I am having a ton of react hooks a missing dependency warnings for my redux functions that are called in useEffect to fetch data. The official documentation and dan abramov's post about this issue doesn't help me so much on what to do. Since, in summary, the recommendations are ;
move the function inside the useEffect if it is used in an effect only (I would rather not because I am using these functions elsewhere as well.)
move the function outside the component if it is not using any props or state ( they are already declared in their own store and I bring them to the component's context via connecting tag. And so they appear on the props object of the component. So this solution is also not applicable.
wrap them with useCallback so you can add them in the dependency array and it won't lead to an infinite loop because the functions will not get a new reference on each render. ( this sounds a little bit hacky solution to me. But if not please enlighten me. So it will look like this;
const { fetchMe } = props
useEffect(() => {
fetchMe()
}, [])
will turn into this
const { fetchMe } = props
const initFetchMe = useCallback(() => {
return dispatch(fetchMe())
}, [dispatch])
useEffect(() => {
initFetchMe();
}, [initFetchMe]);
When I look at the stackoverflow some candidate solution for this to refactor connect tag with redux hooks (useDispatch and useSelector) I am more leaning towards this solution but I couldn't find a good migration guide, I don't want to be introducing lots of bugs at once to the repo. So this example component:
import React, {useEffect} from 'react'
import Stats from '../components/Stats'
import {useTranslation} from 'react-i18next'
import {connect} from 'react-redux'
import {getEmployeesTotal} from '../stores/employees'
import {getVisitorsTotal} from '../stores/visitors'
import {getCardsTotal} from '../stores/cards'
function SimpleStats(props) {
const {t} = useTranslation()
useEffect(() => {
props.getEmployeesTotal()
props.getCardsTotal()
props.getVisitorsTotal()
}, [])
return (
<React.Fragment>
<div className="container">
<div className="row quick-stats justify-content-md-center">
<Stats
className="col"
value={
props.get_employees_total !== null ? props.get_employees_total.meta.total : '...'
}
description={t('stats.EmployeesTotal')}
/>
<Stats
className="col"
value={
props.get_visitors_total !== null ? props.get_visitors_total.meta.total : '...'
}
description={t('stats.VisitorsTotal')}
/>
<Stats
className="col"
value={props.get_cards_total !== null ? props.get_cards_total.meta.total : '...'}
description={t('stats.CardsTotal')}
/>
</div>
</div>
</React.Fragment>
)
}
const mapStateToProps = (state) => ({
get_employees_total: state.employees.get_employees_total.success,
get_visitors_total: state.visitors.get_visitors_total.success,
get_cards_total: state.cards.get_cards_total.success,
})
export default connect(mapStateToProps, {
getEmployeesTotal,
getVisitorsTotal,
getCardsTotal,
})(SimpleStats)
becomes this:
import React, {useEffect} from 'react'
import Stats from '../components/Stats'
import {useTranslation} from 'react-i18next'
import {connect} from 'react-redux'
import {getEmployeesTotal} from '../stores/employees'
import {getVisitorsTotal} from '../stores/visitors'
import {getCardsTotal} from '../stores/cards'
function SimpleStats(props) {
const {t} = useTranslation()
const get_employees_total = useSelector((state)=>state.employees.get_employees_total.success)
const get_visitors_total = useSelector((state) => state.visitors.get_visitors_total.success )
const get_cards_total = useSelector((state) => state.cards.get_cards_total.success)
useEffect(() => {
dispatch(getEmployeesTotal())
dispatch(getCardsTotal())
dispatch(getVisitorsTotal())
}, [dispatch])
return (
<React.Fragment>
<div className="container">
<div className="row quick-stats justify-content-md-center">
<Stats
className="col"
value={
props.get_employees_total !== null ? props.get_employees_total.meta.total : '...'
}
description={t('stats.EmployeesTotal')}
/>
<Stats
className="col"
value={
props.get_visitors_total !== null ? props.get_visitors_total.meta.total : '...'
}
description={t('stats.VisitorsTotal')}
/>
<Stats
className="col"
value={props.get_cards_total !== null ? props.get_cards_total.meta.total : '...'}
description={t('stats.CardsTotal')}
/>
</div>
</div>
</React.Fragment>
)
}
export default SimpleStats
Would you enlighten me on which solution is better? Does my migration to redux-hooks have problems?
