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How can i turn this React class component into a functional component?

I'm working on implementing a braintree payment method in my react/mui app. I've found a way that works, but it's in a class component. How can I convert this info a proper functional component?
const BraintreeDropInPaymentMethod = () => {
class Store extends React.Component {
instance;
state = {
clientToken: '<BRAIN TREE KEY>'
};
async componentDidMount() {
const response = await fetch("server.test/client_token");
const clientToken = await response.json();
this.setState({
clientToken,
});
}
async buy() {
const { nonce } = await this.instance.requestPaymentMethod();
await fetch(`server.test/purchase/${nonce}`);
}
render() {
if (!this.state.clientToken) {
return (
<div>
<h1>Loading...</h1>
</div>
);
} else {
return (
<div>
<DropIn
options={{ authorization: this.state.clientToken }}
onInstance={(instance) => (this.instance = instance)}
/>
<Button
variant='contained'
onClick={this.buy.bind(this)}
>
Create Account
</Button>
<Button
variant='outlined'
sx={{ marginLeft: 3 }}
color='warning'
onClick={(e) => handleCancelAccountCreation(e)}
href='/store-front'
>
Cancel
</Button>
</div>
);
}
}
}
const [user, setUser] = useState({})
const handleCancelAccountCreation = (event) => {
setUser({})
document.getElementById('signInBtn').hidden = false
}
return (
<Store/>
)
}
this is my attempt, but I'm coming up short on how I should handle componentDidMount(). I know how to handle useState in some situations, except for this one. Also, how can I handle the 'instance' section in a functional format? thanks.
const BraintreeDropInPaymentMethod = () => {
const [token, setToken] = useState('<BRAIN TREE KEY>')
const [user, setUser] = useState({})
const contactServer = async () => {
const res = await fetch('server.test/client_token')
const clientToken = await res.json()
console.log(clientToken)
setToken(token)
}
const buy = async () => {
const { nonce } = await this.instance.requestPaymentMethod()
await fetch(`server.test/purchase/${nonce}`)
}
const handleCancelAccountCreation = (event) => {
setUser({})
document.getElementById('signInBtn').hidden = false
}
const createAccountOptions = () => {
if (!token) {
return (
<div>
<h1>Loading...</h1>
</div>
) else {
return (
<div>
<DropIn
options={ authorization: {setToken})
onInstance={(instance) => (this.instance = instance)}
/>
<Button
variant="contained'
onClick={buy}
>
Create Account
</Button
variant='outlined'
sx={{ marginLeft: 3 }}
color='warning'
onClick={(e) => handleCancelAccountCreation(e)}
href='/store-front'
>
<Button>
Cancel
</Button>
</div>
)
}
}
}
return(
<>
<createAccountOptions/>
</>
)
}

The functional equivalent of componentDidMount() is the useEffect hook.
In this case you would change this:
async componentDidMount() {
const response = await fetch("server.test/client_token");
const clientToken = await response.json();
this.setState({
clientToken,
});
}
Into something like this:
useEffect(() => {
fetchData();
}, []);
const fetchData = async () => {
const response = await fetch("server.test/client_token");
const clientToken = await response.json();
setState((old) => clientToken);
};
Using the useEffect hook with an empty array as a dependency makes the function in it only run once as the component mounts.

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.
}
};

React map function does not execute when the component is rendered

As you can see below in the dev tools screen shot, the child element does have props. My issue is I cannot get them to appear in the DOM when the component is first rendered. I have to click on the Link element again to re-render the component and only then does the map function work correctly (second screen shot). Another thing is I am using the same code in another component and it works fine. Help!
import React, { useState, useEffect } from 'react'
import firebase from 'firebase';
import NewsLetterListChildComponent from './children/NewsLetterListChildComponent';
import LoadingComponent from '../Loading/LoadingComponent';
function PublicNewsLetterListComponent({ user }) {
const [ newsLetters, setNewsLetters ] = useState([]);
const [ loading, setLoading ] = useState(false);
const [ errors, setErrors ] = useState(false);
useEffect(() => {
let requestCancelled = false;
const getNewsLetters = () => {
setLoading(true);
let newsLetterArray = [];
firebase
.firestore()
.collection('newsLetters')
.get()
.then((querySnapshot) => {
querySnapshot.forEach((doc) => {
const listRef = firebase.storage().ref().child('newsLetterImagesRef/' + doc.id);
listRef
.getDownloadURL()
.then(url => {
newsLetterArray.push({ id: doc.id, data: doc.data(), image: url });
})
.catch(error => console.log(error))
});
});
setNewsLetters(newsLetterArray);
setLoading(false);
};
getNewsLetters();
return () => {
requestCancelled = true;
};
}, []);
const renderContent = () => {
if(loading) {
return <LoadingComponent />
} else {
return <NewsLetterListChildComponent newsLetters={newsLetters} />
}
}
return renderContent();
}
export default PublicNewsLetterListComponent
import React from 'react';
import { ListGroup, ListGroupItem, Row, Col } from 'reactstrap';
function NewsLetterListChildComponent({ newsLetters }) {
return (
<div>
<Row>
<Col md={{size: 6, offset: 3}}>
<ListGroup>
{newsLetters.map((item, index) => {
return (
<ListGroupItem key={index} className="m-1" ><h1>{item.data.title} </h1><img src={item.image} alt={item.data.title} className="thumb-size img-thumbnail float-right" /></ListGroupItem>
);
})}
</ListGroup>
</Col>
</Row>
</div>
)
}
export default NewsLetterListChildComponent;
Initial render and the list group is empty
after the re-render and now the list group is populated

