How to select list item using redux?

How to select list item using redux? - javascript

I'm trying to select a song from the playlist, but selection doesn't work as it should, because, when I click for the first time it returns "null" when I click on the second time it selects an item, but for some reason, when I keep clicking on different items I always get a previous item value, and I don't know why.
//Here is my action from redux:
import {FETCH_PLAYLIST_SUCCESS, FETCH_PLAYLIST_FAILURE, FETCH_PLAYLIST_REQUEST, SELECT_TRACK} from './types'
import {PREV, PLAY, PAUSE, NEXT, TOGGLE_TRACK} from './types';
import axios from "axios/index";
export const getPlayList = id => {
return function (dispatch) {
dispatch({type: FETCH_PLAYLIST_REQUEST});
axios.get('https://cors-anywhere.herokuapp.com/https://api.deezer.com/search/track?q=red+hot+chili+peppers').then(response => {
dispatch({
type: FETCH_PLAYLIST_SUCCESS,
payload: {
playlist: response.data.data,
currentTrack: response.data.data[0]
}
});
}).catch(err => {
dispatch({
type: FETCH_PLAYLIST_FAILURE,
payload: err,
});
})
}
};
//func which takes index of list item
export const selectTrack = (i) =>{
return function (dispatch) {
dispatch({
type: SELECT_TRACK,
payload: i
});
}
}
//reducer
case SELECT_TRACK:
return {
...state,
selectedTrack: state.playList[action.payload],
};
//click handler in container component
handleClick = (index) => {
this.props.selectTrack(index);
console.log(this.props.playlist.selectedTrack);
console.log(index);
};
//how I'm using it in playlist component
<Playlist handleClick={this.handleClick} tracks={this.props.playlist.playList}/>
//Playlist component
function PlayList(props) {
const {i,handleClick,currentSongIndex,tracks,isSelected,} = props;
return (
<div className="playlist-container">
<div className="playlist">
<ul>
{
tracks.map((track, index) => (
<Track
isSelected={isSelected}
index={index}
key={track.id}
id={track.id}
title_short={track.title}
duration={track.duration}
clickHandler={ () => handleClick(index)}
/>
))
}
</ul>
</div>
</div>
);
}
See how it works on screenshots

Upon item click, you are dispatching the action in the click handler of the container. The props in the handler at the time of console.log is still the old props. The new props will arrive only once redux updates state and component updates its props via the react lifecycle methods.
I am guessing you have not set any intial state in the reducer which might be the reason why the first value is coming as null.
Try adding the same statement : console.log(this.props.playlist.selectedTrack) in the render method. You should see the updated prop

#Easwar is correct (above) that your debugging logic is problematic.
With respect to the core problem, I don't see where some of your important props are passed in. You have:
const {i,handleClick,currentSongIndex,tracks,isSelected,} = props;
In your PlayList component, but you're invoking it like this:
<Playlist handleClick={this.handleClick} tracks={this.props.playlist.playList}/>
Where are currentSongIndex and isSelected passed in? Your trouble is likely there. It looks like they'll evaluate to null in <Playlist>'s render method.

Related

Getting a warning while using firebase login system [duplicate]

I am getting this warning in react:
index.js:1 Warning: Cannot update a component (`ConnectFunction`)
while rendering a different component (`Register`). To locate the
bad setState() call inside `Register`
I went to the locations indicated in the stack trace and removed all setstates but the warning still persists. Is it possible this could occur from redux dispatch?
my code:
register.js
class Register extends Component {
render() {
if( this.props.registerStatus === SUCCESS) {
// Reset register status to allow return to register page
this.props.dispatch( resetRegisterStatus()) # THIS IS THE LINE THAT CAUSES THE ERROR ACCORDING TO THE STACK TRACE
return <Redirect push to = {HOME}/>
}
return (
<div style = {{paddingTop: "180px", background: 'radial-gradient(circle, rgba(106,103,103,1) 0%, rgba(36,36,36,1) 100%)', height: "100vh"}}>
<RegistrationForm/>
</div>
);
}
}
function mapStateToProps( state ) {
return {
registerStatus: state.userReducer.registerStatus
}
}
export default connect ( mapStateToProps ) ( Register );
function which triggers the warning in my registerForm component called by register.js
handleSubmit = async () => {
if( this.isValidForm() ) {
const details = {
"username": this.state.username,
"password": this.state.password,
"email": this.state.email,
"clearance": this.state.clearance
}
await this.props.dispatch( register(details) )
if( this.props.registerStatus !== SUCCESS && this.mounted ) {
this.setState( {errorMsg: this.props.registerError})
this.handleShowError()
}
}
else {
if( this.mounted ) {
this.setState( {errorMsg: "Error - registration credentials are invalid!"} )
this.handleShowError()
}
}
}
Stacktrace:

