Develop Reference

How to dynamically import a MDX Component in React?

I created an Article component which gets its title through the route parameters like this:
const Article = () => {
const params = useParams()
const dashedTitle = params.title.replace(/ /g, '-')
return (
<article>
<MyMDX />
</article>
);
}
I want to return a MDX file with the same name as the provided title. Simply returning the <MyMDX /> component works fine if I manually import it at the top of the article with import MyMDX from '../markdowns/mymdx.mdx. However, I don't see a way to import this file dynamically, depending on the tile.
Is there a way to do this or could I do this in a better way?

I managed to find a solution to this:
const Article = () => {
const params = useParams()
const [article, setArticle] = useState()
dashedTitle = params.title.replace(/ /g, '-')
useEffect(() => {
import(`../markdowns/${dashedTitle}.mdx`).then(module => {
setArticle(module.default)
}).catch(err => {
console.log(err)
setArticle(undefined)
})
}, [dashedTitle])
return (
<article>
{article ? article : <NotFound />}
</article>
);
}
With useEffect, import the MDX module and then set my article variable to the module's default export (which is exactly the generated JSX component). Thus, I can use it in the return segment in case it's not undefined.
Additionally, I found a similar answer that could help.

My API data is not being rendered with React

I'm learning React by making a Spotify clone and for now, what I'm trying to do is to show Spotify sections such as "last played songs", "top artists" and "top songs" through a component called Body.js.
I get the data from a Spotify official API library created by jmperez in a useEffect hook in the App.js component. Once I get the data from the API, I store it in an object called initialState in a file called reducer.js.
This reducer.js file contains the initial state and the reducer function for a custom hook called useDataLayer.js which is a useContext hook that passes as value a useReducer to all the branches of my program. This way what I do is update the initialState from App.js and access this object through the useDataLayer hook in the different branches of my program (among them the Body component).
The problem I am having now is that it is not rendering the three sections mentioned before in Spotify, but only shows me one which is the "top songs". The weird thing is that for a second it does render the other components as if it was getting the data and rendering but then it updates and they disappear. Please if someone can help me with this problem and explain to me why this happens it would be great.
App.js code
import React, {useState, useEffect} from 'react';
import Login from './components/Login';
import Player from './components/Player';
import { getTokenFromResponse } from './spotify';
import './styles/App.scss';
import SpotifyWebApi from "spotify-web-api-js";
import { library } from '#fortawesome/fontawesome-svg-core';
import { fas } from '#fortawesome/free-solid-svg-icons';
import { fab } from '#fortawesome/free-brands-svg-icons';
import { useDataLayer } from './components/Hooks/useDataLayer';
library.add(fas, fab);
//spotify library instance
const spotify = new SpotifyWebApi();
function App() {
const [token, setToken] = useState(null);
const [{ user }, dispatch] = useDataLayer();
// where I get the necessary data from the api
useEffect(() => {
// function to get access token
let accessToken = getTokenFromResponse();
window.location.hash = '';
if(accessToken){
spotify.setAccessToken(accessToken);
setToken(accessToken);
//FROM HERE I GET THE DATA I NEED
// here I get the data of my user
spotify.getMe().then((data) =>{
dispatch({
type: "GET_USER",
user: date
})
});
spotify.getUserPlaylists().then((data) => {
dispatch({
type: "GET_PLAYLISTS",
playlists: dates
})
});
spotify.getMyTopTracks({limit: 4}).then((data) => {
dispatch({
type: "GET_TOP_TRACKS",
top_tracks:data,
})
});
spotify.getMyRecentlyPlayedTracks({limit: 4}).then((data) => {
dispatch({
type: "RECENTLY_PLAYED",
recently_played: date,
})
});
spotify.getMyTopArtists({limit: 4}).then((data) => {
dispatch({
type: "GET_TOP_ARTISTS",
top_artists: date,
})
});
}
}, [token])
//if the token is valid enter Player.js where Body.js is inside and if not return to the login component
return (
<div className="App">
{ token ? <Player spotify= {spotify} /> : <Login />}
</div>
);
}
export defaultApp;
Body.js code
import React from 'react'
import '../styles/Body.scss'
import { useDataLayer } from "./Hooks/useDataLayer.js";
import { FontAwesomeIcon } from '#fortawesome/react-fontawesome';
function Body({ spotify }) {
