We Keep Coding

SonarQube "Do not define components during render" with MUI/TS but can't send component as prop

I am getting the following error during sonarqube scan:
Do not define components during render. React will see a new component type on every render and destroy the entire subtree’s DOM nodes and state. Instead, move this component definition out of the parent component “SectionTab” and pass data as props. If you want to allow component creation in props, set allowAsProps option to true.
I understand that it says that I should send the component as a prop from the parent, but I don't want to send the icon everytime that I want to use this component, is there another way to get this fixed?
import Select from "#mui/material/Select";
import { FontAwesomeIcon } from "#fortawesome/react-fontawesome";
import { faAngleDown } from "#fortawesome/pro-solid-svg-icons/faAngleDown";
const AngleIcon = ({ props }: { props: any }) => {
return (
<FontAwesomeIcon
{...props}
sx={{ marginRight: "10px" }}
icon={faAngleDown}
size="xs"
/>
);
};
const SectionTab = () => {
return (
<Select
id="course_type"
readOnly={true}
IconComponent={(props) => <AngleIcon props={props} />}
variant="standard"
defaultValue="cr"
disableUnderline
/>
);
};
export default SectionTab;

What can you do:
Send the component as the prop:
IconComponent={AngleIcon}
If you need to pass anything to the component on the fly, you can wrap it with useCallback:
const SectionTab = () => {
const IconComponent = useCallback(props => <AngleIcon props={props} />, []);
return (
<Select
id="course_type"
readOnly={true}
IconComponent={IconComponent}
variant="standard"
defaultValue="cr"
disableUnderline
/>
);
};
This would generate a stable component, but it's pretty redundant unless you need to pass anything else, and not via the props. In that case, a new component would be generated every time that external value changes, which would make it unstable again. You can use refs to pass values without generating a new component, but the component's tree won't be re-rendered to reflect the change in the ref.
const SectionTab = () => {
const [value, setValue] = useState(0);
const IconComponent = useCallback(
props => <AngleIcon props={props} value={value} />
, []);
return (
<Select
id="course_type"
readOnly={true}
IconComponent={IconComponent}
variant="standard"
defaultValue="cr"
disableUnderline
/>
);
};

Can you pass in a useState function into a component on initialization?

I'm using the useState hook to manage rendering components on screen. I want to initialize it with a component while passing in the useState function to set the screen into the component.
Here is my App.js. The error I get is in regards to passing a function into itself on initialization.
function App() {
//useState hooks to determine which component should render
const [screenLoaded, loadScreen] = useState(() => {
<Home setLoadedScreen = {loadScreen}/>
})
return (
<div className="App">
{screenLoaded}
</div>
);
}

The default value for useState is always in the parentheses, no curly braces are needed in this case. const [state, setState] = useState(default). This state could be change in the future with setState(new value).

one simple method is to give your screen a name for example
<Home /> === "home-screen"
<About /> === "about-screen"
so when you pass the setState method of loadScreen into the component, you can switch them by setting the string, for example if you're in home screen and you want to switch to about screen, you'd write
setLoadedScreen("about-screen")
function App(){
const [screenLoaded, loadScreen] = useState("home-screen")
return (
<div className="App">
{screenLoaded === "home-screen" && <Home setLoadedScreen = "loadedScreen" />}
{screenLoaded === "about-screen" && <About setLoadedScreen = "loadedScreen" />}
</div>
);
}

How to share props to a different route using react-router-dom?

