Recently am learning React hooks and am now doing a search app which have to call API then return the list movies correspond to what i type in the search box.
My code here:
useFetch.js
import { useState, useEffect } from 'react'
export const useFetch = (url, initialState) => {
const [data, setData] = useState(initialState)
const [loading, setLoading] = useState(true)
useEffect(() => {
async function fetchMovies() {
const response = await fetch(url)
const data = await response.json()
setData(data.Search)
setLoading(false)
}
fetchMovies()
}, [url])
return { data, loading }
}
App.js
import React, { useState } from 'react'
import Search from './components/Search'
import Result from './components/Result'
import Loading from './components/Loading'
import { useFetch } from './utils/useFetch'
export default function App() {
const [key, setKey] = useState('Iron man')
const onSearch = (key) => {
setKey(key)
}
const {data, loading} = useFetch(`https://www.omdbapi.com/?s=${key}&apikey=${API_KEY}`)
return (
<>
<Search handleSearch={onSearch}/>
<Loading isLoading={loading} />
<Result movies={data}/>
</>
)
}
As far as i understand after clicking button search function call API will be fired and return the result as expect. I can't put
const {data, loading} = useFetch(`https://www.omdbapi.com/?s=${key}&apikey=${API_KEY}`)
inside onSearch function. Follow the code function call API is automatically called whenever the app start and return undefined as result.
Can anyone help me out and explain why?
You are correct in your understanding of how hooks can only be called at the top level in a react component. Make the following changes and the API won't get called the first time around but will get called subsequently.
Use url state variable and extract generateUrl logic outside the component:
function generateUrl(key) {
return `https://www.omdbapi.com/?s=${key}&apikey=${API_KEY}`
}
function MyComponent() {
const [url, setUrl] = React.useState('');
//...
}
Check for url presence in useFetch hook by wrapping fetchMovies() call in an if condition. This way, API won't trigger since default value of url is empty.
import { useState, useEffect } from 'react'
export const useFetch = (url, initialState) => {
const [data, setData] = useState(initialState)
const [loading, setLoading] = useState(true)
useEffect(() => {
async function fetchMovies() {
const response = await fetch(url)
const data = await response.json()
setData(data.Search)
setLoading(false)
}
if(url) {
fetchMovies()
}
}, [url])
return { data, loading }
}
Finally, modify onSearch
const onSearch = (key) => {
setUrl(generateUrl(key))
}
Perhaps you could expose setUrl through something like:
return { data, loading, onSearch: (key) => setUrl(generateUrl(key)) }
Related
why is fetchReviews not fetching?
Originally didn't use fetchData in use effect.
Ive tried using useDispatch.
BusinessId is being passed into the star component.
no errors in console.
please let me know if theres other files you need to see.
thank you!
star component:
import React, { useState, useEffect } from 'react';
import { useDispatch } from 'react-redux';
import {AiFillStar } from "react-icons/ai";
import { fetchReviews } from '../../actions/review_actions';
function Star(props) {
const [rating, setRating] = useState(null);
// const [reviews, setReview] = useState(props.reviews)
// const dispatch = useDispatch();
useEffect(() => {
const fetchData = async () => {
await fetchReviews(props.businessId)
};
fetchData();
console.log(props);
// getAverageRating();
});
const getAverageRating = () => {
let totalStars = 0;
props.reviews.forEach(review => {totalStars += review.rating});
let averageStars = Math.ceil(totalStars / props.reviews.length);
setRating(averageStars);
}
return (
<div className='star-rating-container'>
{Array(5).fill().map((_, i) => {
const ratingValue = i + 1;
return (
<div className='each-star' key={ratingValue}>
<AiFillStar
className='star'
color={ratingValue <= rating ? '#D32322' : '#E4E5E9'}
size={24} />
</div>
)
})}
</div>
);
};
export default Star;
star_container:
import { connect } from "react-redux";
import { withRouter } from "react-router-dom";
import Star from "./star";
import { fetchReviews } from "../../actions/review_actions";
const mSTP = state => {
return {
reviews: Object.values(state.entities.reviews)
};
}
const mDTP = dispatch => {
return {
fetchReviews: businessId => dispatch(fetchReviews(businessId))
};
};
export default connect(mSTP, mDTP)(Star);
console image
why is fetchReviews not fetching? Originally didn't use fetchData in use effect. Ive tried using useDispatch. BusinessId is being passed into the star component. no errors in console.