Related
Can you use useState (and other react hooks?) with Server Side Rendering? Everytime I am trying to run the code below I get the error TypeError: Cannot read property 'useState' of null. However, when I comment out the getServerSideProps function at the very bottom I have no problem running the code as intended. So my questions is can useState be used with Server Side Rendering in nextjs? If the answer is yes, then where am I going wrong in the code below?
import React from "react";
import { useRouter } from "next/router";
import useSelectedGenreInfoExtractor from "../../hooks/useSelectedGenreInfoExtractor";
import { useState } from "react";
import { useEffect } from "react";
import Navbar from "../../components/Navbar";
import useFetchTrendingCatagory from "../../hooks/useFetchTrendingCatagory";
import useFetchTopRatedCatagory from "../../hooks/useFetchTopRatedCatagory";
import useFetchMovieGenreResults from "../../hooks/useFetchMovieGenreResults";
import Moviegenreresults from "../../components/Moviegenreresults";
export default function genre(props) {
const [myresultsfromhook, setMyresultsfromhook] = useState();
const [myreturnedmovies, setMyreturnedmovies] = useState();
const router = useRouter();
const { genre } = router.query;
if (genre == "Trending") {
let mymovies = useFetchTrendingCatagory();
console.log("This is a log of my props", props);
return (
<div>
{/* <Navbar /> */}
<div>{genre}</div>
<Moviegenreresults movies={mymovies} />
</div>
);
} else if (genre == "Top Rated") {
let mymovies = useFetchTopRatedCatagory();
return (
<div>
{/* <Navbar /> */}
<div>{genre}</div>
<Moviegenreresults movies={mymovies} />
</div>
);
} else {
let mymovies = useFetchMovieGenreResults(genre);
return (
<div>
{/* <Navbar /> */}
<div>{genre}</div>
<Moviegenreresults movies={mymovies} />
</div>
);
}
}
export async function getServerSideProps(context) {
if (context.params.genre == "Trending") {
let mymovies = useFetchTrendingCatagory();
return {
props: {
results: mymovies.results,
},
};
} else if (context.params.genr == "Top Rated") {
let mymovies = useFetchTopRatedCatagory();
return {
props: {
results: mymovies.results,
},
};
} else {
let mymovies = useFetchMovieGenreResults(genre);
return {
props: {
results: mymovies.results,
},
};
}
}
I think fundamentally the problem is the way you are using getServerSideProps.
Even thought the answer is you can not use useState inside getServerSideProps because this function run in the server, it is important to understand what getServerSideProps does and when, I think you can find very clear explanation about that in next docs.
https://nextjs.org/docs/basic-features/data-fetching/get-server-side-props
Inside getServerSideProps use axios or the fetch api to get your data and pass it to the props.
I am not 100% sure but I thinnk inn your case you can also use Promise.all() to get the data from those three api calls.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all
useState should be inside the component, it is a React hook. serverside functions are independent of React components.
I think the issue is the name of the component should be with capital letter:
// not genre
export default function Genre(props)
I have a simple react app in which i have to use useContext.
(btw im using vite + react)
here is my code for Context.jsx
import React, {useContext} from 'react';
const emailContext = React.createContext();
export const useEmail = () => useContext(emailContext);
export const emailProvider = ({children}) => {
const currentUser = "None";
const value = {
currentUser
}
return(
<emailContext.Provider value={value}>
{children}
</emailContext.Provider>
)
}
and heres how i am using the context
import "./styles.css";
import { useEmail } from "./Context/Context"
export default function App() {
const {currentUser} = useEmail();
return (
<div className="App">
<h1>Hello CodeSandbox {currentUser}</h1>
<h2>Start editing to see some magic happen!</h2>
</div>
);
}
I am sure why I am getting error in this code.
some of the errors that I am getting
_useEmail is undefined (latest)
currentUser user is undefined
thing i have tried
Initialized createContext with some initial value (only intial value is visible).
using useContext() directy in the App.js (useContext(emailContext) return undefined)
instead of {children} used <children/>.
used useState instead of const currentUser in emailProvider
I am getting same problem even when I use typescript.
but none of the above helped.
