescription selectedVideo={selectedVideo} />
</>
)
both of these approaches don't seem to work. What am I missing here?

The correct way is to call your axios method inside the useEffect function.
const fetchData = axios.get(url).then((resp) => setSelectedVideo(resp.data)));
useEffect(() => {
fetchData();
}, [])
or if you need async/await
useEffect(() => {
const fetchData = async () => {
const response = await axios.get(url);
setSelectedVideo(resp.data);
}
fetchData();
}, [])

Proper way to fetch from another component - ReactJS

I have a component that fetches the data properly but I want to encapsulate it in a helper. I've tried many things but I'm stuck.
This is the component that works:
export const Carousel = () => {
const [ lotteries, setLotteries ] = useState({});
const [ isLoading, setisLoading ] = useState(true);
useEffect(() => {
async function fetchAPI() {
const url = 'https://protected-sea-30988.herokuapp.com/https://www.lottoland.com/api/drawings;'
let response = await fetch(url)
response = await response.json()
setLotteries(response)
setisLoading(false)
}
fetchAPI()
}, [])
return (
<>
{
isLoading ? (
<span>loading</span>
) : (
<Slider >
{
Object.keys(lotteries).map((lottery, idx) => {
return (
<Slide
key={ idx }
title={ lottery }
prize={ lotteries[lottery].next.jackpot }
day={ lotteries[lottery].next.date.day }
/>
)
})
}
</Slider>
)}
</>
);}
And this is the last thing I've tried so far. This is the component without the fetch
export const Carousel = () => {
const [ lotteries, setLotteries ] = useState({});
const [ isLoading, setIsLoading ] = useState(true);
useEffect(() => {
getLotteries()
setLotteries(response)
setIsLoading(false)
}, [])
And this is where I tried to encapsulate the fetching.
export const getLotteries = async() => {
const url = 'https://protected-sea-30988.herokuapp.com/https://www.lottoland.com/api/drawings;'
let response = await fetch(url)
response = await response.json()
return response;
}
I'm a bit new to React, so any help would be much appreciated. Many thanks.

To get the fetched data from getLotteries helper you have to return a promise
export const getLotteries = async() => {
const url = 'https://protected-sea-
30988.herokuapp.com/https://www.lottoland.com/api/drawings;'
let response = await fetch(url)
return response.json()
}
and call it as async/await
useEffect(async() => {
let response= await getLotteries()
setLotteries(response)
setIsLoading(false)
}, [])

If you want to separate the logic for requesting a URL into another helper function, you can create a custom hook.
// customHook.js
import { useEffect, useState } from 'react';
export function useLotteries() {
const [lotteries, setLotteries] = useState(null);
useEffect(() => {
fetch('https://protected-sea-30988.herokuapp.com/https://www.lottoland.com/api/drawings;')
.then(response => response.json())
.then(json => setLotteries(json));
}, []);
return lotteries;
}
// Carousel.js
import { useLotteries } from "./customHook.js";
export const Carousel = () => {
const lotteries = useLotteries();
if (lotteries) {
return; /* Your JSX here! (`lotteries` is now contains all the request responses) */
} else {
return <Loader />; // Or just null if you don't want to show a loading indicator when your data hasn't been received yet.
}
};

State update not finised before other update starts

I have this object:
{
"Widget1": "notes",
"Widget2": "clock",
"Widget3": "weather",
}
It is transferred to my react app via a rest API.
const Widgets: React.FC = () => {
interface DataType {
[key: string]: string;
}
const [data, setData] = React.useState<DataType>();
const [isLoaded, setIsLoaded] = React.useState<boolean>(false);
React.useEffect(() => {
const fetchData = async () => {
fetch("http://localhost:1202/data")
.then((res) => res.json())
.then((json) => {
setData(json);
console.log("json", json);
});
};
fetchData();
setIsLoaded(true);
}, []);
const [currentWidget1, setCurrentWidget1] = React.useState<string>("wetter");
const widget1Handler = (widget: string) => {};
if (!isLoaded) {
return (
<div>loading...<div>
);
} else {
return (
<component data={data}></component>
);
}
};
export default Widgets;
The problem is that apparently it takes longer for setData to be updated than for setIsLoaded to update.
So component is loaded before the data is stored in the data object.
Is there a quick fix for that?

