We Keep Coding

I want to fetch data and display it in a react page

I'm new to reactjs, I want to fetch and display data from my database table in a react page ,i wrote a code following a tutorial but i don't know how to correct it.
This is the data :
and this is the code i'm writing
import React, { useEffect, useState } from 'react';
import axios from 'axios';
function Companies() {
const [companies, setCompanies] = useState(initialState: [])
useEffect( effect: () => {
companydata()
}, deps: [])
const companydata = async () => {
const {data}= await axios.get("http://localhost:5000/api/v1/companies");
setCompanies(data);
}
return (
<div className="companies">
{companies.map(companies => (
<div key={companies.CompanyId}>
<h5>{companies.CompanyName}</h5>
</div>
))}
</div>
);
}
export default Companies;

useEffect( effect: async () => {
await companydata()
}, deps: [])
have you tried adding async and await inside useEffect hook

Try to change your code like this:
import React, { useEffect, useState } from 'react';
import axios from 'axios';
function Companies() {
const [companies, setCompanies] = useState([]);
useEffect(() => {
companydata();
}, []);
const companydata = async () => {
const { data } = await axios.get('http://localhost:5000/api/v1/companies');
setCompanies(data);
};
return (
<div className='companies'>
{companies.map((comp) => (
<div key={comp.CompanyId}>
<h5>{comp.CompanyName}</h5>
</div>
))}
</div>
);
}
export default Companies;

Why does it make a mistake?

The code below is not working. It doesn't see the apikey in parentheses.I couldn't understand what I had to do here. Is it a problem with the hooks structure?
import React, { useEffect } from 'react';
import MovieListing from "../MovieListing/MovieListing";
import movieApi from "../../common/apis/movieApi";
import { APIKey } from "../../common/apis/MovieApiKey"; //the program does not see this
import "./Home.scss";
import { useDispatch } from 'react-redux';
import { addMovies } from '../../features/movies/movieSlice';
const Home = () => {
const dispatch = useDispatch();
useEffect(() => {
const movieText = "Harry";
const fetchMovies = async () => {
const response = await movieApi.get('?apiKey=${APIKey}&s=${movieText}&type=movie')
.catch((err) => { console.log("Err :", err) });
dispatch(addMovies)(response.data); //api key does not see this
};
fetchMovies();
}, []);
return (
<div>
<div className='banner-img'></div>
<MovieListing />
</div>
);
};
export default Home;

Sibling component not re-rerendering on state change (using useEffect, useState and Context)