edit!***
made some changes and added useDispatch. now it wont stop running. its constantly fetching.
function Star(props) {
const [rating, setRating] = useState(null);
const [reviews, setReview] = useState(null)
const dispatch = useDispatch();
useEffect(() => {
const fetchData = async () => {
const data = await dispatch(fetchReviews(props.businessId))
setReview(data);
};
fetchData();
// console.log(props);
// getAverageRating();
}), [];
ended up just calling using the ajax call in the useEffect.
useEffect(() => {
const fetchReviews = (businessId) =>
$.ajax({
method: "GET",
url: `/api/businesses/${businessId}/reviews`,
});
fetchReviews(props.businessId).then((reviews) => getAverageRating(reviews));
}), [];
if anyone knows how i can clean up and use the dispatch lmk.
ty all.
useEffect(() => {
const fetchData = async () => {
const data = await dispatch(fetchReviews(props.businessId))
setReview(data);
};
fetchData();
// console.log(props);
// getAverageRating();
}), [];
dependency array is outside the useEffect. Since useEffect has no dependency option passed, function inside useEffect will run in every render and in each render you keep dispatching action which changes the store which rerenders the component since it rerenders code inside useEffect runs
// pass the dependency array in correct place
useEffect(() => {
const fetchData = async () => {
const data = await dispatch(fetchReviews(props.businessId))
setReview(data);
};
fetchData();
// console.log(props);
// getAverageRating();
},[]), ;
Passing empty array [] means, code inside useEffect will run only once before your component mounted
In a react app, when creating a component, I use useEffect to handle a HTTP request via a custom hook (which fetch via a useCallback). Then, to parse the parameters for the request, I have a layer for services which return the expected values.
As a result, this workflow keeps re-rendering in a loop and the apps gets stacked.
Component:
import React, { Fragment, useContext, useEffect, useState } from 'react';
import { NavLink } from 'react-router-dom';
import { useParams } from 'react-router-dom';
import { useTranslation } from 'react-i18next';
import { getProject } from '../../../services/Project.service';
import { AuthContext } from '../../../shared/context/auth.context';
import { NavOptions } from '../../../shared/constants/NavOptions';
import { useHttpClient } from '../../../shared/hooks/http.hook';
import SideNavigation from '../../../shared/components/Navigation/SideNavigation/SideNavigation';
import NavLinks from '../../../shared/components/Navigation/NavLinks/NavLinks';
import './Dashboard.css';
const Dashboard = (props) => {
console.log('Dashboard...');
const { isLoading, error, sendRequest, clearError } = useHttpClient();
const [project, setProject] = useState();
const auth = useContext(AuthContext);
const projectId = useParams().projectId;
const getProject = async () => {
console.log('getProject...');
console.log('auth', auth.token);
const response = await sendRequest(getProject(projectId, auth.token));
if (response.status === 201) {
const responseData = await response.json();
console.log('project:', responseData);
setProject(responseData);
} else {
console.log('getting buildings failed!');
const error = await response.json();
}
};
useEffect(() => {
projectId && getProject();
}, []);
const { t, i18n } = useTranslation();
let content = (
<div className="bim-y-dashboard">
.
.
.
</div>
);
return (
<Fragment>
<SideNavigation>
<NavLinks options={NavOptions.PROJECT} projectId />
</SideNavigation>
<MainContent>{content}</MainContent>
</Fragment>
);
};
export default Dashboard;
Custom hook:
export const useHttpClient = () => {
const auth = useContext(AuthContext);
const [isLoading, setIsLoading] = useState(false);
const [error, setError] = useState();
const activeHttpRequests = useRef([]);
const sendRequest = useCallback(
async (url, method = 'GET', body = null, headers = {}) => {
console.log('sendRequest...');
console.log('url', url);
console.log('method', method);
console.log('body', body);
console.log('headers', headers);
},[]);
const clearError = () => {
setError(null);
};
useEffect(() => {
return () => {
activeHttpRequests.current.forEach(abortCtrl => abortCtrl.abort());
};
}, []);
return { isLoading, error, sendRequest, clearError };
};
Service:
export const getProject = (projectId, token) => {
console.log('getProject...');
return (`/projects/id/${projectId}`, 'GET', null, {
'Content-Type': 'application/json',
Authorization: 'Bearer ' + token,
});
}
What am I missing to avoid this constant re-rendering?
