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Keep checkbox checked after refreshing the page

I'm trying to fetch all objects from the favorites array and set the checkbox to checked
I've checked online and tried using the localStorage for that yet nothing works and the values aren't saved after refreshing.
Would appreciate any help!
Selected Book Component :
import React, { useEffect, useState } from 'react';
import { bookService } from '../service/book.service';
export const SelectedBook = ({ selectedBook, setFavorites, favorites, removeFavorite }) => {
const onHandleFavorite = (book, e) => {
if (e.currentTarget.checked) {
setFavorites([...favorites, book]);
bookService.addFavorite(book);
} else {
removeFavorite(book);
}
};
const isFavorite = () => {
if (!favorites.includes(selectedBook)) {
return false;
} else {
return true;
}
};
return (
<div className='selected-book-container'>
<input type='checkbox' checked={isFavorite()} onChange={(e) => onHandleFavorite(selectedBook, e)} />
<div className='title'>{selectedBook?.title}</div>
</div>
);
};
Book Page component :
import React, { useEffect, useState } from 'react';
import { bookService } from '../service/book.service.js';
import { BookList } from '../cmps/BookList';
import { SelectedBook } from '../cmps/SelectedBook.jsx';
import { utilService } from '../service/util.service';
export const BookPage = () => {
const [books, setBooks] = useState([]);
const [favorites, setFavorites] = useState([]);
const [index, setIndex] = useState(0);
const [selectedBook, setSelectedBook] = useState();
useEffect(() => {
bookService.favoriteQuery().then((res) => {
setFavorites(res);
});
}, []);
useEffect(() => {
bookService.query().then((res) => {
setBooks(res);
setSelectedBook(res[0]);
});
}, []);
document.onkeydown = checkKey;
function checkKey(e) {
e = e || window.event;
if (e.keyCode == '37') {
if (index === 0) return;
setIndex(index - 1);
} else if (e.keyCode == '39') {
if (index >= books.length - 1) return;
setIndex(index + 1);
}
}
useEffect(() => {
setSelectedBook(books[index]);
}, [index]);
const removeFavorite = (book) => {
setFavorites(favorites.filter((favorite) => favorite.id !== book.id));
bookService.removeFavorite(selectedBook);
};
return (
<div>
<div className='main-container main-layout'>
<div className='second'>
<SelectedBook
selectedBook={selectedBook}
setFavorites={setFavorites}
favorites={favorites}
removeFavorite={removeFavorite}
/>
<BookList books={favorites} removeFavorite={removeFavorite} />
</div>
</div>
<div className='footer-container'>
<section className='footer'>Footer</section>
</div>
</div>
);
};
Service :
async function favoriteQuery() {
try {
let favorites = await _loadeFavoriteFromStorage();
if (!favorites) return (favorites = []);
return favorites;
} catch (err) {
console.log('cannot load favorites', err);
}
}
function _loadeFavoriteFromStorage() {
return storageService.loadFromStorage(STORAGE_FAVORITE_KEY);
}
Storage Service :
export const storageService = {
loadFromStorage,
saveToStorage
}
function saveToStorage(key, val) {
localStorage.setItem(key, JSON.stringify(val))
}
function loadFromStorage(key) {
var val = localStorage.getItem(key)
return JSON.parse(val)
}
thanks for any kind of help

You're not updating localstorage each time that checked is being changed. You're calling setFavorites with a new set of favorites but this is just changing state. I would suggest creating a function within the book page component which does
function changeFavorite(book, checked){
saveToStorage(book?, checked)
rerender()
}
and having rerender set the state of favorites to whatever is in localstorage to ensure that you have a single source of truth which is found in localstorage and that you change that and not anything else
I'll just add
if (!favorites.includes(selectedBook)) {
return false;
} else {
return true;
}
};
Could really look like
const isFavorite () => favorites.includes(selectedBook)
I also didn't quite understand how you're doing about storing the books in object storage. You should probably have an id of some sorts which you use to save favorite information with