In my Main.js I create a first global state with a username and a list of users I'm following.
Then, both the Wall component and FollowingSidebar render the list of follows and their messages (plus the messages of the main user).
So far so good. But in a nested component inside FollowingSidebar called FollowingUser I have an onClick to remove a user. My understanding is that, because I change the state, useEffect would take care of the Wall component to re-render it, but nothing happens... I've checked several examples online but nothing has helped my use case so far.
Needless to say I'm not overly experienced with React and Hooks are a bit complex.
The code here:
Main.js:
import React, { useEffect, useState } from "react";
import ReactDom from "react-dom";
import db from "./firebase.js";
// Components
import Header from "./components/Header";
import FollowingSidebar from "./components/FollowingSidebar";
import SearchUsers from "./components/SearchUsers";
import NewMessageTextarea from "./components/NewMessageTextarea";
import Wall from "./components/Wall";
// Context
import StateContext from "./StateContext";
function Main() {
const [mainUser] = useState("uid_MainUser");
const [follows, setFollows] = useState([]);
const setInitialFollows = async () => {
let tempFollows = [mainUser];
const user = await db.collection("users").doc(mainUser).get();
user.data().following.forEach(follow => {
tempFollows.push(follow);
});
setFollows(tempFollows);
};
useEffect(() => {
setInitialFollows();
}, []);
const globalValues = {
mainUserId: mainUser,
followingUsers: follows
};
return (
<StateContext.Provider value={globalValues}>
<Header />
<FollowingSidebar />
<SearchUsers />
<NewMessageTextarea />
<Wall />
</StateContext.Provider>
);
}
ReactDom.render(<Main />, document.getElementById("app"));
if (module.hot) {
module.hot.accept();
}
FollowingSidebar component:
import React, { useState, useEffect, useContext } from "react";
import db from "../firebase.js";
import StateContext from "../StateContext";
import FollowingUser from "./FollowingUser";
export default function FollowingSidebar() {
const { followingUsers } = useContext(StateContext);
const [users, setUsers] = useState(followingUsers);
useEffect(() => {
const readyToRender = Object.values(followingUsers).length > 0;
if (readyToRender) {
db.collection("users")
.where("uid", "in", followingUsers)
.get()
.then(users => {
setUsers(users.docs.map(user => user.data()));
});
}
}, [followingUsers]);
return (
<section id="following">
<div className="window">
<h1 className="window__title">People you follow</h1>
<div className="window__content">
{users.map((user, index) => (
<FollowingUser avatar={user.avatar} username={user.username} uid={user.uid} key={index} />
))}
</div>
</div>
</section>
);
}
FollowingUser component:
import React, { useState, useContext } from "react";
import db from "../firebase.js";
import firebase from "firebase";
import StateContext from "../StateContext";
export default function FollowingUser({ avatar, username, uid }) {
const { mainUserId, followingUsers } = useContext(StateContext);
const [follows, setFollows] = useState(followingUsers);
const removeFollow = e => {
const userElement = e.parentElement;
const userToUnfollow = userElement.getAttribute("data-uid");
db.collection("users")
.doc(mainUserId)
.update({
following: firebase.firestore.FieldValue.arrayRemove(userToUnfollow)
})
.then(() => {
const newFollows = follows.filter(follow => follow !== userToUnfollow);
setFollows(newFollows);
});
userElement.remove();
};
return (
<article data-uid={uid} className="following-user">
<figure className="following-user__avatar">
<img src={avatar} alt="Profile picture" />
</figure>
<h2 className="following-user__username">{username}</h2>
<button>View messages</button>
{uid == mainUserId ? "" : <button onClick={e => removeFollow(e.target)}>Unfollow</button>}
</article>
);
}
Wall component:
import React, { useState, useEffect, useContext } from "react";
import db from "../firebase.js";
import Post from "./Post";
import StateContext from "../StateContext";
export default function Wall() {
const { followingUsers } = useContext(StateContext);
const [posts, setPosts] = useState([]);
useEffect(() => {
console.log(followingUsers);
const readyToRender = Object.values(followingUsers).length > 0;
if (readyToRender) {
db.collection("posts")
.where("user_id", "in", followingUsers)
.orderBy("timestamp", "desc")
.get()
.then(posts => setPosts(posts.docs.map(post => post.data())));
}
}, [followingUsers]);
return (
<section id="wall">
<div className="window">
<h1 className="window__title">Latest messages</h1>
<div className="window__content">
{posts.map((post, index) => (
<Post avatar={post.user_avatar} username={post.username} uid={post.user_id} body={post.body} timestamp={post.timestamp.toDate().toDateString()} key={index} />
))}
</div>
</div>
</section>
);
}
StateContext.js:
import { createContext } from "react";
const StateContext = createContext();
export default StateContext;

