I am new to React and recently started working on it. I know that we cannot change the components properties using the props.
I want to know how can we change the properties of Component?
Below is my code:
Courses.jsx
function Courses(){
return (
<div className="courses">
<h1>Ongoing Courses</h1>
<div className="row">
{CourseData.map((value,index)=>{
return (
<div className="col-md-3">
<Card title={value.title} completed={value.completed} content={value.content} value="Resume !" key={index} id={index} />
</div>
);
})}
</div>
</div>
);
}
Here above i am having a Array of Data named as courseData, I am mapping it on a Card component.
Card.jsx:
function Card(props){
function handleClick(){
}
return (
<div className="card">
<div className="card-body">
<h2 className="card-title">{props.title}</h2>
{props.content}
<br/>
<button className="btn btn-danger" > {props.value}</button>
</div>
</div>
);
}
the CourseData has following properties :
courseData : [{
key,
title,
completed
content}]
I simply want that when ever the button present is card gets clicked then the completed attribute of courseData changed to some different value that is passed through the props .
I have tried a lot but not able to do .
Any help regarding this will be helpful for me .
courseData.jsx:
const notes = [{
key: 1,
title: "some Text",
completed:false,
content: "some Text"
},
{
key: 2,
title: "some Text",
completed:false,
content: "some Text"
}]
export default notes;
Add CourseData to the state of the Courses component. Then add a method to adjust the data there. Pass the method throught props that will be called when clicking button in the Card component:
function Courses() {
const [courseData, setCourseData] = useState(CourseData);
const updateCourseData = (index) => {
courseData.splice(index, 1);
setCourseData(courseData);
}
return (
<div className="courses">
<h1>Ongoing Courses</h1>
<div className="row">
{courseData.map((value,index)=>{
return (
<div className="col-md-3">
<Card title={value.title} updateCourseData={updateCourseData} completed={value.completed} content={value.content} value="Resume !" key={index} id={index} />
</div>
);
})}
</div>
</div>
);
}
in the Card.jsx:
<button onClick={() => props.updateCourseData(props.id)} className="btn btn-danger" > {props.value}</button>
function Courses(){
const [coursesData, setCoursesData] = useState(CourseData)
return (
<div className="courses">
<h1>Ongoing Courses</h1>
<div className="row">
{coursesData.map((value,index)=>{
return (
<div className="col-md-3">
<Card coursesData={coursesData} setCoursesData={setCoursesData} title={value.title} completed={value.completed} content={value.content} value="Resume !" key={index} id={index} />
</div>
);
})}
</div>
</div>
);
function Card({id,title,value,content,coursesData,setCoursesData }){
function handleClick(e){
e.preventDefault()
setCoursesData(coursesData => {
const data = coursesData
data.splice(id,1,{
title: title,
completed: value,
content: content,
key: id
})
return data
})
}
return (
<div className="card">
<div className="card-body">
<h2 className="card-title">{title}</h2>
{content}
<br/>
<button onClick={handleClick} className="btn btn-danger">{value}</button>
</div>
</div>
);
Related
so this is my render, it render basically a ui where a username and their email. it also have the option to add new user but when I run the code in my local host, i get this error in my console: Warning: Each child in a list should have a unique "key" prop.
