I'm trying to set a state, which I fetch from an API in the form of an array.
Tried this in every way possible, doesn't work.
Any ideas on how to fix this?
instance is an axios.create that creates the instance to a localhost django server which has CORS-ALLOW-CROSS-ORIGIN True
import React, { useState } from "react";
import { instance } from "../../stores/instance";
const OneList = () => {
const [one, setOne] = useState([]);
const fetchText = async () => {
const response = await instance.get(`/one/list/`);
setOne(response.data);
};
fetchText();
return (
<>
<div>Hello World.</div>
{one.forEach(o => (
<p>o.text</p>
))}
</>
);
};
export default OneList;
Do it like this,
import React, { useState } from "react";
import { instance } from "../../stores/instance";
const OneList = () => {
const [one, setOne] = useState([]);
const fetchText = async () => {
const response = await instance.get(`/one/list/`);
setOne(response.data);
};
useEffect(() => {
fetchText();
},[ any variable you want it to fetch that again ]);
return (
<>
<div>Hello World.</div>
{one.forEach(o => (
<p>o.text</p>
))}
</>
);
};
export default OneList;
This looks to be a good use case for a useEffect hook. Also, you need to await async functions within useEffect statement. The useEffect hook cannot be an async function in itself. Also, the original implementation would result in an infinite loop. The setState function would trigger a re-render which would then trigger the fetch function to fire off again. Consider the following:
import React, { useState, useEffect } from "react";
import { instance } from "../../stores/instance";
const OneList = () => {
const [one, setOne] = useState([]);
const fetchText = async () => {
const request= await instance.get(`/one/list/`);
request.then( r => setOne(r.data))
};
useEffect(() => {
(async () => {
await fetchText();
})();
}, []);
return (
<>
<div>Hello World.</div>
{one.forEach(o => (
<p>o.text</p>
))}
</>
);
};
export default OneList;
Based on you guys' advice, I came up with the below code which works fine so far.
import React, { useState, useEffect } from "react";
import { instance } from "../../stores/instance";
const OneList = () => {
const [one, setOne] = useState([]);
const [el, setEl] = useState(null);
const fetchText = async () => {
let res = await instance.get("/one/list/");
setOne(res.data);
};
useEffect(() => {
(async () => {
await fetchText();
})();
}, []);
useEffect(() => {
const handleClick = e => {
let newEl = document.createElement("input");
newEl.value = e.target.innerHTML;
newEl.id = e.target.id;
newEl.addEventListener("keypress", e => handleInput(e));
newEl.addEventListener("focusout", e => handleInput(e));
e.target.parentNode.replaceChild(newEl, e.target);
newEl.focus();
};
const handleInput = async e => {
console.log(e.type);
if (
e.target.value !== "" &&
(e.key === "Enter" || e.type === "focusout")
) {
let payload = { text: e.target.value };
try {
e.preventDefault();
let res = await instance.put(`/one/update/${e.target.id}`, payload);
let text = res.data.text;
e.target.value = text;
let newEl = document.createElement("span");
newEl.innerHTML = text;
newEl.addEventListener("click", e => handleClick(e));
newEl.id = e.target.id;
e.target.parentNode.replaceChild(newEl, e.target);
} catch (e) {
console.error(e);
}
}
};
setEl(
one.map(o => (
<p>
<span id={o.id} onClick={e => handleClick(e)}>
{o.text}
</span>
</p>
))
);
}, [one]);
return <>{el}</>;
};
export default OneList;
Related
Learning react, currently trying to create a video call web app, however I get this error:
TypeError: Cannot read properties of undefined (reading 'addEventListener')
on this line of code:
useEffect(() => {
peer.addEventListener("negationneeded",handleNegotiation);
return () =>{
peer.removeEventListener("negotionneeded",handleNegotiation);
};
},[]);
handleNegotiation:
const handleNegotiation = useCallback(() => {
const localOffer = peer.localDescription;
socket.emit("call-user",{userID: remoteUserID, offe: localOffer });
