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React child component state is lost after parent component re-renders

I am using a React hook for parent/child component.
Now I have state in my parent component (companyIcon), which I need to update based on some validation in the child component. I pass validationCallback as a callback function to the child component and update my parent state based on the value I get from the child.
Now the issue is after I update the parent state, the state value in my child component gets reset. What I am doing wrong in the below implementation ?
function ParentComp(props) {
const [companyIcon, setCompanyIcon] = useState({ name: "icon", value: '' });
const validationCallback = useCallback((tabId, hasError) => {
if (hasError) {
setCompanyIcon(prevItem => ({ ...prevItem, value: 'error'}));
// AFTER ABOVE LINE IS EXECUTED, my Child component state "myAddress" is lost i.e. it seems to reset back to empty value.
}
}, []);
const MyChildCmp = (props) => {
const [myAddress, setmyAddress] = useState('');
useEffect(() => {
if (myAddressExceptions.length > 0) {
props.validationCallback('MyInfo', true);
} else {
props.validationCallback('MyInfo', false);
}
}, [myAddressExceptions])
const handlemyAddressChange = (event) => {
//setmyAddress(event.target.value);
//setmyAddressExceptions(event.target.value);
console.log(myAddressExceptions);
}
return (
<>
<div className="row" style={{ display: 'flex', flexDirection: 'row', width: '1000px'}}>
<div style={{ width: '20%'}}>
<FormField
label='Company Address'
required
helperText={mergedErrorMessages(myAddressExceptions)}
validationState={
myAddressExceptions[0] ? myAddressExceptions[0].type : ''
}
>
<Input id='myAddress'
value={myAddress}
//onChange={handlemyAddressChange}
onChange={({ target: { value } }) => {
validateInputValue(value);
}}
onBlur={handleBlur}
inputProps={{maxLength: 9}} />
</FormField>
</div>
</div>
</>
);
}
return (
<div className="mainBlock">
Parent : {companyIcon}
{displayMyChild && <MyChildCmp validationCallback={validationCallback}/>}
</div>
)
}
export default withRouter(ParentComp);

Here are some reasons why you can lose state in child (there could be more, but these apply to you most):
{displayMyChild && <MyChildCmp validationCallback={validationCallback}/>}
Here if at one point displayMyChild is truthy, then made falsy, this means the component MyChildCmp will get unmounted, hence all its state will be gone.
But now, even if you didn't have that condition and rendered the MyChildCmp always you would still run into similar problem, this is because you defined MyChildCmp inside another component. When you do that, on each render of the parent component, the function MyChildCmp is recreated, and the reconciliation algorithm of react thinks you rendered a different component type on next render, so it will destroy the component instance. Move definition of that component outside the parent component.

React.useCallback not updating its implementation when state is updated

I am creating a todo application using React hooks. The way I am doing this is by creating a context for a single todo and a context for all todos. The NewTodoContext would be parent to the new todo react components and will take up responsibilities like having an internal state, providing callback to update that state, reset that state and update AllTodosContext once user confirms todo formation.
The NewTodoProvider would look like
function NewTodoProvider({ children }){
const [todo, setTodo] = React.useState(DEFAULT_EMPTY_TODO_STATE);
const [ addTodo ] = React.useContext(AllTodosContext);
const updateTodo = React.useCallback((todoFragment) => {
// setTodo({...todo, ...todoFragment})
}, [todo]);
const confirmTodo = React.useCallback(() => { addTodo(todo) }, [todo]);
return (
<NewTodoContext.Provider value={{ todo, updateTodo, confirmTodo }}>
{ children }
</NewTodoContext.Provider>
)
}
The AllTodosProvider would look like
function AllTodosProvider({ children }){
const [todos, setTodos] = React.useState();
const addTodo = React.useCallback((todo) => {
setTodos([...todos, todo]);
},[todos]);
return (
<AllTodosContext.Provider value={{ todos, addTodo }}>
{ children }
</AllTodosContext.Provider>
)
}
and the React tree would be like
<AllTodosProvider>
<DifferentComponents />
<NewTodoButton />
<DifferentComponents />
</AllTodosProvider>
// NewTodoButton would open up into
<NewTodoProvider>
<SomeFormComponent />
</NewTodoProvider>
Now coming to the issue I am facing. As you can see, the confirmTodo is wrapped in useCallback with todo as a dependency so that it has the latest state of NewTodoProvider, but that doesn't seem to be the case. When confirmTodo is called, it seems to pick up the default state, hinting that its implementation remained unchanges inspite of state changes. What am I missing here?