useEffect not firing after updating the component's state

I am making a simple e-commerce website but I've ran into an issue where useEffect() won't fire after making a state change. This code snippet I'll include is for the "shopping cart" of the website and uses localStorage to store all items in the cart. My state will change when quantity changes in the QuantChange() function but will not trigger useEffect(). When I refresh the page after changing an item's quantity, the new quantity won't persist and the old quantity is shown instead. What am I doing wrong? Thanks in advance.
import React, { useState, useEffect } from 'react';
import { SetQuantity } from '../utils/Variables';
import { CartItem } from './CartItem';
const CartView = () => {
const [state, setState] = useState(
JSON.parse(localStorage.getItem('cart-items'))
? JSON.parse(localStorage.getItem('cart-items'))
: []
);
useEffect(() => {
console.log('Updating!');
updateLocalStorage();
});
const updateLocalStorage = () => {
localStorage.setItem('cart-items', JSON.stringify(state));
};
const quantChange = (event) => {
setState((prevState) => {
prevState.forEach((item, index) => {
if (item._id === event.target.id) {
item.quantity = SetQuantity(parseInt(event.target.value), 0);
prevState[index] = item;
}
});
return prevState;
});
};
const removeItem = (id) => {
setState((prevState) => prevState.filter((item) => item._id != id));
};
// Fragments need keys too when they are nested.
return (
<>
{state.length > 0 ? (
state.map((item) => (
<CartItem
key={item._id}
ID={item._id}
name={item.name}
quantity={item.quantity}
changeQuant={quantChange}
delete={removeItem}
/>
))
) : (
<h1 className="text-center">Cart is Empty</h1>
)}
</>
);
};
export default CartView;
import React, { Fragment } from 'react';
import { MAX_QUANTITY, MIN_QUANTITY } from '../utils/Variables';
export const CartItem = (props) => {
return (
<>
<h1>{props.name}</h1>
<input
id={props.ID}
type="number"
max={MAX_QUANTITY}
min={MIN_QUANTITY}
defaultValue={props.quantity}
onChange={props.changeQuant}
/>
<button onClick={() => props.delete(props.ID)} value="Remove">
Remove
</button>
</>
);
};
export const MIN_QUANTITY = 1;
export const MAX_QUANTITY = 99;
// Makes sure the quantity is between MIN and MAX
export function SetQuantity(currQuant, Increment) {
if (Increment >= 0) {
if (currQuant >= MAX_QUANTITY || (currQuant + Increment) > MAX_QUANTITY) {
return MAX_QUANTITY;
} else {
return currQuant + Increment;
}
} else {
if (currQuant <= MIN_QUANTITY || (currQuant + Increment) < MIN_QUANTITY) {
return MIN_QUANTITY;
} else {
return currQuant + Increment;
}
}
}

You are not returning new state, you are forEach'ing over it and mutating the existing state and returning the current state. Map the previous state to the next state, and for the matching item by id create and return a new item object reference.
const quantChange = (event) => {
const { id, value } = event.target;
setState((prevState) => {
return prevState.map((item) => {
if (item._id === id) {
return {
...item,
quantity: SetQuantity(parseInt(value), 0)
};
}
return item;
});
});
};
Then for any useEffect hook callbacks you want triggered by this updated state need to have the state as a dependency.
useEffect(() => {
console.log('Updating!');
updateLocalStorage();
}, [state]);

"Unhandled Rejection (Error): Too many re-renders..." because I'm setting state within a loop?