}, []);
here is also the whole file:
import React, {useEffect, useCallback, useState} from 'react';
import ReactPlayer from "react-player";
import { useSocket} from "../providers/Socket";
import { usePeer } from "../providers/Peer";
const SessionPage = () => {
const { socket } = useSocket();
const { peer, createOffer, createAnswer,setRemoteAns,sendStream,remoteStream } = usePeer();
const [myStream,setMyStream] = useState(null);
const [remoteUserID, setRemoteUserID] = useState();
const handleNewUserJoined = useCallback(
async(data) =>{
const {userID} = data
console.log("New user joined the session",userID);
const offer = await createOffer();
socket.emit('call-user',{ userID, offer });
setRemoteUserID(userID);
},
[createOffer,socket]
);
const handleIncomingCall = useCallback( async(data) => {
const {from, offer} = data;
console.log("Incoming Call from", from, offer);
const ans = await createAnswer(offer);
socket.emit("call-accepted",{userID: from, ans});
setRemoteUserID(from);
},
[createAnswer, socket] );
const handleCallAccepted = useCallback(async(data) => {
const {ans} = data;
console.log("Call Got Accepted",ans);
await setRemoteAns(ans);
}, [setRemoteAns]);
const getUserMediaStream = useCallback(async() => {
const stream = await navigator.mediaDevices.getUserMedia({audio: true, video: true});
setMyStream(stream);
}, []);
const handleNegotiation = useCallback(() => {
const localOffer = peer.localDescription;
socket.emit("call-user",{userID: remoteUserID, offe: localOffer });
}, []);
useEffect(() => {
socket.on("user-joined",handleNewUserJoined);
socket.on("incoming-call",handleIncomingCall);
socket.on("call-accepted",handleCallAccepted);
//return () =>{
// socket.off("user-joined",handleNewUserJoined);
//socket.off("incoming-call", handleIncomingCall);
//socket.off("call-accepted",handleCallAccepted);
//};
}, [handleCallAccepted,handleIncomingCall, handleNewUserJoined, socket]);
useEffect(() => {
peer.addEventListener("negationneeded",handleNegotiation);
return () =>{
peer.removeEventListener("negotionneeded",handleNegotiation);
};
},[]);
useEffect(() => {
getUserMediaStream();
},[]);
return(
<div className='session-page-container'>
<h1>Hi mom, Im on TV :D</h1>
<h4>You are now online with {remoteUserID}</h4>
<button onClick={(e) => sendStream(myStream)}>Share my video</button>
<ReactPlayer url={myStream} playing muted/>
<ReactPlayer url={remoteStream} playing/>
</div>
)
}
export default SessionPage;
--> Peer file
import React, { useMemo, useEffect, useState, useCallback } from "react";
const peerContext = React.createContext(null);
export const usePeer = () => React.createContext(null);
export const PeerProvider = (props) => {
const [remoteStream, setRemoteStream] = useState(null);
const peer = useMemo(() =>
new RTCPeerConnection({
iceServers: [
{
urls: [
"stun:stun.l.google.com:19302",
"stun:global.stun.twilio.com:3478",
],
},
],
}),
[]
);
const createOffer = async() => {
const offer = await peer.createOffer();
await peer.setLocalDescription(offer);
return offer;
};
const createAnswer = async (offer) => {
await peer.setRemoteDescription(offer);
const answer = await peer.createAnswer();
await peer.setLocalDescription(answer);
return answer;
};
const setRemoteAns = async(ans) =>{
await peer.setRemoteDescription(ans);
};
const sendStream = async(stream) => {
const tracks = stream.getTracks();
for(const track of tracks){
peer.addTrack(track,stream);
}
};
const handleTrackEvent = useCallback((ev) =>{
const streams = ev.streams;
setRemoteStream(streams[0]);
}, [])
useEffect(() => {
peer.addEventListener("track",handleTrackEvent);
return () =>{
peer.removeEventListener("track",handleTrackEvent)
}
},[handleTrackEvent, peer])
return(
<peerContext.Provider value={{ peer, createOffer, createAnswer, setRemoteAns, sendStream,remoteStream}}>{props.children}</peerContext.Provider>
);
};
useEffect with calling addEventListener on peer works earlier than some value assigned there.