This warning was introduced since React V16.3.0.
If you are using functional components you could wrap the setState call into useEffect.
Code that does not work:
const HomePage = (props) => {
props.setAuthenticated(true);
const handleChange = (e) => {
props.setSearchTerm(e.target.value.toLowerCase());
};
return (
<div key={props.restInfo.storeId} className="container-fluid">
<ProductList searchResults={props.searchResults} />
</div>
);
};
Now you can change it to:
const HomePage = (props) => {
// trigger on component mount
useEffect(() => {
props.setAuthenticated(true);
}, []);
const handleChange = (e) => {
props.setSearchTerm(e.target.value.toLowerCase());
};
return (
<div key={props.restInfo.storeId} className="container-fluid">
<ProductList searchResults={props.searchResults} />
</div>
);
};

I just had this issue and it took me a bit of digging around before I realised what I'd done wrong – I just wasn't paying attention to how I was writing my functional component.
I was doing this:
const LiveMatches = (props: LiveMatchesProps) => {
const {
dateMatches,
draftingConfig,
sportId,
getDateMatches,
} = props;
if (!dateMatches) {
const date = new Date();
getDateMatches({ sportId, date });
};
return (<div>{component stuff here..}</div>);
};
I had just forgotten to use useEffect before dispatching my redux call of getDateMatches()
So it should have been:
const LiveMatches = (props: LiveMatchesProps) => {
const {
dateMatches,
draftingConfig,
sportId,
getDateMatches,
} = props;
useEffect(() => {
if (!dateMatches) {
const date = new Date();
getDateMatches({ sportId, date });
}
}, [dateMatches, getDateMatches, sportId]);
return (<div>{component stuff here..}</div>);
};

please read the error message thoroughly, mine was pointing to SignIn Component that had a bad setState. which when i examined, I had an onpress that was not an Arrow function.
it was like this:
onPress={navigation.navigate("Home", { screen: "HomeScreen" })}
I changed it to this:
onPress={() => navigation.navigate("Home", { screen: "HomeScreen" }) }
My error message was:
Warning: Cannot update a component
(ForwardRef(BaseNavigationContainer)) while rendering a different
component (SignIn). To locate the bad setState() call inside
SignIn, follow the stack trace as described in
https://reactjs.org/link/setstate-in-render
in SignIn (at SignInScreen.tsx:20)

I fixed this issue by removing the dispatch from the register components render method to the componentwillunmount method. This is because I wanted this logic to occur right before redirecting to the login page. In general it's best practice to put all your logic outside the render method so my code was just poorly written before. Hope this helps anyone else in future :)
My refactored register component:
class Register extends Component {
componentWillUnmount() {
// Reset register status to allow return to register page
if ( this.props.registerStatus !== "" ) this.props.dispatch( resetRegisterStatus() )
}
render() {
if( this.props.registerStatus === SUCCESS ) {
return <Redirect push to = {LOGIN}/>
}
return (
<div style = {{paddingTop: "180px", background: 'radial-gradient(circle, rgba(106,103,103,1) 0%, rgba(36,36,36,1) 100%)', height: "100vh"}}>
<RegistrationForm/>
</div>
);
}
}