render() {
return (
<div className="App">
{this.state.users.map((user) => {
return (
<React.Fragment>
<div key={user._id} className="box">
<h3>{user.name}</h3>
<h4>{user.email}</h4>
<button
onClick={() => {
this.beginEdit(user);
}}
>
Update
</button>
<button
onClick={() => {
this.deleteUser(user);
}}
>
Delete
</button>
</div>
</React.Fragment>
);
})}
{this.renderAddUser()}
</div>
);
}
}
this is my AddRenderUser
// render new User
renderAddUser() {
return (
<React.Fragment >
<input
type="text"
placeholder="User name"
value={this.state.newUserName}
onChange={this.updateFormField}
name="newUserName"
/>
<input
type="text"
placeholder="User email"
value={this.state.newUserEmail}
onChange={this.updateFormField}
name="newUserEmail"
/>
<button onClick={this.addUser}>Add</button>
</React.Fragment>
);
}
Although I did put the keys props in my div, so not sure how to correct this error
Your key should be in your top-most element
render() {
return (
<div className="App">
{this.state.users.map((user) => {
return (
<React.Fragment key={user._id}>
<div className="box">
<h3>{user.name}</h3>
<h4>{user.email}</h4>
<button
onClick={() => {
this.beginEdit(user);
}}
>
Update
</button>
<button
onClick={() => {
this.deleteUser(user);
}}
>
Delete
</button>
</div>
</React.Fragment>
);
})}
{this.renderAddUser()}
</div>
);
}
}
You need to add the key prop to the React.Fragment tag like this:
<React.Fragment key={user._id}>
Or please try to use index value instead of user.id as follows:
render() {
return (
<div className="App">
{this.state.users.map((user, i) => {
return (
<React.Fragment key={i}>
<div className="box">
<h3>{user.name}</h3>
<h4>{user.email}</h4>
<button
onClick={() => {
this.beginEdit(user);
}}
>
Update
</button>
<button
onClick={() => {
this.deleteUser(user);
}}
>
Delete
</button>
</div>
</React.Fragment>
);
})}
{this.renderAddUser()}
</div>
);
}
function App() {
const [people, setPeople] = useState([
{
name: "Model Baby",
url:"https://www.themodelskit.co.uk/wp-
content/uploads/2021/10/shutterstock_1431963185.jpg"
},
{
name: "Seema Jaswal",
url:"https://static.standard.co.uk/2021/06/14/16/euro_2020_live_seema_jaswal_01-1.jpg?
width=968&auto=webp&quality=50&crop=968%3A645%2Csmart"
},
{
name: 'Plaboi Baby',
url: '../assets/IMG_20210811_105110_849.webp'
}
]);
const [per, setPer] = useState(people.name);
return (
<div className="app">
I am try to update my sidebar from the data above, i am trying to track changes in my sidebar from the main app, how do i effectively deploy useState or context API for this purpose
<Routes>
<Route path='/explore' element={<>
<div className='app__tinder'>
<TinderCards people={people} setPer={setPer} />
<SwipeButtons />
</div>
<aside className='app__sidebar right'>
<RightSidebar per={per} />
</aside>
</div>
</div>
</>} />
</div>
);
}
export default App;
TinderCard.js i need the name and age here to update on the sidebar when it changes
function TinderCards({people, setPer}) {
return (
<div>
<div className='tinderCards__cardContainer'>
{people.map((person) => (
<TinderCard className="swipe" key={person.name} preventSwipe={["up, down"]} onClick=
{() => {setPer(person.name)}} >
<div className='card' style={{ backgroundImage: `url(${person.url})`}}>
<h3>{person.name}</h3>
</div>
</TinderCard>
))}
</div>
</div>
)
}
export default TinderCards
RightSidebar, i tried applying useState but i am not sure that i am using it properly, pls help
function RightSidebar({per}) {
console.log("move", per)
return (
<div className='rightSidebar'>
{/* {people.map((person) => ( */}
<div className='rightSidebar__contents'>
<h1>About</h1>
<Card className='rightSidebar__card'>
<div className='card__nameContents'>
<CardHeader className='card__nameAge' title = {per.name} subheader =
{per.age} avatar =
{<VerifiedIcon className='activeIcon verified' />} />
<CardHeader className='card__active' title = "active" avatar=
{<FiberManualRecordIcon className='activeIcon' />} />
</div>
What I`m doing wrong?It also says: "Check the render method of Card" , which is here:
<div className="grid-container">
{pokemonData.map((pokemon, i) => {
console.log(pokemon.id) // unique numbers are here
return <Card key={pokemon.id} pokemon={pokemon} />
})}
</div>
Card component itself:
function Card({ pokemon }) {
return (
<div className="card">
<div className="card__image">
<img src={pokemon.sprites.front_default} alt="Pokemon" />
</div>
<div className="card__name">
{pokemon.name}
</div>
<div className="card__types">
{
pokemon.types.map(type => {
return (
<div className="card__type" style={{backgroundColor: typeColors[type.type.name]}}>
{type.type.name}
</div>
)
})
}
</div>
<div className="card__info">
<div className="card__data card__data--weight">
<p className="title">Weight:</p>
<p>{pokemon.weight}</p>
</div>
<div className="card__data card__data--height">
<p className="title">Height:</p>
<p>{pokemon.height}</p>
</div>
<div className="card__data card__data--ability">
<p className="title">Abilities:</p>
{/* {console.log(pokemon.abilities)} Temporary for dev puprose */}
{pokemon.abilities.map(ability => <p>{ability.ability.name}</p>
)}
</div>
</div>
</div>
);
}
export default Card;
You can use the index of the array may be your data is having some kind of duplicate. It is recommended that you pass a key prop whenever you are returning a list.