Just add check of value existed:
useEffect(() => {
if (!peer) return
peer.addEventListener("track",handleTrackEvent);
return () =>{
peer.removeEventListener("track",handleTrackEvent)
}
},[handleTrackEvent, peer])
I'm having two problems in this code. The first is in the second useEffect. For the reason that I don't understand the useEffect stops working every now and then and causes an error "Cannot read property 'toLowerCase'". Removing the toLowerCase does not solve the problem, but the whole array handling seems to be impossible at that time.
The other problem is in the function addName. setNewName does not set newName. That one I've tried in various kinds of forms, such as setNewName(...newName, {name: '', number: ''}), setNewName('') inside .then and else as well as outside else.
...
import React, {useState, useEffect} from 'react'
import Filter from './components/Filter'
import PersonForm from './components/PersonForm'
import Persons from './components/Persons'
import personService from './services/person'
const App = () => {
const [person, setPerson] = useState([])
const [newName, setNewName] = useState({name: '', number: ''})
const [filteredPerson, setFilteredPerson] = useState([''])
const [searchTerm, setSearchTerm] = useState('')
useEffect(() => {
personService
.getAll()
.then(initialPersons => {
setPerson(initialPersons)
})
}, [])
useEffect( () => {
const results = person.filter( p =>
p.name.toLowerCase().includes(searchTerm) )
setFilteredPerson(results)
},[person,filteredPerson] )
const addName = (event) => {
event.preventDefault()
const nameObject = {
name: newName.name,
number: newName.number
}
if (person.some(p => p.name === newName.name)
) {
window.alert(`${newName.name} is already added to phonebook`)
}
else {
personService
.create(nameObject)
.then(returnedPerson => {
setPerson(person.concat(returnedPerson))
setNewName({name: '', number: ''})
})
console.log('newName', newName.name )
}
}
const handleAddPerson = (event) => {
console.log('event.target.name ', event.target.name)
console.log('event.target.value ', event.target.value)
setNewName({...newName,
[event.target.name]: event.target.value
})
}
const handleSearchTerm = (event) => {
setSearchTerm(event.target.value)
}
return (
<div >
<h2>Phonebook</h2>
<Filter searchTerm={searchTerm} onChange={handleSearchTerm} />
<h3>Add a new</h3>
<PersonForm onSubmit={addName} onChange={handleAddPerson} />
<h2>Numbers</h2>
<Persons list={filteredPerson} />
</div>
);
}
export default App;
...
import axios from 'axios'
const baseUrl = 'http://localhost:3001/persons'
const getAll = () => {
const request = axios.get(baseUrl)
return request.then(response => response.data)
}
const create = newObject => {
const request = axios.post(baseUrl, newObject)
return request.then(response => response.data)
}
const update = (id, newObject) => {
const request = axios.put(`${baseUrl}/${id}`, newObject)
return request.then(response => response.data)
}
/*const updater = {
getAll,
create,
update
}*/
export default {
getAll,
create,
update
}
EDIT
Use async await in your personService so you can return response instead of return request.then(...) something like:
const getAll = async () => {
const response = await axios.get(baseUrl);
return response;
}
After that you can do as follows in your useEffect
useEffect(() => {
(async () => {
const response = await personService.getAll();
if (response.status === 200) {
setPerson(response.data);
const filtered = response.data.filter(item =>
item.name.toLowerCase().includes(searchTerm)
);
setFilteredPerson([...filtered]);
}
})();
}, []);
I am trying to pull data from an Axios Get. The backend is working with another page which is a React component.
In a function however, it doesn't work. The length of the array is not three as it is supposed to be and the contents are empty.