I think that this is important.
It's from this post that #Red-Baron pointed out:
#machineghost : I think you're misunderstanding what the message is warning about.
There's nothing wrong with passing callbacks to children that update state in parents. That's always been fine.
The problem is when one component queues an update in another component, while the first component is rendering.
In other words, don't do this:
function SomeChildComponent(props) {
props.updateSomething();
return <div />
}
But this is fine:
function SomeChildComponent(props) {
// or make a callback click handler and call it in there
return <button onClick={props.updateSomething}>Click Me</button>
}
And, as Dan has pointed out various times, queuing an update in the same component while rendering is fine too:
function SomeChildComponent(props) {
const [number, setNumber] = useState(0);
if(props.someValue > 10 && number < 5) {
// queue an update while rendering, equivalent to getDerivedStateFromProps
setNumber(42);
}
return <div>{number}</div>
}

If useEffect cannot be used in your case or if the error is NOT because of Redux
I used setTimeout to redirect one of the two useState variables to the callback queue.
I have one parent and one child component with useState variable in each of them. The solution is to wrap useState variable using setTimeout:
setTimeout(() => SetFilterData(data), 0);
Example below
Parent Component
import ExpenseFilter from '../ExpensesFilter'
function ExpensesView(props) {
const [filterData, SetFilterData] = useState('')
const GetFilterData = (data) => {
// SetFilterData(data);
//*****WRAP useState VARIABLE INSIDE setTimeout WITH 0 TIME AS BELOW.*****
setTimeout(() => SetFilterData(data), 0);
}
const filteredArray = props.expense.filter(expenseFiltered =>
expenseFiltered.dateSpent.getFullYear().toString() === filterData);
return (
<Window>
<div>
<ExpenseFilter FilterYear = {GetFilterData}></ExpenseFilter>
Child Component
const ExpensesFilter = (props) => {
const [filterYear, SetFilterYear] = useState('2022')
const FilterYearListener = (event) => {
event.preventDefault()
SetFilterYear(event.target.value)
}
props.FilterYear(filterYear)
return (

Using React and Material UI (MUI)
I changed my code from:
<IconButton onClick={setOpenDeleteDialog(false)}>
<Close />
</IconButton>
To:
<IconButton onClick={() => setOpenDeleteDialog(false)}>
<Close />
</IconButton>
Simple fix

If you use React Navigation and you are using the setParams or setOptions you must put these inside method componentDidMount() of class components or in useEffects() hook of functional components.

Minimal reproducing example
I was a bit confused as to what exactly triggers the problem, having a minimal immediately runnable example helped me grasp it a little better:
index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<script src="https://unpkg.com/react#17/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom#17/umd/react-dom.development.js"></script>
<script src="https://unpkg.com/#babel/standalone#7.14.7/babel.min.js"></script>
</head>
<body>
<div id="root"></div>
<script type="text/babel">
function NotMain(props) {
props.setN(1)
return <div>NotMain</div>
}
function Main(props) {
const [n, setN] = React.useState(0)
return <>
<NotMain setN={setN} />
<div>Main {n}</div>
</>
}
ReactDOM.render(
<Main/>,
document.getElementById('root')
);
</script>
</body>
</html>
fails with error:
react-dom.development.js:61 Warning: Cannot update a component (`Main`) while rendering a different component (`NotMain`). To locate the bad setState() call inside `NotMain`, follow the stack trace as described in https://reactjs.org/link/setstate-in-render
followed by a stack trace:
at NotMain (<anonymous>:16:9)
at Main (<anonymous>:21:31)
Presumably 16:9 would be the exact line where props.setN(1) is being called from, but the line numbers are a bit messed up because of the Babel JSX translation.
The solution like many other answers said is to do instead:
function NotMain(props) {
React.useEffect(() => { props.setN(1) }, [])
return <div>NotMain</div>
}
Intuitively, I think that the general idea of why this error happens is that:
You are not supposed to updat state from render methods, otherwise it could lead to different results depending on internal the ordering of how React renders things.
and when using functional components, the way to do that is to use hooks. In our case, useEffect will run after rendering is done, so we are fine doing that from there.
When using classes this becomes slightly more clear and had been asked for example at:
Calling setState in render is not avoidable
Calling setState() in React from render method
When using functional components however, things are conceptually a bit more mixed, as the component function is both the render, and the code that sets up the callbacks.