I am trying to share my props (data, saveWorkButtonClicked, updateFBRDB) from <ProjectPage /> component route to <Indent /> component route.
But getting the following error:
Uncaught DOMException: Failed to execute 'pushState' on 'History': async (data, setSpinner, updateFBRDB) => {
setSpinner && setSpinner(true);
let rawRoomData = String.raw`${J...<omitted>...
} could not be cloned.
App.js
<Router>
<Switch>
<Route path="/ProjectPage/:projectId" exact component={ProjectPage} />
<Route path="/Indent/" render={(props) => <Indent {...props} />} />
</Switch>
</Router>
ProjectPage.js
history.push("/Indent/",
{
data: { ...project, rooms: project.rooms, ProjectId: project.ProjectId, ClientName: project.ClientName, Address: project.Address, AmountRecieved: project.AmountReceived, SiteEngineerId: project.SiteEngineersId },
saveWorkButtonClicked,
updateFBRDB,
}
)
// saveWorkButtonClicked & updateFBRDB are API calls which will be called in <Indent />
Indent.js
export default function Indent({ data, saveWorkButtonClicked, updateFBRDB }) {
console.log('data in indent', data)
}
NOTE: Please give solutions where this can be implemented without Context/ Redux/ Mobx. Also, I am using react-router-dom v5.2.0

I would suggest an workaround. Have a state which keeps track of when you want to move to next page, so that we can use Redirect component conditionally with your desired data as props.
App.js
<Router>
<Switch>
<Route path="/ProjectPage/:projectId" exact component={ProjectPage} />
</Switch>
</Router>
ProjectPage.js
const [isDone, setIsDone] = useState(false);
const handleClick = () => {
// Do all your works, when you want to `push` to next page, set the state.
setIsDone(true);
}
if(isDone) {
return (
<>
<Route path="/Indent"
render={ props =>
<Indent
{...props}
data={...}
saveWorkButtonClicked={saveWorkButtonClicked}
updateFBRDB={updateFBRDB}
/>
}
/>
<Redirect to="/Indent" />
</>
);
}
return (
<div>Your Normal Profile Page goes here</div>
)

If you want to "share" props, you need to do one of two things. Either have the receiving component be a child of the propsharing component - in which case you can pass them as props directly. Else, you would need to pass them as state via a common ancestor component, which you would need to update by sending a callback down to the component that will update the state.

You can pass state to location with this format
const location = {
pathname: '/Indent/',
state: {
data: { ...project, rooms: project.rooms, ProjectId: project.ProjectId, ClientName: project.ClientName, Address: project.Address, AmountRecieved: project.AmountReceived, SiteEngineerId: project.SiteEngineersId },
saveWorkButtonClicked,
updateFBRDB,
}
}
history.push(location)
And then using withRouter to receive location values
import { withRouter } from 'react-router'
function Indent({ location }) {
const { state } = location
const { data, saveWorkButtonClicked, updateFBRDB } = state || {}
return <></>
}
export default withRouter(Indent)

how to Stop rerendering of entire component onChange event on input text field in reactJs

I m new to reactJs and i m creating user Authentication functionality. I have two components one is header which has navbar and it contains react-router routers and the other is login component which has two input fields ... The problem with login component is when i start typing in input field it loses focus after each character typed i know it is rerendering the whole component but i don't know how to solve this problem
header.js
changeName = (e) => {
this.setState({name : e.target.value})
}
changePass = (e) => {
this.setState({password:e.target.value})
}
login = () => {
var name = this.state.name;
var password = this.state.password
var mysession;
$.ajax({
url : 'http://localhost:4000/login',
type : "POST",
data : {username:name,password:password},
success : function(data){
if(data == true){
this.setState({sessionFlag:true})
$('#home')[0].click();
}
else {
this.setState({sessionFlag:false})
}
}.bind(this)
})
}
render(){
const {name,password} = this.state;
return (
<Router>
<div>
<Route path="/login" exact component={()=><Login
onClickHandle={this.login.bind(this)}
onChangeName={this.changeName.bind(this)}
onChangePass={this.changePass.bind(this)}
name={name}
password = {password} />} />
</div>
</Router>
)
}
login.js
render(){
return (
<form className="form-horizontal" method ="post">
<input
type="text"
onChange={this.props.onChangeName}
value={this.props.name}/>
<input type="text"
onChange={this.props.onChangePass}
value={this.props.password} />
<input type="button"
value="Login"
onClick={this.props.onClickHandle} />
</form>
)
}