You need to call setNewsLetters when the data is resolved:
const getNewsLetters = async () => {
setLoading(true);
try {
const newsLetters = await firebase
.firestore()
.collection("newsLetters")
.get();
const data = await Promise.all(
newsLetters.docs.map(async (doc) => {
const url = await firebase
.storage()
.ref()
.child("newsLetterImagesRef/" + doc.id)
.getDownloadURL();
return {
id: doc.id,
data: doc.data(),
image: url,
};
})
);
setNewsLetters(data);
} catch (error) {
console.log(error);
} finally {
setLoading(false);
}
};

The useEffect code contains an async request and you are trying to update an array of newsLetters in state even before it will be fetched. Make use of Promise.all and update the data when it is available
useEffect(() => {
let requestCancelled = false;
const getNewsLetters = () => {
setLoading(true);
firebase
.firestore()
.collection('newsLetters')
.get()
.then((querySnapshot) => {
const promises = querySnapshot.map((doc) => {
const listRef = firebase.storage().ref().child('newsLetterImagesRef/' + doc.id);
return listRef
.getDownloadURL()
.then(url => {
return { id: doc.id, data: doc.data(), image: url };
})
.catch(error => console.log(error))
Promise.all(promises).then(newsLetterArray => { setNewsLetters(newsLetterArray);})
});
});
setLoading(false);
};
getNewsLetters();
return () => {
requestCancelled = true;
};
}, []);

If you check newletters with if, your problem will most likely be resolved.
review for detail : https://www.debuggr.io/react-map-of-undefined/
if (newLetters){
newLetters.map(item=> ...)
}

Duplicate keys in React, can't solve the issue. Encountered two children with the same key