I was facing same issue, The fix worked for me was if u are doing
setParams/setOptions
outside of useEffect then this issue is occurring. So try to do such things inside useEffect. It'll work like charm

TL;DR;
For my case, what I did to fix the warning was to change from useState to useRef
react_devtools_backend.js:2574 Warning: Cannot update a component (`Index`) while rendering a different component (`Router.Consumer`). To locate the bad setState() call inside `Router.Consumer`, follow the stack trace as described in https://reactjs.org/link/setstate-in-render
at Route (http://localhost:3000/main.bundle.js:126692:29)
at Index (http://localhost:3000/main.bundle.js:144246:25)
at Switch (http://localhost:3000/main.bundle.js:126894:29)
at Suspense
at App
at AuthProvider (http://localhost:3000/main.bundle.js:144525:23)
at ErrorBoundary (http://localhost:3000/main.bundle.js:21030:87)
at Router (http://localhost:3000/main.bundle.js:126327:30)
at BrowserRouter (http://localhost:3000/main.bundle.js:125948:35)
at QueryClientProvider (http://localhost:3000/main.bundle.js:124450:21)
The full code for the context of what I did (changed from the lines with // OLD: to the line above them). However this doesn't matter, just try changing from useState to useRef!!
import { HOME_PATH, LOGIN_PATH } from '#/constants';
import { NotFoundComponent } from '#/routes';
import React from 'react';
import { Redirect, Route, RouteProps } from 'react-router-dom';
import { useAccess } from '#/access';
import { useAuthContext } from '#/contexts/AuthContext';
import { AccessLevel } from '#/models';
type Props = RouteProps & {
component: Exclude<RouteProps['component'], undefined>;
requireAccess: AccessLevel | undefined;
};
export const Index: React.FC<Props> = (props) => {
const { component: Component, requireAccess, ...rest } = props;
const { isLoading, isAuth } = useAuthContext();
const access = useAccess();
const mounted = React.useRef(false);
// OLD: const [mounted, setMounted] = React.useState(false);
return (
<Route
{...rest}
render={(props) => {
// If in indentifying authentication state as the page initially loads, render a blank page
if (!mounted.current && isLoading) return null;
// OLD: if (!mounted && isLoading) return null;
// 1. Check Authentication is one step
if (!isAuth && window.location.pathname !== LOGIN_PATH)
return <Redirect to={LOGIN_PATH} />;
if (isAuth && window.location.pathname === LOGIN_PATH)
return <Redirect to={HOME_PATH} />;
// 2. Authorization is another
if (requireAccess && !access[requireAccess])
return <NotFoundComponent />;
mounted.current = true;
// OLD: setMounted(true);
return <Component {...props} />;
}}
/>
);
};
export default Index;

My example.
Code with that error:
<Form
initialValues={{ ...kgFormValues, dataflow: dataflows.length > 0 ? dataflows[0].df_tpl_key : "" }}
onSubmit={() => {}}
render={({values, dirtyFields }: any) => {
const kgFormValuesUpdated = {
proj_key: projectKey,
name: values.name,
description: values.description,
public: values.public,
dataflow: values.dataflow,
flavours: flavoursSelected,
skipOCR: values.skipOCR
};
if (!_.isEqual(kgFormValues, kgFormValuesUpdated)) {
setNewKgFormValues(kgFormValuesUpdated);
}
Working Code:
<Form
initialValues={{ ...kgFormValues, dataflow: dataflows.length > 0 ? dataflows[0].df_tpl_key : "" }}
onSubmit={() => {}}
render={({ values, dirtyFields }: any) => {
useEffect(() => {
const kgFormValuesUpdated = {
proj_key: projectKey,
name: values.name,
description: values.description,
public: values.public,
dataflow: values.dataflow,
flavours: flavoursSelected,
skipOCR: values.skipOCR
};
if (!_.isEqual(kgFormValues, kgFormValuesUpdated)) {
setNewKgFormValues(kgFormValuesUpdated);
}
}, [values]);
return (