Thanks in advance.
I have the feeling your issue is in code you have not shared, as the above looks legit.
Things you can try:
Comment out const auth = useContext(AuthContext); in your custom hook to make sure the culprit is not in your context
Make sure const response = await sendRequest(..) returns what you are expecting
Add a new hook, something like const [data, setData] = useState(null), then after you get a response, set it in your hook setData(response)
Finally, in your useEffect, update your condition as projectId && !data && getProject();
That will ensure your re rendering issue is neither on your auth context nor in your fetch request.
Hope that helps; if not, please update the question with the full code of your component and I'll take a second look :)
RESOLVED:
Found this post: Link
It explains that because of sendRequest method, it keeps re-rendering.
I am relatively new to react hooks and I am trying to create this custom hook to handle CRUD operations for my API.
This is the hook file:
import React, { useState, useEffect } from "react";
const useApi = (url, headers = { method: "GET" }, payload = null) => {
const [isLoading, setIsLoading] = useState(true);
const [apiData, setApiData] = useState(null);
const [serverError, setServerError] = useState(null);
const [api, setApi] = useState({});
const list = async () => {
try {
const resp = await fetch(url);
const data = await resp?.json();
setApiData(data);
setIsLoading(false);
} catch (error) {
setServerError(error);
} finally {
setIsLoading(false);
}
};
const create = async () => {
try {
const resp = await fetch(url, (headers = { method: "POST" }), payload);
const data = await resp?.json();
setApiData(data);
setIsLoading(false);
} catch (error) {
setServerError(error);
} finally {
setIsLoading(false);
}
};
setApi({
...api,
list: list,
create: create
});
return { isLoading, apiData, serverError, api };
};
export default useApi;
However, when I call api.list() in my main component inside a useEffect() hook, I get an infinite loop.
Sample component call:
import { useEffect } from "react";
import useApi from "./useApi";
export default function App() {
const {
isLoading: loading,
apiData: students,
serverError: error,
api
} = useApi("https://59f0f160ce72350012bec011.mockapi.io/students");
console.log(loading, students, error, api);
useEffect(() => {
api.list();
}, [api]);
return (
<div className="App">
<h1>list</h1>
{loading ? "loading" : students.map((x) => x.name)}
</div>
);
}
Here's the sandbox for it:
https://codesandbox.io/s/cocky-chebyshev-d9q89?file=/src/App.js:0-492
Can anyone help me understand the issue?
Thank you in advance!
This is what is causing the infinite loop:
setApi({
...api,
list: list,
create: create
});
You are not supposed to call setState() during a render.
In your case, you don't need to useState for the api object, you can just return it on every render:
return {
isLoading,
apiData,
serverError,
api: { list, create }
};
Here is a link to the fixed sandbox
Also, another warning: this code will repeatedly call api.list().
useEffect(() => {
api.list();
}, [api]);
Since api changes on every render, it will repeatedly call api.list().
This is the object that changes on every render:
return { isLoading, apiData, serverError, api };
You can ensure that you only call api.list() one time by using a ref.
import { useRef } from 'react'
// In the component
const gotRef = useRef(false)
useEffect(() => {
if (!gotRef.current) {
api.list();
gotRef.current = true
}
}, [api]);
My useEffect hook dont seem to be running the block of code within its scope. Not exactly sure why, when i debug it the useEffect hook gets hit but the code within it never runs. I have placed a break point and it never lands on it.
import {useState, useEffect} from "react";
const useApiResult = (request) => {
const [results, setResults] = useState(null);
const [error, setError] = useState(null);
useEffect(() => {
loadData(request);
}, [request]);
const loadData = async (request) => {
console.log(request)
try
{
const response = await fetch(request);
if(response.ok) {
setResults(await response.json());
setError(null);
} else {
setError(await response.text());
}
}
catch (err) {
setError(err);
}
}
return [results, error];
};
export default useApiResult;
Where I call useApiResult
import { useMemo } from 'react';
import { getPokemons } from '../requests';
import useApiResult from '../customHooks/useApiResults';
const usePokemons = () => {
const request = useMemo(() => getPokemons(), []);
return useApiResult(request);
}
export default usePokemons;
getpokemons.js
export const BASE_URL = "https://pokeapi.co/api/v2";
const createUrl = (base, path) => `${base}${path}`;
export const getPokemons = () => [
createUrl(BASE_URL, "/pokemon?offset=300&limit=10"),
{
method: "GET",
}
];
My steps to catch issue:
When I looked in your sandbox I noticed error: results is null
I also found const [results, error] = usePokemons(); in PokemonList component, so I thought that this error is not necessary, I just removed it. Because you never used it in component.