I'm getting a "Unhandled Rejection (Error): Too many re-renders. React limits the number of renders to prevent an infinite loop." message for the following code. Not sure what is causing this issue.
I think it's because I'm calling the setNewNotifications(combineLikesCommentsNotifications) within the users.map loop. But if I move setNewNotifications(combineLikesCommentsNotifications) outside of the loop, it can no longer read likeNewNotifications / commentNewNotifications. What is the best approach to this?
Code below, for context, users returns:
const users = [
{
handle: "BEAR6",
posts: undefined,
uid: "ckB4dhBkWfXIfI6M7npIPvhWYwq1"
},
{
handle: "BEAR5",
posts: [
{
comment: false,
handle: "BEAR5",
key: "-Mmx7w7cTl-x2yGMi9uS",
like: {
Mn4QEBNhiPOUJPBCwWO: {
like_notification: false,
postId: "-Mmx7w7cTl-x2yGMi9uS",
postUserId: "rFomhOCGJFV8OcvwDGH6v9pIXIE3",
uid: "ckB4dhBkWfXIfI6M7npIPvhWYwq1",
userLikeHandle: "BEAR6"
}},
post_date: 1635260810805,
title: "hello"
},
{
comment: false,
comments_text: {0: {
comment_date: 1635399828675,
comment_notification: false,
commenter_comment: "hi1",
commenter_handle: "BEAR6",
commenter_uid: "ckB4dhBkWfXIfI6M7npIPvhWYwq1",
key: "-Mn4QF1zT5O_pLRPqi8q"
}},
handle: "BEAR5",
key: "-MmxOs0qmFiU9gpspEPb",
like: {
Mn4QDCOrObhcefvFhwP: {
like_notification: false,
postId: "-MmxOs0qmFiU9gpspEPb",
postUserId: "rFomhOCGJFV8OcvwDGH6v9pIXIE3",
uid: "ckB4dhBkWfXIfI6M7npIPvhWYwq1",
userLikeHandle: "BEAR6"},
Mn4QKEk95YG73qkFsWc: {
postId: "-MmxOs0qmFiU9gpspEPb",
postUserId: "rFomhOCGJFV8OcvwDGH6v9pIXIE3",
uid: "rFomhOCGJFV8OcvwDGH6v9pIXIE3",
userLikeHandle: "BEAR5"
}},
post_date: 1635265250442,
title: "hi"
}
],
uid: "rFomhOCGJFV8OcvwDGH6v9pIXIE3"
}
]
Code
import React, { useState } from 'react';
import { useSelector, useDispatch } from 'react-redux';
export default function Notifications() {
const [newNotifications, setNewNotifications] = useState('')
const users = useSelector(state => state.users)
return users.map((post) => {
if(post.posts){
return post.posts.map((postContent) => {
const likes = postContent.like ? Object.values(postContent.like) : null
const comments = postContent.comments_text ? Object.values(postContent.comments_text) : null
const likeNewNotifications = likes ? likes.filter(post => {
return post.like_notification === false
} ) : null
const commentNewNotifications = comments ? comments.filter(post => {
return post.comment_notification === false
} ) : null
const combineLikesCommentsNotifications = likeNewNotifications.concat(commentNewNotifications)
setNewNotifications(combineLikesCommentsNotifications)
}
)
}
return (
<div>
<p>
{newNotifications}
</p>
</div>
);
}
)
}