You should wrapping app with <emailProvider></emailProvider> to using data in value={value}. Now it gets undefined from const emailContext = React.createContext();
Below code may help you analyse the flow , also check link for more details https://medium.com/technofunnel/usecontext-in-react-hooks-aa9a60b8a461
use useContext in receiving end
import React, { useState } from "react";
var userDetailContext = React.createContext(null);
export default function UserDetailsComponent() {
var [userDetails] = useState({
name: "Mayank",
age: 30
});
return (
<userDetailContext.Provider value={userDetails}>
<h1>This is the Parent Component</h1>
<hr />
<ChildComponent userDetails={userDetails} />
</userDetailContext.Provider>
);
}
function ChildComponent(props) {
return (
<div>
<h2>This is Child Component</h2>
<hr />
<SubChildComponent />
</div>
);
}
function SubChildComponent(props) {
var contextData = React.useContext(userDetailContext);
return (
<div>
<h3>This is Sub Child Component</h3>
<h4>User Name: {contextData.name}</h4>
<h4>User Age: {contextData.age}</h4>
</div>
);
}
I'm struggling to understand how to proceed with a small React app I am making.
I have a budget tracker, where you can add costs (mortgage, bills etc.) and they have a cost value. Each time you add, edit or delete one of these, I want the global state to change, which is stored in a context.
I basically have a 'remaining balance' value, that I want to recalculate each time something changes.
I figured I'd use a life cycle method or useEffect, but when I use that in my App.js (so that it watches for changes in all subcomponents), I can't get it to work, because the life cycle method is calling a method from my Context, but because it's not wrapped in the provider, it can't access the method in the Context.
Is this a common problem and is there are recommended way to fix it? I can't seem to find a similar problem on the GoOgLe.
App.js:
import React, { useState, useContext, useEffect } from "react";
import "./css/main.css";
import Header from "./layout/Header";
import BudgetInfo from "./components/BudgetInfo";
import PaymentForm from "./components/PaymentForm";
import CostToolbar from "./components/CostToolbar";
import Costs from "./components/Costs";
import BudgetContext from "./context/budgetContext";
import BudgetState from "./context/BudgetState";
const App = () => {
const budgetContext = useContext(BudgetContext);
const { updateBalance } = budgetContext;
useEffect(() => {
updateBalance();
});
return (
<BudgetState>
<Header darkModeToggle={toggleDarkMode} />
<main
className={"main-content" + (darkMode.darkMode ? " dm-active" : "")}
>
<div className="wrap content-wrap">
<BudgetInfo />
<PaymentForm />
<CostToolbar />
<Costs />
</div>
</main>
</BudgetState>
);
};
export default App;
You need to wrap the App component. Try the simple example.
import React, { useEffect, useContext } from 'react';
import ThemeContext from './../context/context';
const Sample = () => {
const context = useContext(ThemeContext);
useEffect(() => {
console.log(context,'--')
},[])
return(
<ThemeContext.Consumer>
{color => (
<p style={{ color }}>
Hello World
</p>
)}
</ThemeContext.Consumer>
)
}
export default Sample;
I'm trying to learn to create hooks so I can re-use data that I have to change in different components.
I'm using Material UI's Tabs and need to use useTab, a custom hook to change the tab id.
import React, { useContext } from 'react';
import { ProductsContext } from './ProductsContext';
import AppBar from '#material-ui/core/AppBar';
import Tabs from '#material-ui/core/Tabs';
import Tab from '#material-ui/core/Tab';
import { useTab } from '../../hooks/tab';
const ProductsNav = () => {
const {products, categories, loading} = useContext(ProductsContext);
const [tabValue] = useTab(0);
const handleTabChange = (e, newTabValue) => {
useTab(newTabValue);
}
return (
<div className="products">
<AppBar position="static">
<Tabs value={tabValue} onChange={ handleTabChange }>
{
Array.from(categories).map(category => (
!category.unlisted && (<Tab label={category.title} key={category.id}/>)
))
}
</Tabs>
</AppBar>
</div>
);
};
export default ProductsNav;
I know it does this with child functions in the docs, but I'm trying to not just copy and paste and do it in my own way.