//get the properties of the necessary data that I want to display in this component with useDataLayer
const [{ spotify_recommendations, recently_played, top_tracks, top_artists }, dispatch] = useDataLayer();
return (
<div className= "main-body">
<div className= "body-option">
<span className= "see-more">See All</span>
<FontAwesomeIcon icon={['fas', 'arrow-right']} />
<div>
{
//to show the image and info of the track
recently_played?.items.map((item, index) =>{
return (
<div className= "track" key= {index}>
<img src= {item.track.album.images[1].url} alt= "recently played track"></img>
<div className= "track-data">
<h3>{item.track.name}</h3>
<p>{item.track.artists.map(artist => artist.name).join(", ")}</p>
</div>
</div>
)
})
}
</div>
</div>
<div className= "body-option">
<span className= "see-more">See All</span>
<FontAwesomeIcon icon={['fas', 'arrow-right']} />
<div>
{
//to show the image and info of the track
top_tracks?.items.map((topArtist, index) => {
return (
<div className= "track" key= {index}>
<img src= {topArtist.album.images[1].url} alt= "recently played track"></img>
<div className= "track-data">
<h3>{topArtist.name}</h3>
<p>{topArtist.artists.map(artist => artist.name).join(", ")}</p>
</div>
</div>
)
})
}
</div>
</div>
<div className= "body-option">
<span className= "see-more">See All</span>
<FontAwesomeIcon icon={['fas', 'arrow-right']} />
<div>
{
//to show the image and info of the artist
top_artists?.items.map((topTrack, index) => {
return (
<div className= "track" key= {index}>
<img src= {topTrack.images[1].url} alt= "recently played track"></img>
<div className= "track-data">
<h3>{topTrack.name}</h3>
<p>{topTrack.genres.join(", ")}</p>
</div>
</div>
)
})
}
</div>
</div>
</div>
)
}
export default Body
Code of my custom hook useDataLayer.js
import React, {useContext, createContext, useReducer} from 'react'
let DataContext = createContext();
export function DataLayer({reducer, initialState, children}) {
return (
<DataContext.Provider value= {useReducer(reducer, initialState)}>
{children}
</DataContext.Provider>
)
}
export let useDataLayer = () => useContext(DataContext);
SideBar.js: the component where i display the user's playlist
import React from 'react';
import { FontAwesomeIcon } from '#fortawesome/react-fontawesome';
import { useDataLayer } from './Hooks/useDataLayer.js';
import '../styles/SideBar.scss';
function SideBar({ spotify }){
const [{ playlists }, dispatch] = useDataLayer();
return (
<div className= "side-bar">
<div className= "side-bar-options">
<div className= "spotify-logo">
<FontAwesomeIcon icon={['fab', 'spotify']} size= "3x"/>
<h1 className= "spotify-title">Spotify</h1>
</div>
<a className= "option" href= "./Player.js">
<FontAwesomeIcon icon={['fas', 'home']} />
<p className= "option-title" >Inicio</p>
</a>
<a className= "option" href= "./Player.js">
<FontAwesomeIcon icon={['fas', 'search']} />
<p className= "option-title">Buscar</p>
</a>
<a className= "option" href= "./Player.js">
<FontAwesomeIcon icon={['fas', 'headphones']} />
<p className= "option-title" >Tu Biblioteca</p>
</a>
</div>
<p className= "playlist-title">PLAYLISTS</p>
<div className= "playlists">
{
playlists?.items?.map(
(list, index) =>
<p className="playlists-option"
key={index}
>
{list.name}
</p>
)
}
</div>
</div>
)
}
export default SideBar;
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
Player.js
import React from 'react';
import "../styles/Player.scss";
import SideBar from "./SideBar.js";
import Body from "./Body.js";
function Player({spotify}) {
return (
<div className= "player-container">
<div className= "player_body">
<SideBar spotify= {spotify} />
<Body spotify= {spotify} />
</div>
</div>
)
}
export default Player;
spotify.js: the code where i get the token from the URL
const authEndpoint = "https://accounts.spotify.com/authorize";
const clientId = '84c134b175474ddabeef0e0b3f9cb389'
const redirectUri = 'http://localhost:3000/'
const scopes = [
"user-read-currently-playing",
"user-read-recently-played",
"user-read-playback-state",
"user-top-read",
"user-modify-playback-state",
"user-follow-modify",
"user-follow-read",
"playlist-modify-public",
"playlist-modify-private",
"playlist-read-private",
"playlist-read-collaborative"
];
//obtain acces token from url
export const getTokenFromResponse = () => {
let params = new URLSearchParams(window.location.hash.substring(1));
let token = params.get("access_token");
return token;
};
//acces url
const accessUrl = `${authEndpoint}?client_id=${clientId}&redirect_uri=${redirectUri}&scope=${scopes.join("%20")}&response_type=token&show_dialog=true`;
export default accessUrl;
Thank you very much for your time and attention.