I still got results is null I just add condition render via &&. It looks like:
results &&
results.map((key, i) => (
I got new error: results.map is not a function. It means that results is not array. When I saw at results I noticed that it has inside array with the same name. So I just add resuts after a dot.
results &&
results.results.map((key, i) => (
Here we go:)
I'm attempting to call a Graph QL Query after receiving data from my useEffect hook. I need the data from the response to use in the Query. Hooks however cannot be called conditionally. If I take away the condition however, loadedAnime will be undefined. How do I get around this restraint?
import React, { useEffect, useState } from "react";
import { useParams } from "react-router-dom";
import AnimeBanner from "../components/AnimeBanner";
import { useHttpClient } from "../Hooks/http-hook";
import { GetAnimeData } from "../GraphQLFunctions";
import { useQuery } from "#apollo/react-hooks";
import gql from "graphql-tag";
const GET_ANIME_INFO = gql`
query GetAnimeInfo($name: String!) {
Media(search: $name) {
title {
romaji
english
native
userPreferred
}
episodes
id
bannerImage
}
}
`;
const Anime = (props) => {
//Logic for getting anime data from mongoDB (episodes, name, cover image)
const { isLoading, error, sendRequest } = useHttpClient();
const [loadedAnime, setloadedAnime] = useState();
const URLTitle = useParams().URLTitle;
useEffect(() => {
const fetchAnime = async () => {
try {
const responseData = await sendRequest(
"http://localhost:5000/api/anime/" + URLTitle
);
setloadedAnime(responseData.animeData[0]);
} catch (err) {
console.log(err);
}
};
fetchAnime();
}, [sendRequest, URLTitle]);
if (isLoading || error) {
return null;
}
//Logic for getting anime data from anilist (Descriptions, tags, banner, trailer, etc.)
const { apiData, apiLoading, apiError } = useQuery(GET_ANIME_INFO, {
variables: {
name: loadedAnime.anime_name,
},
});
if (apiLoading || apiError) {
return null;
}
return <AnimeBanner src={apiData.Media.bannerImage} />;
};
export default Anime;
Short Answer: You can checkout useLazyQuery instead of useQuery.
Documentation link: https://www.apollographql.com/docs/react/data/queries/#executing-queries-manually
When React mounts and renders a component that calls the useQuery hook, Apollo Client automatically executes the specified query. But what if you want to execute a query in response to a different event, such as a user clicking a button?
The useLazyQuery hook is perfect for executing queries in response to events other than component rendering. This hook acts just like useQuery, with one key exception: when useLazyQuery is called, it does not immediately execute its associated query. Instead, it returns a function in its result tuple that you can call whenever you're ready to execute the query
import React, { useState } from 'react';
import { useLazyQuery } from '#apollo/client';
function DelayedQuery() {
const [dog, setDog] = useState(null);
const [getDog, { loading, data }] = useLazyQuery(GET_DOG_PHOTO);
if (loading) return <p>Loading ...</p>;
if (data && data.dog) {
setDog(data.dog);
}
return (
<div>
{dog && <img src={dog.displayImage} />}
<button onClick={() => getDog({ variables: { breed: 'bulldog' } })}>
Click me!
</button>
</div>
);
}
You can either call the query after the await finishes or you can call your query in another useEffect once you update state after your api call. In general, something like this,
const [state, setState] = useState({})
useEffect(async () => {
const result = await get('/api/blah-blah-blah')
// run your query here now that the await has resolved
}, [someDependency])
or
const [state, setState] = useState({})
useEffect(async () => {
const result = await get('/api/blah-blah-blah')
setState(result)
}, [someDependency])
useEffect(() => {
if(state.id) {
// run the query
}
}, [state.someProp])