There are multiple errors. But lets face it step by step.
I'll copy and paste your code, but with extra comments, to let you know where I'm referencing:
import React, { useState } from 'react';
import { useSelector, useDispatch } from 'react-redux';
export default function Notifications() {
const [newNotifications, setNewNotifications] = useState('')
const users = useSelector(state => state.users)
// Step 0: I guess the error is because this users.map is running everytime (with any update in the component. So, when you set a new state, it'll render again. So, you have to do this, probably 2 times: on mount and after one update.
// Step 1: You're using users.map but it returns a new array. My recommendation would be: use users.forEach instead.
return users.map((post) => {
if(post.posts){
return post.posts.map((postContent) => {
const likes = postContent.like ? Object.values(postContent.like) : null
const comments = postContent.comments_text ? Object.values(postContent.comments_text) : null
const likeNewNotifications = likes ? likes.filter(post => {
return post.like_notification === false
} ) : null
const commentNewNotifications = comments ? comments.filter(post => {
return post.comment_notification === false
} ) : null
const combineLikesCommentsNotifications = likeNewNotifications.concat(commentNewNotifications)
setNewNotifications(combineLikesCommentsNotifications)
}
)
}
return (
<div>
<p>
{newNotifications}
</p>
</div>
);
}
)
}
(Read Step 0 and Step 1 as comments in the code)
Also, about:
But if I move setNewNotifications(combineLikesCommentsNotifications) outside of the loop, it can no longer read likeNewNotifications / commentNewNotifications. What is the best approach to this?
You can do
Step 3: To be able to do that, you can use let, set one variable in the parent of the loop and update the value inside the loop (or if you have an array can push even if it's const). it'd be like:
function foo() {
const users = [{}, {}, {}, {}];
const usersWithEvenId = [];
users.forEach(user => {
if (user.id % 2 === 0) {
usersWithEvenId.push(user)
}
})
}
Taking in consideration these 3 steps the resulted code would be like:
import React, { useState, useEffect} from 'react';
import { useSelector, useDispatch } from 'react-redux';
export default function Notifications() {
const [newNotifications, setNewNotifications] = useState('');
const users = useSelector(state => state.users);
// Function to get new posts
const getNewPosts = () => {
const notifications = [];
users.forEach((user) => {
if (user.posts) {
posts.forEach((post) => {
// Your logic;
notifications.push(newNotifications)
})
}
});
setNewNotifications(notifications);
};
// Run to get newPosts on mount (but also in any other moment)
useEffect(() => {
getNewPosts();
}, [])
return (
<div>
<p>
{newNotifications}
</p>
</div>
);
}

Maybe you can write the code like this:
import React, { useState } from "react";
import { useSelector, useDispatch } from "react-redux";
export default function Notifications() {
const users = useSelector((state) => state.users);
const combineLikesCommentsNotifications = users.map((post) => {
if (post.posts) {
return post.posts.map((postContent) => {
const likes = postContent.like ? Object.values(postContent.like) : null;
const comments = postContent.comments_text
? Object.values(postContent.comments_text)
: null;
const likeNewNotifications = likes
? likes.filter((post) => {
return post.like_notification === false;
})
: null;
const commentNewNotifications = comments
? comments.filter((post) => {
return post.comment_notification === false;
})
: null;
const combineLikesCommentsNotifications = likeNewNotifications.concat(
commentNewNotifications
);
setNewNotifications(combineLikesCommentsNotifications);
});
}else{
return [];
}
})
const [newNotifications, setNewNotifications] = useState(combineLikesCommentsNotifications);
return (
<div>
<p>{newNotifications}</p>
</div>
); ;
}