Bug with React: component not rendering until page is refreshed

I have this carousel component that I'm calling from a page but it's not showing until I refresh the page. If I have the Box component and switch to the Carousel component it doesn't work until I refresh the page but if I render the Carousel component first, render Box then go back to Carousel it works. Is this a bug with ReactDOM or what?
My carousel component:
const Carousel = () => {
const { carousel, setCarousel } = useContext(AppContext);
useEffect(() => {
setCarousel(true);
return () => {
setCarousel(false);
};
}, [carousel]);
const items = ["image1.svg", "image2.svg", "image1.svg", "image2.svg"];
const responsive = {
0: { items: 1 },
1024: { items: 2 },
};
return (
<div
className={`container flex`}
style={{
marginTop: "40px",
}}>
<AliceCarousel
disableDotsControls
disableButtonsControls
autoHeight={true}
autoWidth={true}
responsive={responsive}
animationType='slide'>
{items.map((i, index) => (
<img src={i} key={index} alt='' srcSet='' className={Styles.slider} />
))}
</AliceCarousel>
</div>
);
};
And I'm switching/calling it on another component like this:
const { carousel, modalIsOpen, openModal, closeModal } = useContext(
AppContext
);
return (
<div className={carousel ? Styles.layout : ""}>
<div>
<Box />
</div>
</div>
)
I need to make the component re-render when it's called or something so that it works properly, even when I call the AliceCarousel component on my page directly I still have this issue.
Is this something to do with React or the component itself? Thanks

Your useEffect logic leads to infinity loop as after changing the state to true, by having the state in dep array [carousel], you changing it back to false from the cleanup function.
// Useless useEffect, always false.
useEffect(() => {
setCarousel(true);
return () => {
setCarousel(false);
};
}, [carousel]);
See When does the useEffect's callback's return statement execute?

Send selected options from react dual listbox with post request

I'm trying to implement in my react app, two react double listbox in my component. At the moment the listboxes are filled automatically after a get request when component mounts. I need some help on how to get the selected options in each double listbox and send them to the server as json data.
I need two arrays from these lists.
This is my dual listbox classes:
import React from 'react';
import DualListBox from 'react-dual-listbox';
import 'react-dual-listbox/lib/react-dual-listbox.css';
import 'font-awesome/css/font-awesome.min.css';
export class FirstList extends React.Component {
state = {
selected: [],
};
onChange = (selected) => {
this.setState({ selected });
};
render() {
const { selected } = this.state;
return (
<DualListBox
canFilter
filterPlaceholder={this.props.placeholder || 'Search From List 1...'}
options={this.props.options}
selected={selected}
onChange={this.onChange}
/>
);
}
}
export class SecondList extends React.Component {
state = {
selected: [],
};
onChange = (selected) => {
this.setState({ selected });
};
render() {
const { selected } = this.state;
return (
<DualListBox
canFilter
filterPlaceholder={this.props.placeholder || 'Search From List 2...'}
options={this.props.options}
selected={selected}
onChange={this.onChange}
/>
);
}
}
In my component I started importing this:
import React, { useState, useEffect } from 'react'
import LoadingSpinner from '../shared/ui-elements/LoadingSpinner';
import ErrorModal from '../shared/ui-elements/ErrorModal';
import { FirstList, SecondList } from '../shared/formElements/DualListBox';
import { useHttpClient } from '../shared/hooks/http-hook';
const MyComponent = () => {
const { isLoading, error, sendRequest, clearError } = useHttpClient();
const [loadedRecords, setLoadedRecords] = useState();
useEffect(() => {
const fetchRecords = async () => {
try {
const responseData = await sendRequest(
process.env.REACT_APP_BACKEND_URL + '/components/get'
);
setLoadedRecords(responseData)
} catch (err) { }
};
fetchRecords();
}, [sendRequest]);
...
...
return (
<React.Fragment>
<ErrorModal error={error} onClear={clearError} />
<form>
<div className="container">
<div className="row">
<div className="col-md-6">
<fieldset name="SerialField" className="border p-4">
<legend className="scheduler-border"></legend>
<div className="container">
<p>SERIALS</p>
{loadedRecords ? (
<FirstList id='Serials' options={loadedRecords.firstRecordsList} />
) : (
<div>
<label>List is loading, please wait...</label>
{isLoading && <LoadingSpinner />}
</div>
)}
</div>
</fieldset>
</div>
<div className="col-md-6">
<fieldset name="SystemsField" className="border p-4">
<legend className="scheduler-border"></legend>
<div className="container">
<p>SYSTEMS</p>
{loadedRecords ? (
<SecondList options={loadedRecords.secondRecordsList} />
) : (
<div>
<label>List is loading, please wait...</label>
{isLoading && <LoadingSpinner />}
</div>
)}
</div>
</fieldset>
</div>
...
...
If anyone could guide me it'll be much appreciated.
Thanks in advance!