I had the same problem. I was setting some state that was storing a function like so:
// my state definition
const [onConfirm, setOnConfirm] = useState<() => void>();
// then I used this piece of code to update the state
function show(onConfirm: () => void) {
setOnConfirm(onConfirm);
}
The problem was from setOnConfirm. In React, setState can take the new value OR a function that returns the new value. In this case React wanted to get the new state from calling onConfirm which is not correct.
changing to this resolved my issue:
setOnConfirm(() => onConfirm);

I was able to solve this after coming across a similar question in GitHub which led me to this comment showing how to pinpoint the exact line within your file causing the error. I wasn't aware that the stack trace was there. Hopefully this helps someone!
See below for my fix. I simply converted the function to use callback.
Old code
function TopMenuItems() {
const dispatch = useDispatch();
function mountProjectListToReduxStore(projects) {
const projectDropdown = projects.map((project) => ({
id: project.id,
name: project.name,
organizationId: project.organizationId,
createdOn: project.createdOn,
lastModifiedOn: project.lastModifiedOn,
isComplete: project.isComplete,
}));
projectDropdown.sort((a, b) => a.name.localeCompare(b.name));
dispatch(loadProjectsList(projectDropdown));
dispatch(setCurrentOrganizationId(projectDropdown[0].organizationId));
}
};
New code
function TopMenuItems() {
const dispatch = useDispatch();
const mountProjectListToReduxStore = useCallback((projects) => {
const projectDropdown = projects.map((project) => ({
id: project.id,
name: project.name,
organizationId: project.organizationId,
createdOn: project.createdOn,
lastModifiedOn: project.lastModifiedOn,
isComplete: project.isComplete,
}));
projectDropdown.sort((a, b) => a.name.localeCompare(b.name));
dispatch(loadProjectsList(projectDropdown));
dispatch(setCurrentOrganizationId(projectDropdown[0].organizationId));
}, [dispatch]);
};

My case was using setState callback, instead of setState + useEffect
BAD ❌
const closePopover = useCallback(
() =>
setOpen((prevOpen) => {
prevOpen && onOpenChange(false);
return false;
}),
[onOpenChange]
);
GOOD ✅
const closePopover = useCallback(() => setOpen(false), []);
useEffect(() => onOpenChange(isOpen), [isOpen, onOpenChange]);

I got this when I was foolishly invoking a function that called dispatch instead of passing a reference to it for onClick on a button.
const quantityChangeHandler = (direction) => {
dispatch(cartActions.changeItemQuantity({title, quantityChange: direction}));
}
...
<button onClick={() => quantityChangeHandler(-1)}>-</button>
<button onClick={() => quantityChangeHandler(1)}>+</button>
Initially, I was directly calling without the fat arrow wrapper.

Cannot update a component while rendering a different component warning
I have the same problem but when I dispatch an action inside a component rendered. You should dispatch the action inside useEffect hook to fix that problem
//dispatch action to inform user that 'Marked days already have hours!'
React.useEffect(() => {
if (btn_class == 'redButton') {
dispatch({ type: ActionType.ADD_NOTIFICATION, payload: 'Marked days already have hours!' });
} else {
dispatch({ type: ActionType.ADD_NOTIFICATION, payload: '' });
}
}, [btn_class, dispatch]);
also use union type for btn-class variable
*`
type ButtonState = 'btnAddDay' | 'redButton' | 'btnAddDayBlue' | 'btnAddDayGreen';
`*

Using some of the answers above, i got rid of the error with the following:
from
if (value === "newest") {
dispatch(sortArticlesNewest());
} else {
dispatch(sortArticlesOldest());
}
this code was on my component top-level
to
const SelectSorting = () => {
const dispatch = useAppDispatch();
const {value, onChange} = useSelect();
useEffect(() => {
if (value === "newest") {
dispatch(sortArticlesNewest());
} else {
dispatch(sortArticlesOldest());
}
}, [dispatch, value]);