The main issue is the setting of state variables in the Main.js file (This data should actually be part of the Context to handle state globally).
Below code would not update our state globally.
const globalValues = {
mainUserId: mainUser,
followingUsers: follows
};
We have to write state in a way that it get's modified on the Global Context level.
So within your Main.js set state like below:
const [globalValues, setGlobalValues] = useState({
mainUserId: "uid_MainUser",
followingUsers: []
});
Also add all your event handlers in the Context Level in Main.js only to avoid prop-drilling and for better working.
CODESAND BOX DEMO: https://codesandbox.io/s/context-api-and-rendereing-issue-uducc
Code Snippet Demo:
import React, { useEffect, useState } from "react";
import FollowingSidebar from "./FollowingSidebar";
import StateContext from "./StateContext";
const url = "https://jsonplaceholder.typicode.com/users";
function App() {
const [globalValues, setGlobalValues] = useState({
mainUserId: "uid_MainUser",
followingUsers: []
});
const getUsers = async (url) => {
const response = await fetch(url);
const data = await response.json();
setGlobalValues({
...globalValues,
followingUsers: data
});
};
// Acts similar to componentDidMount now :) Called only initially
useEffect(() => {
getUsers();
}, []);
const handleClick = (id) => {
console.log(id);
const updatedFollowingUsers = globalValues.followingUsers.filter(
(user) => user.id !== id
);
setGlobalValues({
...globalValues,
followingUsers: updatedFollowingUsers
});
};
return (
<StateContext.Provider value={{ globalValues, handleClick }}>
<FollowingSidebar />
</StateContext.Provider>
);
}
export default App;

Next.JS Redux dispatch not working in getStaticProps()

I am pretty new to Next.JS and I was trying to set up Redux with my Next.JS application. Now my page is supposed to display a list of posts that I am calling in from an API. The page renders perfectly when I'm dispatching from useEffect() to populate the data on to my page, but getStaticProps() or getServerSideProps() are not working whatsoever!
Here is a bit of code that will give you a hint of what I've done so far:
store.js
import { useMemo } from 'react'
import { createStore, applyMiddleware } from 'redux'
import { composeWithDevTools } from 'redux-devtools-extension'
import thunk from 'redux-thunk'
import rootReducer from './reducers/rootReducer'
const initialState = {}
const middlewares = [thunk]
let store
function initStore(preloadedState = initialState) {
return createStore(
rootReducer,
preloadedState,
composeWithDevTools(applyMiddleware(...middlewares))
)
}
export const initializeStore = (preloadedState) => {
let _store = store ?? initStore(preloadedState)
if (preloadedState && store) {
_store = initStore({
...store.getState(),
...preloadedState,
})
store = undefined
}
if (typeof window === 'undefined') return _store
if (!store) store = _store
return _store
}
export function useStore(initialState) {
const store = useMemo(() => initializeStore(initialState), [initialState])
return store
}
action.js
export const fetchPosts = () => async dispatch => {
const res = await axios.get('https://jsonplaceholder.typicode.com/posts')
dispatch({
type: FETCH_POSTS,
payload: res.data
})
}
_app.js
import { Provider } from 'react-redux'
import { createWrapper } from 'next-redux-wrapper'
import { useStore } from '../redux/store'
export default function MyApp({ Component, pageProps }) {
const store = useStore(pageProps.initialReduxState)
return (
<Provider store={store}>
<Component {...pageProps} />
</Provider>
)
}
These are the files that I needed for the basic redux setup. Once my store was set up and I wrapped my app around the Provider, I initially though of using useEffect() hook to populate data on a component that was rendering inside my index.js file.
component.js
import { useEffect } from 'react'
import { useDispatch, useSelector } from 'react-redux'
import { fetchPosts } from '../redux/actions/postsAction'
const Posts = () => {
const dispatch = useDispatch()
const { items } = useSelector(state => state.posts)
useEffect(() => {
dispatch(fetchPosts())
}, [])
return (
<div className="">
<h1>Posts</h1>
{items.map(post => {
return (<div key={post.id}>
<h3>{post.title}</h3>
<p>{post.body}</p>
</div>)
})}
</div>
)
}
export default Posts
This worked perfectly! All my posts were showing up inside the component. The problem occurred when I was trying to achieve the same behaviour with server side rendering (or even SSG). I wanted to populate the data during the pre-render phase but for some reason the items array which is supposed to hold all the data is empty, basically meaning that the disptacher was never called! Here is the piece of code that is bothering me (exactly same as previous code, but this time I'm using getStaticProps() instead of useEffect()):
component.js
import { useEffect } from 'react'
import { useDispatch, useSelector } from 'react-redux'
import { fetchPosts } from '../redux/actions/postsAction'
const Posts = ({ items }) => {
return (
<div className="">
<h1>Posts</h1>
{items.map(post => {
return (<div key={post.id}>
<h3>{post.title}</h3>
<p>{post.body}</p>
</div>)
})}
</div>
)
}
export async function getStaticProps() {
console.log('Props called')
const dispatch = useDispatch()
const { items } = useSelector(state => state.posts)
dispatch(fetchPosts())
console.log(items)
return { props: { items } }
}
export default Posts
By running this, I'm getting an error that items is empty! Please help me, I have no clue what's going wrong here.