By the look of it, your useEffect hook is being called twice in quick succession. It has the dependency of token, which starts as null for your first render. Inside the hook you then read the accessToken and set the state for it to your token. Doing this will trigger another render because the dependency changed from null to the value of your access token.
I would suggest to simply remove token from your useEffect dependency array (so that your hook acts as an "on mounted" event) and see if that gets you the desired effect. You should eventually move the getTokenFromResponse outside the hook, assuming it is not available on first render, as I'm just guessing it is immediately available.
Post comments, it might be better to separate your initializing code into a useEffect that only runs once, when the component is first mounted. This way, as I now suspect getTokenFromResponse() returns a new Object every call, you only need to call it once. Note, if it returns a Promise, this won't work, so you should verify this first before trying.
To better illustrate my point, I've put it in code with some comments:
useEffect(() => {
setToken(getTokenFromResponse());
// this only needs to happen once
window.location.hash = '';
}, []; // <- empty dependency array will only run once, on mount
useEffect(() => {
// out of the 2 times this will be called,
// it should only pass this condition on the last/2nd
if(token){
spotify.setAccessToken(token);
//FROM HERE I GET THE DATA I NEED
// here I get the data of my user
spotify.getMe().then((data) =>{
dispatch({
type: "GET_USER",
user: date
})
});
spotify.getUserPlaylists().then((data) => {
dispatch({
type: "GET_PLAYLISTS",
playlists: dates
})
});
spotify.getMyTopTracks({limit: 4}).then((data) => {
dispatch({
type: "GET_TOP_TRACKS",
top_tracks:data,
})
});
spotify.getMyRecentlyPlayedTracks({limit: 4}).then((data) => {
dispatch({
type: "RECENTLY_PLAYED",
recently_played: date,
})
});
spotify.getMyTopArtists({limit: 4}).then((data) => {
dispatch({
type: "GET_TOP_ARTISTS",
top_artists: date,
})
});
}
// this will trigger the effect any time token changes,
// which should now only be twice:
// 1st at it's default state value (null)
// 2nd after the previous useEffect sets its state
}, [token]);
Hope that helps but, if it's a promise, you'll need to handle it according (suggestion: moving the setToken into the then)
Good luck!

map function not rendering jsx? Error: Objects are not valid as a React child

I'm working on the comments feature of my assignment. I'm trying to display the author name of the comments from my object. However, my map function doesnt seem to be working as whenever I click the button I get an error saying Error: Objects are not valid as a React child (found: object with keys {roles, _id, username, email, password, __v}). If you meant to render a collection of children, use an array instead.
Reviews,js
import React, {useState, useRef} from 'react';
import Axios from 'axios';
import {Button, Input} from 'antd';
import authService from '../../services/auth.service'
import authHeader from '../../services/auth-header';
import FirstReview from './FirstReview';
const {TextArea} = Input;
const Reviews = (props) => {
const currentUser = authService.getCurrentUser();
const [review, setReview] = useState('');
const handleChange = (e) => {
setReview(e.target.value)
}
const onSubmit = (e) => {
e.preventDefault();
const variables = {
movieId: props.movieId,
content: review,
author: currentUser.id,
reviewId: props.reviewId,
}
Axios.post('http://localhost:8080/api/review/addReview', variables,{ headers: authHeader()})
.then(response=> {
if(response.data.success) {
setReview("")
props.refreshFunction(response.data.result)
} else {
alert('Failed to save review')
}
})
}
return (
<div>
<p>Reviews</p>
{props.reviewList && props.reviewList.map((review, index) => (
(!review.responseTo &&
<React.Fragment key={review._id}>
<FirstReview review={review} movieId={props.movieId} refreshFunction={props.refreshFunctions}/>
</React.Fragment>
)))}
<form style={{display: 'flex'}} onSubmit>
<TextArea
style={{width: '100%', borderRadius: '5px'}}
placeholder = "leave a review"
value={review}
onChange={handleChange}
/>
<Button style = {{width: '20%', height: '52px'}} onClick={onSubmit}></Button>
</form>
</div>
);
};
export default Reviews
FirstReview.js
import React from 'react'
import { Button, Comment, Form, Header, TextArea } from 'semantic-ui-react'
const action = [
<span onClick key="comment-basic-reply-to">reply</span>
]
function FirstReview(props) {
// const authorName = props.review.author;
// const author = {
// authorName: authorName
// }
return (
<div>
<Comment>
<Comment.Content>
<Comment.Author as='a'> {props.review.author} </Comment.Author>
</Comment.Content>
</Comment>
<form style={{display: 'flex'}} onSubmit>
<TextArea
style={{width: '100%', borderRadius: '5px'}}
placeholder = "leave a review"
value={Comment}
onChange
/>
</form>
</div>
)
}
export default FirstReview
I have a file called movie-info.component which has a container which uses the Review component.
<Container2>
<Reviews refreshFunction={updateReview} reviewList={reviewList} movieId={movieInfo?.id}/>
</Container2>