Reactj.s: Item deleted only after refresh | Delete Method

I'm trying to send a delete request to delete an item from an API.
The API request is fine when clicking on the button. But Item get's deleted only after refreshing the browser!
I'm not too sure if I should add any parameter to SetHamsterDeleted for it to work?
This is what my code looks like.
import React, {useState} from "react";
const Hamster = (props) => {
const [hamsterDeleted, setHamsterDeleted] = useState("")
async function deleteHamster(id) {
const response = await fetch(`/hamsters/${id}`, { method: "DELETE" });
setHamsterDeleted()
}
return (
<div>
<p className={props.hamster ? "" : "hide"}>
{hamsterDeleted}
</p>
<button onClick={() => deleteHamster(props.hamster.id)}>Delete</button>
<h2>{props.hamster.name}</h2>
<p>Ålder:{props.hamster.age}</p>
<p>Favorit mat:{props.hamster.favFood}</p>
<p>Matcher:{props.hamster.games}</p>
<img src={'./img/' + props.hamster.imgName} alt="hamster"/>
</div>
)
};
export default Hamster;
<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>

Imagine you have a parent component (say HamstersList) that returns/renders list of these Hamster components - it would be preferable to declare that deleteHamster method in it, so it could either: a) pass some prop like hidden into every Hamster or b) refetch list of all Hamsters from the API after one got "deleted" c) remove "deleted" hamster from an array that was stored locally in that parent List component.
But since you are trying to archive this inside of Hamster itself, few changes might help you:
change state line to const [hamsterDeleted, setHamsterDeleted] = useState(false)
call setHamsterDeleted(true) inside of deleteHamster method after awaited fetch.
a small tweak of "conditional rendering" inside of return, to actually render nothing when current Hamster has hamsterDeleted set to true:
return hamsterDeleted ? null : (<div>*all your hamster's content here*</div>)

What do you want to do in the case the hamster is deleted? If you don't want to return anything, you can just return null.
I'm not too sure if I should add any parameter to SetHamsterDeleted for it to work?
Yes, I'd make this a boolean instead. Here's an example:
import React, { useState } from "react";
const Hamster = (props) => {
const [hamsterDeleted, setHamsterDeleted] = useState(false);
async function deleteHamster(id) {
const response = await fetch(`/hamsters/${id}`, { method: "DELETE" });
setHamsterDeleted(true);
}
if (hamsterDeleted) return null;
return (
<div>
<p className={props.hamster ? "" : "hide"}>
{hamsterDeleted}
</p>
<button onClick={() => deleteHamster(props.hamster.id)}>Delete</button>
<h2>{props.hamster.name}</h2>
<p>Ålder:{props.hamster.age}</p>
<p>Favorit mat:{props.hamster.favFood}</p>
<p>Matcher:{props.hamster.games}</p>
<img src={'./img/' + props.hamster.imgName} alt="hamster"/>
</div>
);
};
HOWEVER! Having each individual hamster keep track of its deleted state doesn't sound right (of course I don't know all your requirements but it seems odd). I'm guessing that you've got a parent component which is fetching all the hamsters - that would be a better place to keep track of what has been deleted, and what hasn't. That way, if the hamster is deleted, you could just not render that hamster. Something more like this:
const Hamsters = () => {
const [hamsers, setHamsters] = useState([]);
// Load the hamsters when the component loads
useEffect(() => {
const loadHamsters = async () => {
const { data } = await fetch(`/hamsters`, { method: "GET" });
setHamsters(data);
}
loadHamsters();
}, []);
// Shared handler to delete a hamster
const handleDelete = async (id) => {
await fetch(`/hamsters/${id}`, { method: "DELETE" });
setHamsters(prev => prev.filter(h => h.id !== id));
}
return (
<>
{hamsters.map(hamster => (
<Hamster
key={hamster.id}
hamster={hamster}
onDelete={handleDelete}
/>
))}
</>
);
}
Now you can just make the Hamster component a presentational component that only cares about rendering a hamster, eg:
const Hamster = ({ hamster, onDelete }) => {
const handleDelete = () => onDelete(hamster.id);
return (
<div>
<button onClick={handleDelete}>Delete</button>
<h2>{hamster.name}</h2>
<p>Ålder:{hamster.age}</p>
<p>Favorit mat:{hamster.favFood}</p>
<p>Matcher:{hamster.games}</p>
<img src={'./img/' + hamster.imgName} alt="hamster"/>
</div>
);
};

How to delegate responsibilities to each component correctly in React?