Here is my custom useTab hook:
import {useState, useEffect} from 'react';
export const useTab = (selectedTab) => {
const [tabValue, setTabValue] = useState(0);
useEffect(() => {
setTabValue(selectedTab);
}, []);
return [tabValue];
}
I'm of course getting an error I can't use a hook inside of a function, but I'm confused how else to do this.
How can I change tabValue from useTabs?
The error is probably here:
const handleTabChange = (e, newTabValue) => {
useTab(newTabValue);
}
You're violating one of the primary Rules of Hooks:
Don’t call Hooks inside loops, conditions, or nested functions.
Instead, always use Hooks at the top level of your React function.
The reason for this rule is a bit complex but it basically boils down to the idea that hooks should only be called at the top level of a React functional component because they must be guaranteed to run every time the component function is run.
Hence why you're getting an error "I can't use a hook inside of a function"...
At any rate, it is unclear why you are using a custom hook with a useEffect() here. That seems completely unnecessary - a regular useEffect() hook inside of your nav component should more than suffice:
const ProductsNav = () => {
const {products, categories, loading} = useContext(ProductsContext);
const [tabValue, setTabValue] = useState(0);
const handleTabChange = (e, newTabValue) => {
setTabValue(newTabValue);
}
return (
<div className="products">
<AppBar position="static">
<Tabs value={tabValue} onChange={ handleTabChange }>
{
Array.from(categories).map(category => (
!category.unlisted && (<Tab label={category.title} key={category.id}/>)
))
}
</Tabs>
</AppBar>
</div>
);
};
I'm having an issue where react-loadable is causing one of my input components to re-render and lose focus after a state update. I've done some digging and I can't find anyone else having this issue, so I think that I'm missing something here.
I am attempting to use react-loadable to dynamically include components into my app based on a theme that the user has selected. This is working fine.
./components/App
import React from 'react';
import Loadable from 'react-loadable';
/**
* Import Containers
*/
import AdminBar from '../../containers/AdminBar';
import AdminPanel from '../../components/AdminPanel';
import 'bootstrap/dist/css/bootstrap.css';
import './styles.css';
const App = ({ isAdmin, inEditMode, theme }) => {
const MainContent = Loadable({
loader: () => import('../../themes/' + theme.name + '/components/MainContent'),
loading: () => (<div>Loading...</div>)
});
const Header = Loadable({
loader: () => import('../../themes/' + theme.name + '/components/Header'),
loading: () => (<div>Loading...</div>)
});
return (
<div>
{
(isAdmin) ? <AdminBar
className='admin-bar'
inEditMode={inEditMode} /> : ''
}
<Header
themeSettings={theme.settings.Header} />
<div className='container-fluid'>
<div className='row'>
{
(isAdmin && inEditMode) ? <AdminPanel
className='admin-panel'
theme={theme} /> : ''
}
<MainContent
inEditMode={inEditMode} />
</div>
</div>
</div>
);
};
export default App;
./components/AdminPanel
import React from 'react';
import Loadable from 'react-loadable';
import './styles.css';
const AdminPanel = ({ theme }) => {
const ThemedSideBar = Loadable({
loader: () => import('../../themes/' + theme.name + '/components/SideBar'),
loading: () => null
});
return (
<div className='col-sm-3 col-md-2 sidebar'>
<ThemedSideBar
settings={theme.settings} />
</div>
);
};
export default AdminPanel;
This is what my <ThemedSideBar /> components looks like:
./themes/Default/components/SideBar
import React from 'react';
import ThemeSettingPanel from '../../../../components/ThemeSettingPanel';
import ThemeSetting from '../../../../containers/ThemeSetting';
import './styles.css';
const SideBar = ({ settings }) => {
return (
<ThemeSettingPanel
name='Header'>
<ThemeSetting
name='Background Color'
setting={settings.Header}
type='text'
parent='Header' />
<ThemeSetting
name='Height'
setting={settings.Header}
type='text'
parent='Header' />
</ThemeSettingPanel>
);
};
export default SideBar;
./components/ThemeSettingPanel
import React from 'react';
import { PanelGroup, Panel } from 'react-bootstrap';
const ThemeSettingPanel = ({ name, children }) => {
return (
<PanelGroup accordion id='sidebar-accordion-panelGroup'>
<Panel>
<Panel.Heading>
<Panel.Title toggle>{name}</Panel.Title>
</Panel.Heading>
<Panel.Body collapsible>