This is an assignment question so I can't give you the full answer, but what your error message means is that you're taking an object somewhat this:
let thing = { first_name: "Tom", last_name: "Jack" }
and then doing this:
<p>{thing}</p>
and although you might be expecting to see "Tom Jack" in the above, you will get the error that you've suggested because React is unable to turn the object into anything that would meaningfully fit inside a p tag.
Do this instead:
<p>{thing.first_name + thing.last_name}</p>
which is specific enough for React to validly render.

Draft-js JSON to EditorState does not update

So, I used Draft-js to create blog posts. When a user creates a post, the data is converted to a string and sent to the server to be saved. I converted the draft-js EditorState like this:
JSON.stringify(convertToRaw(editorState.getCurrentContent())).
Now, I want to add an edit post function. To do this, I get the string data from the server (in the exact same format as described above), and I try to create an editorState from it like this:
let data = convertFromRaw(res.data['postContent'])
setEditorState(EditorState.createWithContent(data))
This seems to work as when I run console.log(convertToRaw(editorState.getCurrentContent())) I can see that the server data is in the editorState. However, nothing is displayed inside of the editor. My question: How do I show the data to the user inside the editor, and make it editable? As in, the user can see the post and modify parts of it.
Here is a screenshot of what I get (as you can see, the title is there but the editor is empty when it should say "Test data!"):
Here is my full code:
import React, {useEffect, useState} from 'react'
import { EditorState, convertToRaw, convertFromRaw } from 'draft-js'
import { useLocation } from 'react-router-dom';
import { Editor } from 'react-draft-wysiwyg';
import 'react-draft-wysiwyg/dist/react-draft-wysiwyg.css';
import './css/CreateBlog.css'
import ApiClient from '../util/ApiClient';
// submit the blog post
const submitPage = async (data, postTitle, setPosted, setPostFailed) => {
const content = JSON.stringify(convertToRaw(data));
ApiClient.post("/blog/handle-blog", {"postTitle": postTitle,"postContent": content})
.then((res) => {
console.log(res)
// there was no error
if(res.status === 201) {
setPosted("Your blog has been posted.")
setPostFailed(false)
} else {
setPosted("There was an error.")
setPostFailed(true)
}
})
}
// if this is an edit
const getPostData = async (postID, setEditorState, setPostTitle) => {
const res = await ApiClient.get(`/blog/get-blog/${postID}`)
// set the title and data
setPostTitle(res.data['postTitle'])
setEditorState(EditorState.createWithContent(convertFromRaw(res.data['postContent']))) // set the editorState data
}
export default function CreateBlogpost() {
const location = useLocation();
const postID = location.state?.id; // get the ID if there is one
const [editorState, setEditorState] = useState(null);
const [postTitle, setPostTitle] = useState("");
const [posted, setPosted] = useState(""); // the error/success message
const [postFailed, setPostFailed] = useState(false); // has the blog successfully been posted?
// handle the post button click
const handleSubmit = async (e) => {
e.preventDefault();
// check the post contains data
if(editorState === EditorState.createEmpty() || postTitle == "") {
setPosted("Please add some content to your post.")
setPostFailed(true)
return;
}
const data = editorState.getCurrentContent()
await submitPage(data, postTitle, setPosted, setPostFailed);
}
useEffect(() => {
// if the state has an ID, then you're editing a post
if(postID) {
getPostData(postID, setEditorState, setPostTitle)
}
}, [])
return(
<div className="create-blog">
<div className="create-blog-text m-2 mb-3">
<h1>{postID ? "Edit" : "Create"} a blog post</h1>
</div>
<div className="d-flex">
<h3 className="m-2">Title: </h3>
<input value={postTitle} type="text" id="fname" className="m-2" onChange={e=>setPostTitle(e.target.value)} />
<p className="m-2">Please note: if you want to upload a photo, upload it to an image sharing site like imgur and then link the image.</p>
</div>
<div className="editor-container mb-3 ml-2 mr-2"
style={{ border: "1px solid black", minHeight: "6em", cursor: "text" }}
>
<Editor value={editorState} onEditorStateChange={setEditorState} />
</div>
<button className="button-3 m-2" onClick={(e) => handleSubmit(e)}>
{postID ? "Edit" : // if there is a postID, then you are editing the post
"Post" }
</button>
{/* <button className="button-3 m-2" onClick={(e) => handleSubmit(e)}>Save as draft</button> */}
<h4 style={{ color: postFailed ? 'red' : 'green'}}>{posted}</h4>
</div>
)
}

change
<Editor
value={editorState}
onEditorStateChange={setEditorState}
/>
to
<Editor
editorState={editorState}
onEditorStateChange={setEditorState}
/>