<div className="grid-container">
{pokemonData.map((pokemon, i) => {
console.log(pokemon.id) // unique numbers are here
return <Card key={i} pokemon={pokemon} />
})}
</div>
Equally, check this segment of card components.
{
pokemon.types.map((type,i) => {
return (
<div key={i} className="card__type" style={{backgroundColor:
typeColors[type.type.name]}}>
{type.type.name}
/div>
)
})
}
And
<div className="card__data card__data--ability">
<p className="title">Abilities:</p>
{/* {console.log(pokemon.abilities)} }
{pokemon.abilities.map((ability, i) => <p key={i}>{ability.ability.name}
</p>
)}
</div>
Previous answer will solve your problem. However, for your info, I would also like to add here.
For React a key attribute is like an identity of a node/element/tag which helps React to identify each item in the list and apply reconciliation correctlyon each item. Without a key React will render your component but may cause issue when you re-order your list.
React recommends to use id of the data instead of index number. However, if your list does not re-orders/ sorts or do not have id then you can use index.
You can read more here:
https://reactjs.org/docs/lists-and-keys.html
Change this:
<div className="card__types">
{
pokemon.types.map(type => {
return (
<div className="card__type"
style={{backgroundColor:typeColors[type.type.name]}}
>
{type.type.name}
</div>
)
})
}
</div>
to:
<div className="card__types">
{
pokemon.types.map((type, key) => {
return (
<div key={key} className="card__type"
style={{backgroundColor:typeColors[type.type.name]}}
>
{type.type.name}
</div>
)
})
}
</div>
and:
{pokemon.abilities.map(ability => <p>{ability.ability.name}</p>
to:
{pokemon.abilities.map((ability,key) => <p key={key} >{ability.ability.name}</p>
I'm a bit new to React and I've been having some problems understanding the workarounds of certain methods that I've used in other languages.
The Problem:
What I was hoping to achieve is that whenever the user clicks a button, the app will render a new section displaying some variable values. What I did was that when the user clicked a button, an state changed, and let the new Component render, and I passed the data through its props.
The problem is, If I understand correctly, that I'm passing the old values when I create the component and not the actual/updated values that I want to render...
Let's say I have this following variables.
const user_data = {
pic_url: 'null',
followers: 'Loading...',
followings: 'Loading...',
nTweets: 'Loading...',
};
Those variables are going to change value whenever the user click a button.
This next block of code is what I use to render the next component where I want the new values.