I made sure to await for the axios call to finish but I am not sure what is happening.
import React, { useState, useEffect } from "react";
import { Container } from "#material-ui/core";
import ParticlesBg from "particles-bg";
import "../utils/collagestyles.css";
import { ReactPhotoCollage } from "react-photo-collage";
import NavMenu from "./Menu";
import { useRecoilValue } from "recoil";
import { activeDogAtom } from "./atoms";
import axios from "axios";
var setting = {
width: "300px",
height: ["250px", "170px"],
layout: [1, 3],
photos: [],
showNumOfRemainingPhotos: true,
};
const Collages = () => {
var doggies = [];
//const [dogs, setData] = useState({ dogs: [] });
const dog = useRecoilValue(activeDogAtom);
const getPets = async () => {
try {
const response = await axios.get("/getpets");
doggies = response.data;
//setData(response.data);
} catch (err) {
// Handle Error Here
console.error(err);
}
};
useEffect(() => {
const fetchData = async () => {
getPets();
};
fetchData();
}, []);
return (
<>
<NavMenu />
<ParticlesBg type="circle" margin="20px" bg={true} />
<br></br>
<div>
{doggies.length === 0 ? (
<div>Loading...</div>
) : (
doggies.map((e, i) => {
return <div key={i}>{e.name}</div>;
})
)}
</div>
<Container align="center">
<p> The length of dogs is {doggies.length} </p>
<h1>Knight's Kennel</h1>
<h2> The value of dog is {dog}</h2>
<h2>
Breeders of high quality AKC Miniature Schnauzers in Rhode Island
</h2>
<section>
<ReactPhotoCollage {...setting} />
</section>
</Container>
</>
);
};
export default Collages;
Try doing the following:
const [dogs, setData] = useState([]);
[...]
const getPets = async () => {
try {
const response = await axios.get("/getpets");
doggies = response.data;
setData(response.data);
} catch (err) {
// Handle Error Here
console.error(err);
}
};
const fetchData = async () => {
getPets();
};
useEffect(() => {
fetchData();
}, []);
No idea if it will actually work, but give it a try if you haven't.
If you don't use useState hook to change the array, it won't update on render, so you will only see an empty array on debug.
As far as I can tell you do not return anything from the getPets() function.
Make use of the useState Function to save your doggies entries:
let [doggies, setDoggies ] = useState([]);
const getPets = async () => {
try {
const response = await axios.get("/getpets");
return response.data;
} catch (err) {
// Handle Error Here
console.error(err);
}
return []
};
useEffect(() => {
setDoggies(await getPets());
});
I used setState inside the getPets function. Now it works.
const Collages = () => {
const [dogs, setData] = useState([]);
const dog = useRecoilValue(activeDogAtom);
const getPets = async () => {
try {
const response = await axios.get("/getpets");
setData(response.data);
} catch (err) {
// Handle Error Here
console.error(err);
}
};
useEffect(() => {
const fetchData = async () => {
getPets();
};
fetchData();
}, []);
In my application I have a initial state that start with some values.
In a process, I need to change this state for a empty array, (that is a return of my Api).
I am trying do this, but the value of the state don't change.
What can I do?
My code
import React, {useEffect, useState} from "react";
import "./style.scss";
import Services from "../../services/Services";
export default function Acoplamento({history, match}) {
const [veiculos, setVeiculos] = useState([]);
const [loading, setLoading] = useState(false);
const [type, setType] = useState(1);
const getAllVeiculos = async () => {
setLoading(true);
await Services.VeiculoServices.getAll().then(result => {
setVeiculos(result.data); // Here, i have a array with some objects
}).catch(error => {
error(error.message);
}).finally(() => setLoading(false));
return true;
}
const getOneVeiculos = async () => {
setLoading(true);
await Services.VeiculoServices.get().then(result => {
setVeiculos(result.data); // Here, my return is a empty array, but my state don't chage
}).catch(error => {
error(error.message);
}).finally(() => setLoading(false));
return true;
}
useEffect(() => {
if (type === 1) {
getAllVeiculos();
}
if (type === 2) {
getOneVeiculos();
}
}, [type]);
return (
<div>
<button onClick={() => setType(2)}>Click</button>
{veiculos.map(item => (
<div>{item.name}</div>
))}
</div>
);
}
I guess the problem arises because you did not convert the incoming data to json format. It can solve the following code problem.