The main issue is the manner in which you are specifying your Login component:
<Route
path="/login"
exact
component={() => (
<Login
onChangeName={this.changeName.bind(this)}
onChangePass={this.changePass.bind(this)}
name={this.state.name}
password={this.state.password}
/>
)}
/>
Using this syntax causes the child of the Route to look like a brand-new type of component with each rendering (since it will be a new arrow function instance each time) so the previous Login component will be completely unmounted and the new one mounted.
From https://reactrouter.com/web/api/Route/component:
When you use component (instead of render or children, below) the router uses React.createElement to create a new React element from the given component. That means if you provide an inline function to the component prop, you would create a new component every render. This results in the existing component unmounting and the new component mounting instead of just updating the existing component. When using an inline function for inline rendering, use the render or the children prop (below).
Here is an example using the render-func approach:
Header.js
import React from "react";
import { BrowserRouter as Router, Route, Link } from "react-router-dom";
import Login from "./Login";
class Header extends React.Component {
constructor(props) {
super(props);
this.state = { name: "", password: "" };
this.changeName = this.changeName.bind(this);
this.changePass = this.changePass.bind(this);
}
changeName = (e) => {
this.setState({ name: e.target.value });
};
changePass = (e) => {
this.setState({ password: e.target.value });
};
render() {
return (
<Router>
<div>
<div>
<Link to="/login">Login</Link>
</div>
<Route
path="/login"
exact
render={() => (
<Login
onChangeName={this.changeName}
onChangePass={this.changePass}
name={this.state.name}
password={this.state.password}
/>
)}
/>
</div>
</Router>
);
}
}
export default Header;

Component only rending if I start the flow from the homepage

I am having an issue with my application. My user component only loads UserCard when I start the application from the homepage then click users link there... if I just refresh the users URL... UserCard doesn't get loaded which means something is wrong with my this.props.users. I do see that in chrome it says: Value below was evaluated just now when I refresh but when I go through the flow it doesn't say that. Any help will be appreciated.
App.js
class App extends Component {
constructor(props) {
super(props);
this.state = {
users: []
};
}
componentDidMount() {
users = []
axios.get('/getall').then((res) => {
for(var d in res.data) {
users.push(new User(res.data[d]));
}
});
this.setState({ users });
}
render() {
const { users } = this.state;
return (
<Router history={history}>
<Switch>
<PrivateRoute exact path="/" component={Home} />
<Route exact path='/users' render={(props) => <Users {...props} users={users} />}/>
</Switch>
</Router>
)
}
}
PrivateRoute:
export const PrivateRoute = ({ component: Component, ...rest }) => (
<Route {...rest} render={props => (
<Component {...props} /> )} />
)
User.js
export default class Users extends Component {
render() {
console.log(this.props.users);
return (
<Row>
{this.props.users.map(u =>
<UserCard key={u.name} user={u}/>
)}
</Row>
);
}
}
export class User {
constructor(obj) {
for (var prop in obj){
this[prop] = obj[prop];
}
}
getURLName() {
return this.name.replace(/\s+/g, '-').toLowerCase();
}
}
class UserCard extends Component {
render() {
return (
<Link to={'/users/' + this.props.user.getURLName()} >
<div>
// Stuff Here
</div>
</Link>
);
}
}

As per the comments:
The issue here is how you're setting state. You should never modify state directly since this will not cause the component to rerender See the react docs
Some additional thoughts unrelated to the question:
As per the comments - use function components whenever possible, especially with hooks on the way
There is probably no need to create a User class, only to new up little user objects. Simply use plain old JS objects and calculate the link url right in the place its used:
render() {
const { user } = this.props
return <Link to={`/users/${user.name.replace(/\s+/g, '-').toLowerCase()}`} />
}
It might be a good idea to start using a linter such as eslint. I see that you're declaring users = [] without using let or const (don't use var). This is bad practice since creating variables in this way pollutes the global name space. Linters like eslint will help you catch issues like this while you're coding.