I have a hook, which basically renders a Loading Indicator at the right side of my Stack Header.
Here is how it looks like:
export default function useHeaderRightLoadingIndicator(loading = false) {
const navigation = useNavigation();
const renderLoading = useCallback(() => {
if (!loading) return null;
return (
<Loading
size={20}
style={styles.loadingIndicator}
/>
);
}, [loading]);
useEffect(() => {
navigation.setOptions({
headerRight: renderLoading,
});
}, [navigation, renderLoading]);
}
Now, I want to use it during a delete operation. Basically, I have a screen with a lot of erasable items rendered in a FlatList.
The screen contains the stateful array of data... and pass it to the FlatList component.
In order to avoid repeating my self each time I wanna delete the same item (but in a different screen), I have decided to move the responsibility of the deletion to the item itself (I mean, to the FlatList's item). For this, I have been forced to use a context in order to update the graphical interface without having to pass the "setState" node by node.
So... I have the following:
function MyScreen() {
const statefulData = useData(); // consuming context...
return <CustomFlatList data={statefulData} />
}
...
function ErasableItem({ id }) {
const { isLoading, error, deleteItem } = useDeleteItem(id);
return <Text onPress={deleteItem}>Delete!</Text>;
}
Inside the logic of useDeleteItem, I just make an api call and update my context in order to update the UI (delete the item from the list).
This has sense to me... I don't have a super screen which does everything, instead, each node does its own stuff.
But... what if I wanna use the useHeaderRightLoadingIndicator() I described at the beginning? As I have delegated the deletion responsibility to an unmountable component, I will not be able to stop loading it. I mean, if I do:
function ErasableItem({ id }) {
const { isLoading, error, deleteItem } = useDeleteItem(id);
useHeaderRightLoadingIndicator(isLoading);
return <Text onPress={deleteItem}>Delete!</Text>;
}
As the item will be unmounted from the screen, the useEffect of the useHeaderRightLoadingIndicator will not be called the last time, when isLoading toggles from true to false.
In order to fix that, I will have to run a cleanup function, like this:
export default function useHeaderRightLoadingIndicator(loading = false) {
const navigation = useNavigation();
const renderLoading = useCallback(() => {
if (!loading) return null;
return (
<Loading
size={20}
style={styles.loadingIndicator}
/>
);
}, [loading]);
useEffect(() => {
navigation.setOptions({
headerRight: renderLoading,
});
return () => {
// cleanup
navigation.setOptions({ headerRight: null });
};
}, [navigation, renderLoading]);
}
Something that makes me doubt, since if I had delegated the delete operation to the screen, which is not unmountable, I would not have any problem and I would not have to execute that cleanup function.
What is the logic to follow when delegating responsibilities? Is my delegation incorrect in React?

React component is rendering old state before getting new data

When the component first renders it gets from the switchcase (enters ALL case because its the default value) on the usePositions hook, the value for positions and I set them there, and return them to the Positions controller.
The problem comes when the selectedClient changes from ALL to TODAY (its a context value, I change it in a Sidebar component somewhere else) and before entering the switch case in TODAY value to get the positions of today, I noticed the Positions component already rendered the old state of ALL positions again! Then a second later it renders correctly the todays positions.
I noticed this because my browser on my network tab shows some calls to the server that IndividualPosition makes it means that it rendered
This is my component where it calls the usePositions hook
export const Positions = () => {
const { selectedClient } = useSelectedClientValue();
const { loading, setLoading } = useLoadingValue();
const { positions } = usePositions(selectedClient);
const clientName =
typeof selectedClient === "string" ? selectedClient : selectedClient.name;
useEffect(() => {
setLoading(false);
}, [positions]);
let positionsView = (
<ul className="positions__list">
{positions.map((position) => (
<IndividualPosition position={position} key={position.positionId} />
))}
</ul>
);
return (
<div className="positions" data-testid="positions">
{!loading ? (
<>
<div className="positions__header">
<h2 data-testid="client-name">{clientName}</h2>
</div>
{positionsView}
</>
) : (
<div className="loading-main-window">
<Spinner />
</div>
)}
</div>
);
};
This is the hook where I fetch the data
export const usePositions = selectedClient => {
const [positions, setPositions] = useState([]);
const {setLoading} = useLoadingValue()
useEffect(() => {
setLoading(true);
switch (selectedClient) {
case 'ALL':
getPositions().then(pos => {
setPositions(pos);
});
break;
case 'TODAY':
getTodayPositions().then(pos => {
setPositions(pos);
});
break;
default:
break;
}
}, [selectedClient]);
return {positions, setPositions};
};
The useEffect runs each time the selectedClient change
It looks like the component renders again before getting the todays data and thats why it shows the old state before getting the new data, but I thought that could be avoided with the loading flag
Basically:
-Positions renders, the hook fetches allPositions, its fine
-If I change in the sidebar the value of the selectedClient context value, the Positions components renders again, rendering the IndividualComponent but with the state of allPositions.
- Instead it should wait till todaysPositions fetches to show the new state (loading should do that)
I already tried having a loading local state (my loading is a context value)
Moving the loading in the useEffects on my local component instead of my hook
Setting loading to false inside the hook after fetching the data
Any ideas?