You can check if there is data then set state: data && setData(json)

Yeah, you can use something like
if (Object.keys(data) > 0) {
<Component data={data}></Component>
}
else {
<div>loading...<div>
}
No Need to use isLoaded
FYI: React Components are always called with first character in uppercase Component

Fetch data with a custom React hook

I'm newbie in React but I'm developing an app which loads some data from the server when user open the app. App.js render this AllEvents.js component:
const AllEvents = function ({ id, go, fetchedUser }) {
const [popout, setPopout] = useState(<ScreenSpinner className="preloader" size="large" />)
const [events, setEvents] = useState([])
const [searchQuery, setSearchQuery] = useState('')
const [pageNumber, setPageNumber] = useState(1)
useEvents(setEvents, setPopout) // get events on the main page
useSearchedEvents(setEvents, setPopout, searchQuery, pageNumber)
// for ajax pagination
const handleSearch = (searchQuery) => {
setSearchQuery(searchQuery)
setPageNumber(1)
}
return(
<Panel id={id}>
<PanelHeader>Events around you</PanelHeader>
<FixedLayout vertical="top">
<Search onChange={handleSearch} />
</FixedLayout>
{popout}
{
<List id="event-list">
{
events.length > 0
?
events.map((event, i) => <EventListItem key={event.id} id={event.id} title={event.title} />)
:
<InfoMessages type="no-events" />
}
</List>
}
</Panel>
)
}
export default AllEvents
useEvents() is a custom hook in EventServerHooks.js file. EventServerHooks is designed for incapsulating different ajax requests. (Like a helper file to make AllEvents.js cleaner) Here it is:
function useEvents(setEvents, setPopout) {
useEffect(() => {
axios.get("https://server.ru/events")
.then(
(response) => {
console.log(response)
console.log(new Date())
setEvents(response.data.data)
setPopout(null)
},
(error) => {
console.log('Error while getting events: ' + error)
}
)
}, [])
return null
}
function useSearchedEvents(setEvents, setPopout, searchQuery, pageNumber) {
useEffect(() => {
setPopout(<ScreenSpinner className="preloader" size="large" />)
let cancel
axios({
method: 'GET',
url: "https://server.ru/events",
params: {q: searchQuery, page: pageNumber},
cancelToken: new axios.CancelToken(c => cancel = c)
}).then(
(response) => {
setEvents(response.data)
setPopout(null)
},
(error) => {
console.log('Error while getting events: ' + error)
}
).catch(
e => {
if (axios.isCancel(e)) return
}
)
return () => cancel()
}, [searchQuery, pageNumber])
return null
}
export { useEvents, useSearchedEvents }
And here is the small component InfoMessages from the first code listing, which display message "No results" if events array is empty:
const InfoMessages = props => {
switch (props.type) {
case 'no-events':
{console.log(new Date())}
return <Div className="no-events">No results :(</Div>
default:
return ''
}
}
export default InfoMessages
So my problem is that events periodically loads and periodically don't after app opened. As you can see in the code I put console log in useEvents() and in InfoMessages so when it's displayed it looks like this:
logs if events are displayed, and the app itself
And if it's not displayed it looks like this: logs if events are not displayed, and the app itself
I must note that data from the server is loaded perfectly in both cases, so I have totally no idea why it behaves differently with the same code. What am I missing?

Do not pass a hook to a custom hook: custom hooks are supposed to be decoupled from a specific component and possibly reused. In addition, your custom hooks return always null and that's wrong. But your code is pretty easy to fix.
In your main component you can fetch data with a custom hook and also get the loading state like this, for example:
function Events () {
const [events, loadingEvents] = useEvents([])
return loadingEvents ? <EventsSpinner /> : <div>{events.map(e => <Event key={e.id} title={e.title} />}</div>
}
In your custom hook you should return the internal state. For example:
function useEvents(initialState) {
const [events, setEvents] = useState(initialState)
const [loading, setLoading] = useState(true)
useEffect(function() {
axios.get("https://server.ru/events")
.then(
(res) => {
setEvents(res.data)
setLoading(false)
}
)
}, [])
return [events, loading]
}
In this example, the custom hook returns an array because we need two values, but you could also return an object with two key/value pairs. Or a simple variable (for example only the events array, if you didn't want the loading state), then use it like this:
const events = useEvents([])