{children}
</Panel.Body>
</Panel>
</PanelGroup>
);
};
export default ThemeSettingPanel;
./containers/ThemeSetting
import React, { Component } from 'react';
import { connect } from 'react-redux';
import { themeSettingChange } from '../App/actions';
import ThemeSetting from '../../components/ThemeSetting';
class ThemeSettingContainer extends Component {
constructor(props) {
super(props);
this.handleOnChange = this.handleOnChange.bind(this);
}
handleOnChange(name, parent, value) {
const payload = {
name: name,
parent,
value: value
};
this.props.themeSettingChange(payload);
}
render() {
return (
<ThemeSetting
name={this.props.name}
setting={this.props.setting}
parent={this.props.parent}
type={this.props.type}
handleOnChange={this.handleOnChange} />
);
}
}
//----Redux Mappings----//
const mapStateToProps = (state) => ({
});
const mapDispatchToProps = {
themeSettingChange: (value) => themeSettingChange(value)
};
export default connect(mapStateToProps, mapDispatchToProps)(ThemeSettingContainer);
./component/ThemeSetting
import React from 'react';
import TextField from '../common/TextField';
import './styles.css';
const ThemeSetting = ({ name, setting, type, parent, handleOnChange }) => {
return (
<div className='row theme-setting'>
<div className='col-xs-7'>
{name}
</div>
<div className='col-xs-5'>
{
generateField(type, setting, name, parent, handleOnChange)
}
</div>
</div>
);
};
function generateField(type, setting, name, parent, handleOnChange) {
const value = setting ? setting[name] : '';
switch (type) {
case 'text':
return <TextField
value={value}
name={name}
parent={parent}
handleOnChange={handleOnChange} />;
default:
break;
}
}
export default ThemeSetting;
./components/common/TextField
import React from 'react';
import { FormControl } from 'react-bootstrap';
const TextField = ({ value, name, parent, handleOnChange }) => {
return (
<FormControl
type='text'
value={value}
onChange={(e) => {
handleOnChange(name, parent, e.target.value);
}} />
);
};
export default TextField;
When a field inside of my Admin Panel is updated, a state change is triggered. It seems like this triggers react-loadable to re-render my <ThemedSideBar /> components which destroys my input and creates a new one with the updated value. Has anyone else had this issue? Is there a way to stop react-loadable from re-rendering?
EDIT: Here is the requested link to the repo.
EDIT: As per conversation in the comments, my apologies, I misread the question. Answer here is updated (original answer below updated answer)
Updated answer
From looking at the react-loadable docs, it appears that the Loadable HOC is intended to be called outside of a render method. In your case, you are loading ThemedSideBar in the render method of AdminPanel. I suspect that the change in your TextEdit's input, passed to update your Redux state, and then passed back through the chain of components was causing React to consider re-rendering AdminPanel. Because your call to Loadable was inside the render method (i.e. AdminPanel is a presentational component), react-loadable was presenting a brand new loaded component every time React hit that code path. Thus, React thinks it needs to destroy the prior component to appropriately bring the components up to date with the new props.
This works:
import React from 'react';
import Loadable from 'react-loadable';
import './styles.css';
const ThemedSideBar = Loadable({
loader: () => import('../../themes/Default/components/SideBar'),
loading: () => null
});
const AdminPanel = ({ theme }) => {
return (
<div className='col-sm-3 col-md-2 sidebar'>
<ThemedSideBar
settings={theme.settings} />
</div>
);
};
export default AdminPanel;
Original answer
It seems that your problem is likely related to the way you've built TextField and not react-loadable.
The FormControl is taking value={value} and the onChange handler as props. This means you've indicated it is a controlled (as opposed to uncontrolled) component.
If you want the field to take on an updated value when the user types input, you need to propagate the change caught by your onChange handler and make sure it gets fed back to the value in the value={value} prop.
Right now, it looks like value will always be equal to theme.settings.Height or the like (which is presumably null/empty).
An alternative would be to make that FormControl an uncontrolled component, but I'm guessing you don't want to do that.