FirstList and SecondList are using internal state to show the selected values. Since a parent component should do the server request, it needs access to this data. This can be achieved by a variety of options:
Let the parent component (MyComponent) handle the state completely. FirstList and SecondList would need two props: One for the currently selected values and another for the onChange event. MyComponent needs to manage that state. For example:
const MyComponent = () => {
const [firstListSelected, setFirstListSelected] = useState();
const [secondListSelected, setSecondListSelected] = useState();
...
return (
...
<FirstList options={...} selected={firstListSelected} onChange={setFirstListSelected} />
...
<SecondList options={...} selected={secondListSelected} onChange={setSecondListSelected} />
...
)
Provide only the onChange event and keep track of it. This would be very similar to the first approach, but the lists would keep managing their state internally and only notify the parent when a change happens through onChange. I usually don't use that approach since it feels like I'm managing the state of something twice and I also need to know the initial state of the two *List components to make sure I am always synchronized properly.
Use a ref, call an imperative handle when needed from the parent. I wouldn't recommend this as it's usually not done like this and it's getting harder to share the state somewhere else than inside of the then heavily coupled components.
Use an external, shared state like Redux or Unstated. With global state, the current state can be reused anywhere in the Application and it might even exist when the user clicks away / unmounts MyComponent. Additional server requests wouldn't be necessary if the user navigated away and came back to the component. Anyways, using an external global state needs additional setup and usually feels "too much" and like a very high-end solution that is probably not necessary in this specific case.
By using option 1 or 2 there is a notification for the parent component when something changed. On every change a server request could be sent (might even be debounced). Or there could be a Submit button which has a callback that sends the saved state to the server.

Material-ui dialog flickering when using redux for open state

I am trying to move the open state for material-ui dialog to redux to prevent it from closing when a rerender occurs, but i having trouble with the dialog when a rerender occurs. Although the state is saved in redux and the dialog does stay open whenever a rerender occurs the open state stays open but the dialog does show the open animation (fading in) which is kinda annoying.
Students.js (parent component of the modal)
const Students = ({
app: { studentsPage: { savedAddDialogOpen }},
setStudentsPageAddDialogOpen}) => {
// Create the local states
const [dialogOpen, setDialogOpen] = React.useState(savedAddDialogOpen);
const dialogOpenRef = React.useRef(savedAddDialogOpen);
// Change redux dialog open
const setReduxDialogState = () => {
setStudentsPageAddDialogOpen(dialogOpenRef.current, savedAddDialogOpen);
};
// Open add student dialog
const dialogClickOpen = () => {
setDialogOpen(true);
dialogOpenRef.current = true;
setTimeout(() => setReduxDialogState(), 300);
};
// Close add student dialog
const dialogClose = () => {
setDialogOpen(false);
dialogOpenRef.current = false;
setTimeout(() => setReduxDialogState(), 300);
};
return (
<Container>
{/* Add student modal */}
<AddStudentModal dialogOpen={dialogOpen} dialogClose={dialogClose} />
</Container>
)
}
// Set the state for this component to the global state
const mapStateToProps = (state) => ({
app: state.app,
});
AddStudentModal.js
const AddStudentModal = ({
dialogOpen, dialogClose
}) => {
return (
<Dialog
open={dialogOpen}
>
{/* Lots of stuff*/}
<DialogActions>
<Button onClick={dialogClose}>
Close dialog
</Button>
</DialogActions>
</Dialog>
)
};
I hope this should be sufficient. I tried checking if the open state is actually correct when a rerender occurs and it is correct every time but it looks like the dialog is closed at a rerender no matter what the open state is and only a few ms later actually notices that it should be opened.
Any help would be really appreciated
Edit 1: Found out it has nothing to do with the open state coming from redux, if i use open={true} it still flashes, so probably a problem with material-ui itself?
Edit 2: PrivateRoute.js
const PrivateRoute = ({
auth: { isAuthenticated, loadingAuth },
user: { loggedInUser },
component: Component,
roles,
path,
setLastPrivatePath,
...rest
}) => {
useEffect(() => {
if (path !== '/dashboard' && path !== '/profile') {
setLastPrivatePath(path);
}
// Prevent any useless errors with net line:
// eslint-disable-next-line
}, [path]);
// If we are loading the user show the preloader
if (loadingAuth) {
return <Preloader />;
}
// Return the component (depending on authentication)
return (
<Route
{...rest}
render={props =>
!isAuthenticated ? (
<Redirect to="/login" />
) : (loggedInUser && roles.some(r => loggedInUser.roles.includes(r))) ||
roles.includes('any') ? (
<Component {...props} />
) : (
<NotAuthorized />
)
}
/>
);
};
// Set the state for this component to the global state
const mapStateToProps = state => ({
auth: state.auth,
user: state.user
});

I found the problem thanks to #RyanCogswell!
For anyone having the same problem here is the cause for me and the fix:
I was passing components into the Route component like this:
<PrivateRoute
exact
path={'/dashboard/students'}
component={(props) => (
<Students {...props} selectedIndex={selectedIndexSecondary} />
)}
roles={['admin']}
/>
By doing it this way i could pass props through my privateRoute function but this would also happen if you send the component this way in a normal Route component
Solution for me is just moving selectedIndexSecondary to redux and sending the component the normal way it prevented the re-mounting.
So just doing it like this will prevent this from happening.
<PrivateRoute
exact
path={'/dashboard/students'}
component={Students}
roles={['admin']}
/>
Also this will solve the localstates in your components from resseting to the default value. So for me it fixed two problems!