ReactJS Wrong Component gets removed from DOM

I have three files: ShopsContainer.js ShopsComponent.js and ShopsItemComponent.js
ShopsContainer maintains an array of shop items in local state that gets passed down into ShopsComponent as props. ShopsComponent then maps through the items array that is being received as props and renders a ShopsItemComponent for each item in the array.
Within my ShopsContainer file, I have a method that removes a shop item from state using the following code:
removeShop = (shopAccount) => {
this.setState(prevState => ({
items: prevState.items.filter(shop => {
return shop.shopAccount !== shopAccount
})
}));
}
When this happens, the correct item is removed from the items array in state, however, whatever the last ShopItem is that is in the DOM at the time of the removeShop call will get removed no matter if it is the correct item that should be removed or not. In other words, when removeShop gets called and the items array in state gets updated correctly, the wrong ShopItemComponent gets removed from the DOM.
What I would like to happen (or what I think should happen) is when removeShop gets called, that shop gets removed from the items array in state and ShopsContainer re-renders causing ShopsComponent to re-render with the updated props being received. And lastly ShopsComponent would map through the newly updated items array in props displaying a `ShopItemComponent for the correct items. Perhaps the problem has to do with the props being updated?
My code is as follows:
ShopsContainer.js
class ShopsContainer extends Component {
constructor() {
this.state = {
items: null
}
this.getAll();
this.removeShop = this.removeShop.bind(this);
}
getAll = () => {
// API request that fetches items and updates state
}
removeShop = (shopAccount) => {
this.setState(prevState => ({
items: prevState.items.filter(shop => {
return shop.shopAccount !== shopAccount
})
}));
}
render() {
return (
<div>
{this.state.items ? <ShopComponent items={this.state.items} removeShop={this.removeShop} /> : <div><h1>Loading...</h1></div>}
</div>
);
}
}
ShopsComponent.js
class ShopsComponent extends Component {
constructor() {
this.handleRemove = this.handleRemove.bind(this);
}
handleRemove = (shopAccount) => {
this.props.removeShop(shopAccount);
}
render() {
return (
<React.Fragment>
<Header />
{this.props.items.map((shopItem, i) => {
return (<ShopItemComponent key={i} item={shopItem} removeShop={this.handleRemove} />);
})}
</React.Fragment>
);
}
}

Your code is working great, but you only has one mistake , your ShopComponent is assign index as a key for each ShopItemComponent and react is tracking those indexes to update the correct component, so you need to set key as a unique value between items, then I realize that shopAccount should be your id for each item.
The solution code is below.
class ShopsComponent extends Component {
handleRemove = (shopAccount) => {
this.props.removeShop(shopAccount);
}
render() {
return (
<React.Fragment>
<Header />
{this.props.items.map((shopItem) => <ShopItemComponent key={shopItem.shopAccount} item={shopItem} removeShop={this.handleRemove} />)}
</React.Fragment>
);
}
}
I hope you can find useful.
Note, when you are using a arrow function into your class, don't bind that method into the constructor, so remove it, because
handleRemove = (shopAccount) => {
this.props.removeShop(shopAccount);
}
is already binded.

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