This is another example that you can use, creating a custom hook that performs the task of fetching the information
export const useFetch = (_url) => {
const [data, setData] = useState(null);
const [loading, setLoading] = useState(true);
const [error, setError] = useState(true);
useEffect(function() {
setLoading('procesando...');
setData(null);
setError(null);
const source = axios.CancelToken.source();
setTimeout( () => {
axios.get( _url,{cancelToken: source.token})
.then(
(res) => {
setLoading(false);
console.log(res.data);
//setData(res);
res.data && setData(res.data);
// res.content && setData(res.content);
})
.catch(err =>{
setLoading(false);
setError('si un error ocurre...');
})
},1000)
return ()=>{
source.cancel();
}
}, [_url])

React programmatically recall a hook

https://codesandbox.io/s/react-hooks-usefetch-cniul
Please see above url for a very simplified version of my code.
I want to be able to refetch data from an API with my hook, within an interval (basically poll an endpoint for data).
What I want is to be able to just call something like refetch (as I've shown in the code as a comment), which would essentially just call fetchData again and update state with the response accordingly.
What's the best way to go about this? The only way I can think of is to add a checker variable in the hook which would be some sort of uuid (Math.random() maybe), return setChecker as what is refetch and just add checker to the array as 2nd useEffect argument to control rerendering. So whenever you call refetch it calls setChecker which updates the random number (checker) and then the function runs again.
Obviously this sounds "hacky", there must be a nicer way of doing it - any ideas?

If you want to have a constant poll going, I think you can move the setInterval() into the hook like so:
function useFetch() {
const [data, setDataState] = useState(null);
const [loading, setLoadingState] = useState(true);
useEffect(() => {
function fetchData() {
setLoadingState(true);
fetch(url)
.then(j => j.json())
.then(data => {
setDataState(data);
setLoadingState(false);
});
}
const interval = setInterval(() => {
fetchData();
}, 5000);
fetchData();
return () => clearInterval(interval);
}, []);
return [
{
data,
loading
}
];
}
Remember to include the return () => clearInterval(interval); so the hook is cleaned up correctly.

import React, { useEffect, useState, useCallback } from "react";
import ReactDOM from "react-dom";
const url = "https://api.etilbudsavis.dk/v2/dealerfront?country_id=DK";
function useFetch() {
const [data, setDataState] = useState(null);
const [loading, setLoadingState] = useState(true);
const refetch = useCallback(() => {
function fetchData() {
console.log("fetch");
setLoadingState(true);
fetch(url)
.then(j => j.json())
.then(data => {
setDataState(data);
setLoadingState(false);
});
}
fetchData();
}, []);
return [
{
data,
loading
},
refetch
// fetchData <- somehow return ability to call fetchData function...
];
}
function App() {
const [
{ data, loading },
refetch
// refetch
] = useFetch();
useEffect(() => {
const id = setInterval(() => {
// Use the refetch here...
refetch();
}, 5000);
return () => {
clearInterval(id);
};
}, [refetch]);
if (loading) return <h1>Loading</h1>;
return (
<>
<button onClick={refetch}>Refetch</button>
<code style={{ display: "block" }}>
<pre>{JSON.stringify(data[0], null, 2)}</pre>
</code>
</>
);
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

Maybe the following will work, it needs some adjustments to useFetch but you can still call it normally in other places.
//maybe you can pass url as well so you can use
// it with other components and urls
function useFetch(refresh) {
//code removed
useEffect(() => {
//code removed
}, [refresh]);
//code removed
}
const [refresh, setRefresh] = useState({});
const [{ data, loading }] = useFetch(refresh);
useEffect(() => {
const interval = setInterval(
() => setRefresh({}), //forces re render
5000
);
return () => clearInterval(interval); //clean up
});

Simple answer to question:
export default function App() {
const [entities, setEntities] = useState();
const [loading, setLoadingState] = useState(true);
const getEntities = () => {
setLoadingState(true);
//Changet the URL with your own
fetch("http://google.com", {
method: "GET",
})
.then((data) => data.json())
.then((resp) => {
setEntities(resp);
setLoadingState(false);
});
};
useEffect(() => {
const interval = setInterval(() => {
getEntities();
}, 5000);
return () => clearInterval(interval);
}, []);
}