Well I fixed this issue myself but I forgot to post an answer for it, my bad!
The problem here really is very simple, hooks don't work outside of a functional component!

I think, inside of getStaticProps just call API or get datas from DB and returns it as props to pages/index.js (any component you want) and inside of this component we can get datas from getStaticProps as props.
Also we can set it as global state using useDispatch of react-redux. After that any component we can call those states using redux mapStateToProps. This is my solution.

This maybe a solution if anyone faced this problem,
import React from 'react';
import {useSelector} from 'react-redux';
import {wrapper} from '../store';
export const getStaticProps = wrapper.getStaticProps(store => ({preview})
=> {
console.log('2. Page.getStaticProps uses the store to dispatch things');
store.dispatch({
type: 'TICK',
payload: 'was set in other page ' + preview,
});
});
// you can also use `connect()` instead of hooks
const Page = () => {
const {tick} = useSelector(state => state);
return <div>{tick}</div>;
};
export default Page;
Got it from here: https://github.com/kirill-konshin/next-redux-wrapper

Unhandled Rejection (TypeError): respo.json is not a function

I'm a beginner in React and stuck with some problem. Getting an issue Unhandled Rejection (TypeError): respo.json is not a function.
import React, { useEffect } from "react";
import { useState } from "react";
import logo from "./logo.svg";
import "./App.css";
import axios from "axios";
function App() {
const { monster, setMonster } = useState([]);
useEffect(() => {
async function fetchData() {
const respo = await axios.get("https://jsonplaceholder.typicode.com/users");
const resp = await respo.data;
setMonster({ monster: [...resp] });
}
fetchData();
}, [monster]);
return (
<div className="App">
<p>{console.log(monster)}</p>
</div>
);
}
export default App;

Use respo.data instead :
Your response has a data key which you need to fetch.
import React, { useEffect } from 'react';
import {useState} from 'react';
import logo from './logo.svg';
import './App.css';
import axios from 'axios';
function App() {
const [monster,setMonster]=useState([]);
useEffect(()=>{
async function fetchData() {
const respo=await axios.get('https://jsonplaceholder.typicode.com/users')
const resp=await respo.data;
setMonster({monster:[...respo]});
}
fetchData();
},[]);
return (
<div className="App">
<p>{console.log(monster)}</p>
</div>
);
}
export default App;
Working code : https://codesandbox.io/s/elated-platform-1itbi?file=/src/App.js

There are two problems in your code:
const {monster,setMonster}=useState([]);
This should be:
const [monster,setMonster] = useState([]);
const resp = await respo.data;
This should be:
const resp = respo.data;
respo.data is not a promise, but already the result of the api.
Note:
To update monster, you have to call setMonster(resp) not setMonster({ monster: resp })

How about just using get/then instead of async/await?
useEffect(()=>{
axios.get('https://jsonplaceholder.typicode.com/users')
.then(response => {
setMonster({
monster:[...response.data]
});
});
}
},[monster]);