import React, {useEffect, useState} from "react";
import "./style.scss";
import Services from "../../services/Services";
export default function Acoplamento({history, match}) {
const [veiculos, setVeiculos] = useState([]);
const [loading, setLoading] = useState(false);
const [type, setType] = useState(1);
const getAllVeiculos = async () => {
setLoading(true);
const response = await Services.VeiculoServices.getAll();
const result = await response.json();
if (result.data) setVeiculos(result.data);
setLoading(false);
}
const getOneVeiculos = async () => {
setLoading(true);
const response = await Services.VeiculoServices.get();
const result = await response.json();
if (result.data) setVeiculos(result.data);
setLoading(false);
}
useEffect(() => {
if (type === 1) {
getAllVeiculos();
}else if (type === 2) {
getOneVeiculos();
}
}, [type]);
return (
<div>
<button onClick={() => setType(2)}>Click</button>
{veiculos.map(item => (
<div>{item.name}</div>
))}
</div>
);
}
I'm trying to take out the fetchImages function from the following component and put it inside a new component:
import React, { useState, useEffect } from 'react';
import axios from 'axios';
import UnsplashImage from './UnsplashImage';
const Collage = () => {
const [images, setImages] = useState([]);
const [loaded, setIsLoaded] = useState(false);
const fetchImages = (count = 10) => {
const apiRoot = 'https://api.unsplash.com';
const accessKey =
'<API KEY>';
axios
.get(`${apiRoot}/photos/random?client_id=${accessKey}&count=${count}`)
.then(res => {
console.log(res);
setImages([...images, ...res.data]);
setIsLoaded(true);
});
};
useEffect(() => {
fetchImages();
}, []);
return (
<div className="image-grid">
{loaded
? images.map(image => (
<UnsplashImage
url={image.urls.regular}
key={image.id}
alt={image.description}
/>
))
: ''}
</div>
);
};
export default Collage;
For this, I created a new component called api.js, removed the entire fetchImage function from the above component and put it in to api.js like this:
api.js
const fetchImages = (count = 10) => {
const apiRoot = 'https://api.unsplash.com';
const accessKey =
'<API KEY>';
axios
.get(`${apiRoot}/photos/random?client_id=${accessKey}&count=${count}`)
.then(res => {
console.log(res);
setImages([...images, ...res.data]);
setIsLoaded(true);
});
};
export default fetchImages;
Next I took setIsLoaded(true); from api.js and paste it inside Collage component like this:
useEffect(() => {
fetchImages();
setIsLoaded(true);
}, []);
Now I can import fetchImages in to Collage component.
However, I don't know what should I do with this line inside the fetchImages function? This needs to go to Collage component, but res.data is not defined inside Collage component.
setImages([...images, ...res.data]);
How should I handle it?
There is many way to do that, but in your case.
You should use
const fetchImages = (afterComplete, count = 10) => {
const apiRoot = 'https://api.unsplash.com';
const accessKey = '<API KEY>';
axios
.get(`${apiRoot}/photos/random?client_id=${accessKey}&count=${count}`)
.then(res => {
console.log(res);
afterComplete(res.data);
});
};
export default fetchImages;
And in your Collage component:
const afterComplete = (resData) =>{
setImages([...images, ...resData]);
setIsLoaded(true);
}
useEffect(() => {
fetchImages(afterComplete);
}, []);
What you can do is create a custom hook ( sort of like a HOC)... Since I don't have an unsplash API key I'll give you an example with a different API but the idea is the same:
Here is your custom hook:
import { useState, useEffect } from 'react';
export const useFetch = url => {
const [data, setData] = useState(null);
const [loading, setLoading] = useState(true);
const fetchUser = async () => {
const response = await fetch(url);
const data = await response.json();
const [user] = data.results;
setData(user);
setLoading(false);
};
useEffect(() => {
fetchUser();
}, []);
return { data, loading };
};
Here is how you can use it in your component:
import { useFetch } from './api';
const App = () => {
const { data, loading } = useFetch('https://api.randomuser.me/');
return (
<div className="App">
{loading ? (
<div>Loading...</div>
) : (
<>
<div className="name">
{data.name.first} {data.name.last}
</div>
<img className="cropper" src={data.picture.large} alt="avatar" />
</>
)}
</div>
);
};
Here is a live demo: https://codesandbox.io/s/3ymnlq59xm