Error:
Warning: Encountered two children with the same key, 5e0611d77833da1668feade1. Keys should be unique so that components maintain their identity across updates. Non-unique keys may cause children to be duplicated and/or omitted — the behavior is unsupported and could change in a future version.
Here on this picture https://prnt.sc/qgfymk I have created 2 blogs. Delete button is working fine. I'm sending via axios to HTTP delete request using mongoose and MongoDB as my database.
But when I start to click on like button check what happens. https://prnt.sc/qgg32o
It removes my other blog post and copies one with the same name and id. The issue here is that I have different IDs but somehow when I press LIKE button it gives me another ID.
I'll give you code for both PUT request in backend and frontend for incrementLikes, I really don't know what is going on.
controllers/blogs.js (backend)
blogsRouter.put('/:id', async (request, response, next) => {
const body = request.body
const blogs = {
title:body.title,
author: body.author,
url:body.url,
likes: body.likes
}
try {
const updatedBlog = await Blog.findOneAndUpdate(request.params.id, blogs, {
new: true
})
response.json(updatedBlog.toJSON())
} catch (exception) {
next(exception)
}
})
App.js
import React, { useState, useEffect } from 'react';
import './App.css';
import Blog from './components/Blog';
import LoginForm from './components/LoginForm'
import BlogForm from './components/BlogForm'
import Notification from './components/Notification'
import loginService from './services/login';
import blogService from './services/blogs';
const App = () => {
const [blogs, setBlogs] = useState([])
const [user, setUser] = useState(null)
const [username, setUsername] = useState('')
const [password, setPassword] = useState('')
const [errorMessage, setErrorMessage] = useState(null)
// states for blog creation
const [title, setTitle] = useState('')
const [author, setAuthor] = useState('')
const [url, setUrl] = useState('')
useEffect(() => {
console.log('effect')
blogService
.getAll()
.then(response => {
console.log('promise fulfiled')
setBlogs(response.data)
})
.catch(error => {
console.log('response', error.response)
console.log('error')
})
}, [])
useEffect(() => {
const loggedUserJSON = window.localStorage.getItem('loggedBlogUser')
if (loggedUserJSON) {
const user = JSON.parse(loggedUserJSON)
setUser(user)
blogService.setToken(user.token)
}
}, [])
//put request
***const incrementLike = id => {
const blog = blogs.find(b => b.id === id)
console.log('blog id', blog)
const voteLike = {...blog, likes: blog.likes + 1}
blogService
.update(id, voteLike)
.then(returnedBlog => {
setBlogs(blogs.map(blog => blog.id !== id ? blog : returnedBlog))
})
.catch(error => {
setErrorMessage(
`Blog was already removed from server`
)
setTimeout(() => {
setErrorMessage(null)
}, 5000)
})
}***
//login
const handleLogin = async (e) => {
e.preventDefault()
try {
const user = await loginService.login({username, password})
window.localStorage.setItem('loggedBlogUser', JSON.stringify(user))
setUser(user)
setUsername('')
setPassword('')
console.log('success')
} catch (exception) {
setErrorMessage('wrong credentials')
setTimeout(() => {
setErrorMessage(null)
}, 5000)
console.log('baaad')
}
}
const deleteBlogId = (id) => {
console.log('deleted blog')
blogService
.del(id)
.then(response => {
setBlogs(blogs.filter(blog => blog.id !== id))
})
.catch(error => {
console.log(error.response);
})
}
const handleCreateBlog = async (e) => {
e.preventDefault()
const newBlogs = {
title: title,
author: author,
url: url,
date: new Date()
}
blogService
.create(newBlogs)
.then(returnedBlog => {
setBlogs(blogs.concat(returnedBlog))
setTitle('')
setAuthor('')
setUrl('')
setErrorMessage(`${author} created new blog with name ${title}`)
setTimeout(() => {
setErrorMessage(null)
}, 5000)
})
}
const loginForm = () => {
return (
<div>
<Notification message={errorMessage}/>
<div>
<LoginForm
username={username}
password={password}
handleUsernameChange={({target}) => setUsername(target.value)}
handlePasswordChange={({target}) => setPassword(target.value)}
handleSubmit={handleLogin}
/>
</div>
</div>
)
}
const handleTitleChange = (event) => {
console.log(event.target.value)
setTitle(event.target.value)
}
const blogForm = () => {
return (
<div>
<BlogForm
title={title}
author={author}
url={url}
handleTitleChange={handleTitleChange}
handleAuthorChange={({target}) => setAuthor(target.value)}
handleUrlChange={({target}) => setUrl(target.value)}
onSubmit={handleCreateBlog}
/>
</div>
)
}
const handleLogout = async () => {
window.localStorage.clear()
setUser(null)
}
const logout = () => {
return (
<div><button type="reset" onClick={handleLogout}>Logout</button></div>
)}
const blogList = () => {
return (
<div>
<h2>Blogs</h2>
<p>{user.name} logged in</p>
{logout()}
{blogs.map(blog =>
<Blog
key={blog.id}
deleteBlog={() => deleteBlogId(blog.id)}
blog={blog}
increment={() => incrementLike(blog.id)} />
)}
</div>
)
}
return (
<div className="App">
{user === null ?
loginForm() :
<div>
<Notification message={errorMessage}/>
{blogForm()}
{blogList()}
</div>
}
</div>
);
}
export default App;
Check the incrementLikes function. I think there is some kind of issue. Button for likies are in component called Blog.js
Blog.js
import React from 'react';
const Blog = ({blog, increment, deleteBlog}) => (
<div>
<button onClick={deleteBlog}>Delete</button>
{blog.title}
{blog.author}
{blog.likes}
<button onClick={increment}>Like</button>
</div>
)
export default Blog

While there shouldn't be 2 blogs with the same ID you can fix the issue at hand by replacing the key from blog.id to the index of the post like this.
<div>
<h2>Blogs</h2>
<p>{user.name} logged in</p>
{logout()}
//change
{blogs.map((blog,index) =>
<Blog
//change
key={index}
deleteBlog={() => deleteBlogId(blog.id)}
blog={blog}
increment={() => incrementLike(blog.id)} />
)}
</div>
I added //change to the lines I changed.

You can just use something like uuid for this which will generate a unique ID.
import uuid from "uuid";
<>
<h2>Blogs</h2>
<p>{user.name} logged in</p>
{logout()}
{blogs.map((blog,index) =>
<Blog
key={uuid.v4()}
deleteBlog={() => deleteBlogId(blog.id)}
blog={blog}
increment={() => incrementLike(blog.id)} />
)}
</>