React converting class into function component issues

I am trying to use React Scheduler with my shifts database. The current state after trying to use hooks instead of class is that I cannot edit any field in the form. I have deleted some of the code to make it cleaner, for now I am trying only to add a shift.
React Scheduler original code:
import * as React from 'react';
import Paper from '#material-ui/core/Paper';
import { ViewState, EditingState } from '#devexpress/dx-react-scheduler';
import {
Scheduler,
Appointments,
AppointmentForm,
AppointmentTooltip,
WeekView,
} from '#devexpress/dx-react-scheduler-material-ui';
import { appointments } from '../../../demo-data/appointments';
export default class Demo extends React.PureComponent {
constructor(props) {
super(props);
this.state = {
data: appointments,
currentDate: '2018-06-27',
addedAppointment: {},
appointmentChanges: {},
editingAppointment: undefined,
};
this.commitChanges = this.commitChanges.bind(this);
this.changeAddedAppointment = this.changeAddedAppointment.bind(this);
this.changeAppointmentChanges = this.changeAppointmentChanges.bind(this);
this.changeEditingAppointment = this.changeEditingAppointment.bind(this);
}
changeAddedAppointment(addedAppointment) {
this.setState({ addedAppointment });
}
changeAppointmentChanges(appointmentChanges) {
this.setState({ appointmentChanges });
}
changeEditingAppointment(editingAppointment) {
this.setState({ editingAppointment });
}
commitChanges({ added, changed, deleted }) {
this.setState((state) => {
let { data } = state;
if (added) {
const startingAddedId = data.length > 0 ? data[data.length - 1].id + 1 : 0;
data = [...data, { id: startingAddedId, ...added }];
}
return { data };
});
}
render() {
const {
currentDate, data, addedAppointment, appointmentChanges, editingAppointment,
} = this.state;
return (
<Paper>
<Scheduler
data={data}
height={660}
>
<ViewState
currentDate={currentDate}
/>
<EditingState
onCommitChanges={this.commitChanges}
addedAppointment={addedAppointment}
onAddedAppointmentChange={this.changeAddedAppointment}
appointmentChanges={appointmentChanges}
onAppointmentChangesChange={this.changeAppointmentChanges}
editingAppointment={editingAppointment}
onEditingAppointmentChange={this.changeEditingAppointment}
/>
<WeekView
startDayHour={9}
endDayHour={17}
/>
<Appointments />
<AppointmentTooltip
showOpenButton
showDeleteButton
/>
<AppointmentForm />
</Scheduler>
</Paper>
);
}
}
My function component code:
import React, { useState } from 'react';
import Paper from '#material-ui/core/Paper';
import { ViewState, EditingState } from '#devexpress/dx-react-scheduler';
import {
Scheduler,
Appointments,
AppointmentForm,
AppointmentTooltip,
WeekView,
ConfirmationDialog,
} from '#devexpress/dx-react-scheduler-material-ui';
const DataSheet = ( { addShift, shifts, deleteShift } ) => {
const [data, setData] = useState(shifts)
const [currentDate, setCurrentDate] = useState('2018-06-27')
const [addedAppointment, setAddedAppointment] = useState({})
const [appointmentChanges, setAppointmentChanges] = useState({})
const [editingAppointment, setEditingAppointment] = useState(undefined)
const changeAddedAppointment = (addedAppointment) => {
setAddedAppointment({ addedAppointment });
}
const changeAppointmentChanges = (appointmentChanges) => {
setAppointmentChanges({ appointmentChanges });
}
const changeEditingAppointment = (editingAppointment) => {
setEditingAppointment({ editingAppointment });
}
const commitChanges = ({ added, changed, deleted }) => {
setData ((????) => {
let { data } = data;
console.log(data); //returns undefined
if (added) {
const startingAddedId = data > 0 ? data[data.length - 1].id + 1 : 0;
data = [...data, { id: startingAddedId, ...added }];
addShift(added);
}
return { data };
});
}
return (
<Paper>
<Scheduler
data={data}
height={660}
>
<ViewState
currentDate={currentDate}
/>
<EditingState
onCommitChanges={commitChanges}
addedAppointment={addedAppointment}
onAddedAppointmentChange={changeAddedAppointment}
appointmentChanges={appointmentChanges}
onAppointmentChangesChange={changeAppointmentChanges}
editingAppointment={editingAppointment}
onEditingAppointmentChange={changeEditingAppointment}
/>
<WeekView
startDayHour={9}
endDayHour={17}
/>
<Appointments />
<AppointmentTooltip
showOpenButton
showDeleteButton
/>
<AppointmentForm />
</Scheduler>
</Paper>
);
}
export default DataSheet
App.js:
import React from 'react';
import backgroundImage from './Resources/BennyBackground.jpeg'
import Header from "./components/Header";
import { useState, useEffect } from "react"
import DataSheet from './components/DataSheet';
const containerStyle= {
width: '100vw',
height: '100vh',
backgroundImage: `url(${backgroundImage})`,
backgroundPosition: 'center',
backgroundSize: 'cover',
backgroundRepeat: 'no-repeat',
}
const App = () => {
const [shifts, setShifts] = useState([])
useEffect(() => {
const getShifts = async () => {
const shiftsFromServer = await fetchShifts()
setShifts(shiftsFromServer)
}
getShifts()
}, [])
const fetchShifts = async () => {
const res = await fetch(`http://localhost:5000/shifts/`)
const data = await res.json()
return data
}
const addShift = async (shift) => {
const startingAddedId = shifts.length > 0 ? shifts[shifts.length - 1].id + 1 : 0;
shift.id = startingAddedId;
const res = await fetch(`http://localhost:5000/shifts/`,{
method: 'POST',
headers: {
'Content-type': 'application/json'
},
body: JSON.stringify(shift)
})
const data = await res.json()
setShifts([...shifts, data])
}
return (
<div className="container"
style={containerStyle} >
<div className='secondary_container'>
<Header />
<DataSheet shifts={shifts} addShift={addShift}/>
</div>
</div>
);
}
export default App;
I know it is a lot of code and a lot to ask and I would highly appreciate help with this.