Here is the working version in sandbox. I commented the useLocation and ApiClient calls so perhaps those are the culprit. Also your res.data['postContent'] looks like a JSON. If so, then you need to JSON.parse(res.data['postContent']).

Refactoring Search component from App js to Search js

So im following along with a book "The Road To React" By: Robin Wieruch. The book has you do everything inside the App.js file...which is extremely disappointing because this is obviously terrible practice. Anyway, ive extracted everything else to their own component files and i cant figure out how to extract the search to its own file. Ive attached an img showing the folder structure.
In App.js im trying to extract everything, leaving a return that returns the components like it should be. As it is the App.js file looks like this:
import React, { useState } from 'react';
import './App.css';
import Greeting from '../Greeting/Greeting';
import Search from '../Search/Search';
import List from '../List/List';
const useSemiPersistentState = (key, initialState) => {
const [value, setValue] = React.useState(
localStorage.getItem(key) || initialState
);
React.useEffect(() => {
localStorage.setItem(key, value);
}, [value, key]);
return [value, setValue]
};
// App component
const App = () => {
const stories = [
{
title: 'React',
url: 'https://reactjs.org/',
author: 'Jordan Walke',
num_comments: 3,
points: 4,
objectID: 0,
},
{
title: 'Redux',
url: 'https://redux.js.org/',
author: 'Dan Abramov, Andrew Clark',
num_comments: 2,
points: 5,
objectID: 1,
},
];
// Set state on searchTerm, setSearchTerm with custom hook
const [searchTerm, setSearchTerm] = useSemiPersistentState(
'search',
'React'
);
// Get the value of search input
const handleSearch = (event) => {
setSearchTerm(event.target.value);
};
// Check if user input matches stories array
// toLowerCase() both values
const searchedStories = stories.filter((story) => story.title.toLowerCase().includes(searchTerm.toLowerCase())
);
// Render
return (
<div className="App">
<Greeting name="Colin" age="28" occupation="Front-end developer" />
<InputWithLabel
id="search"
value={searchTerm}
isFocused
onInputChange={handleSearch}
>
<strong>Search:</strong>
</InputWithLabel>
<hr />
<List list={searchedStories} />
</div>
);
}
// Search bar
// Destructure props search, onSearch
const InputWithLabel = ({ id, value, type = "text", onInputChange, isFocused, children, }) => {
const inputRef = React.useRef();
React.useEffect(() => {
if (isFocused && inputRef.current) {
inputRef.current.focus();
}
}, [isFocused]);
return (
<>
<label htmlFor={id}>{children}</label>
<input
ref={inputRef}
id={id}
type={type}
value={value}
autoFocus={isFocused}
onChange={onInputChange}
/>
</>
)
}
export default App;
The List component which is a parent of the Item component looks like so:
import React from 'react';
import Item from '../Item/Item';
function List({ list }) {
return (
<ul>
{list.map(({ objectID, ...item }) => (
<Item key={objectID} {...item} />
))}
</ul>
);
}
export default List;
The Item component looks like so:
import React from 'react';
function Item({ title, url, author, num_comments, points }) {
return (
<div>
<li>
<span>
<a href={url}>{title}</a>
</span>
<span> {author}</span>
<span> {num_comments} comments,</span>
<span> {points} points.</span>
</li>
</div>
);
}
export default Item;
The Greeting Component and Helpers folder are unrelated in any way so i wont post them.
Just as a note all of the code in here works... and at the time im not really interested in refactoring this unless you care to. Im just trying to extract all of that nonsense that relates to what should be a separate Search component out of App.js and into Search.js. Have been trying and ive hit a wall with this as im still new with react.
Here are the errors shown once i move all of the Search content related code from App.js to Search.js and attempt to import to the Search component into App.js
****Failed to compile****
src/Components/App/App.js
Line 60:8: 'InputWithLabel' is not defined react/jsx-no-undef
Line 62:16: 'searchTerm' is not defined no-undef
Line 64:24: 'handleSearch' is not defined no-undef
Line 69:19: 'searchedStories' is not defined no-undef
Search for the keywords to learn more about each error.