I believe the issue is that you are using setXxx as you would use this.setState. In class components, you have one function that modifies all the state (this.setState), while in function components you have a setter function for each field.
So change this:
const changeAddedAppointment = (addedAppointment) => {
setAddedAppointment({ addedAppointment });
}
to this:
const changeAddedAppointment = (addedAppointment) => {
setAddedAppointment(addedAppointment);
}
As far as the commitChanges function goes, you can do the data manipulation before using setData. Also I'm not sure that this let { data } = data would work since there is already a data field. You can try this:
const commitChanges = ({ added, changed, deleted }) => {
let newData = [...data.data];
if (added) {
const startingAddedId = newData > 0 ? newData [data.length - 1].id + 1 : 0;
newData = [...newData , { id: startingAddedId, ...added }];
addShift(added);
}
setData(newData);
};

react native: what is the way to get only the `zoneData[index].Zone_ID` in the onPress button?

what is the way to get only the zoneData[index].Zone_ID in the onPress button ?
the below example take some data from table .
in this situation now while i press button so it return everything but i need only the zoneData[index].Zone_ID .
I have tried all kinds of ways but without success and would love to know how the right way.
import React from 'react';
import SQLite from 'react-native-sqlite-storage';
import {View, Button, ScrollView} from 'react-native';
const db = SQLite.openDatabase ({
name: 'Dogmim_DB',
createFromLocation: '~ / Dogmim_DB.db',
});
export default class SQLiteScreen extends React.Component {
constructor () {
super ();
SQLite.DEBUG = true;
}
SelectQuery () {
const promise = new Promise ((resolve, reject) => {
db.transaction ((tx) => {
tx.executeSql (
'SELECT Successor_Zones, Water_Source_Groups FROM tblUserConnectResponseData',
[],
(_, result) => {
for (let i = 0; i <result.rows.length; i ++) {
//// Successor_Zones
const Successor_Zones = result.rows.item (i) ['Successor_Zones'];
const zoneData = JSON.parse (Successor_Zones);
if (zoneData.length> 0) {
for (let index = 0; index <zoneData.length; index ++) {
console.log ('Zone_ID:' + zoneData [index] .Zone_ID);
console.log ('Zone_Name:' + zoneData [index] .Zone_Name);
}
}
//// Water_Source_Groups
const Water_Source_Groups = result.rows.item (i) [
'Water_Source_Groups'
];
const waterData = JSON.parse (Water_Source_Groups);
if (waterData.length> 0) {
for (let index = 0; index <waterData.length; index ++) {
console.log ('Group_Name:' + waterData [index] .Group_Name);
console.log ('Zone_ID:' + waterData [index] .Zone_ID);
}
}
}
resolve ({
isAny: true,
});
},
(_, err) => {
reject (err);
}
);
});
});
}
render () {
return (
<View>
<Button onPress = {this.SelectQuery} title = "Press Me" />
</View>
);
}
}