const SomeComponent = props => {
const [resolved, setResolved] = useState({ display: false });
const displayValidation = props => {
setResolved({ ...resolved, display: !resolved.display });
};
function getData(username) {
const url = 'https://www.twitter.com/' + username;
getHTML(url)
.then(res => {
getUserData(res).then(res => {
user_data.followers = res.followers;
user_data.followings = res.followings;
user_data.nTweets = res.nTweets;
user_data.pic_url = res.pic_url;
console.log('Updated data:', user_data);
displayValidation();
});
})
.catch(function(error) {
console.error('Username was not found.');
});
}
const handleSubmit = event => {
event.preventDefault();
console.log('Resolving data...');
getData(user.username);
};
return (
<React.Fragment>
<Navbar />
<div className="container lg-padding">
<div className="row" id="getTracker">
<div className="col-sm-12 center">
<div className="card text-center hoverable">
<div className="card-body">
<div className="input-field">
<i className="material-icons prefix">account_circle</i>
<input
id="username"
type="text"
className="validate"
value={user.username}
onChange={handleChange}
/>
<label htmlFor="username">Enter a username to track</label>
</div>
<input
type="button"
onClick={handleSubmit}
value="Track"
className="btn-large blue darken-4 waves-effect waves-light"
/>
</div>
</div>
</div>
</div>
<div className="row">
<div className="col-sm-12">
**{resolved.display && <DisplayData type={1} data={user_data} />}**
</div>
</div>
</div>
<Footer />
</React.Fragment>
);
};
I want to see the new values, but it always render the first values that I passed when creating the component.
This is the component that I create
import React from 'react';
const DisplayData = props => {
const user = props.data;
console.log('Display', user);
switch (props.type) {
case 1: //Twitter
return (
<React.Fragment>
<div className="row lg-padding">
<div className="col-sm-12 lg-padding center">
<img
src={user.pic_url}
alt="profile_picture"
style={{ width: 50 + '%' }}
/>
</div>
<h2>{user.username}</h2>
</div>
<div className="row lg-padding">
<div className="col-sm-4">
<h4>Tweets: {user.nTweets}</h4>
</div>
<div className="col-sm-4">
<h4>Followers: {user.followers}</h4>
</div>
<div className="col-sm-4">
<h4>Followings: {user.followings}</h4>
</div>
</div>
</React.Fragment>
);
case 2: //Instagram
return <React.Fragment />;
default:
return (
<React.Fragment>
<div className="row lg-padding">
<div className="col-sm-12 lg-padding center">
<img
src={user.pic_url}
alt="profile_picture"
style={{ width: 50 + '%' }}
/>
<h2>Instagram_User</h2>
<h4>Posts: ND</h4>
<h4>Followers: ND</h4>
<h4>Followings: ND</h4>
</div>
</div>
</React.Fragment>
);
}
};
export default DisplayData;
How can I update the data in the component or render the component when the data is updated?
Maybe your user_data might to be a state object.
// Somecomponent ...
const [user_data, setUser_data] = useState({
pic_url: 'null',
followers: 'Loading...',
followings: 'Loading...',
nTweets: 'Loading...'
})
/* Rest of stuff */
const handleSubmit = async event => {
/*...*/
const userData = await getData(user.username)
setUser_data(userData)
}
// Then display the stated-stored user_data
<div className="col-sm-12">
**{resolved.display && <DisplayData type={1} data={user_data} />}**
</div>
I have a React component which list items from the Item component.
Below you can see how it looks.
const ListHolder = () => (
<div>
<div className="panel">
<div className="panel-heading">
<h3 className="panel-title">List Title</h3>
</div>
<div className="panel-body">
<Item
title="A Title"
desc="Desc 1."
/>
<Item
title="Another Title"
desc="Desc 2."
/>
<Item
title="Some of title"
desc="Desc 3."
/>
</div>
</div>
</div>
);
export default ListHolder;
Item components are currently hardcoded.
How can I populate / insert the data from some Json data?
If you pass your items data as props of your component, you could do something like:
const ListHolder = ({items}) => (
<div>
<div className="panel">
<div className="panel-heading">
<h3 className="panel-title">List Title</h3>
</div>
<div className="panel-body">
{ items.map((item) => <Item title={item.title} desc={item.desc} />)}
</div>
</div>
</div>
);
~ EDIT after first comment ~
That is if you can use so called
Otherwise the "usual" way can look something like:
class ListHolder extends React.Component {
render() {
const items = [{ "title": "title", "desc": "some desc" }, { "title": "title2", "desc": "some other desc" }];
return (
<div>
<div className="panel">
<div className="panel-heading">
<h3 className="panel-title">List Title</h3>
</div>
<div className="panel-body">
{ items.map((item) => <Item title={item.title} desc={item.desc} /> )}
</div>
</div>
</div>
);
}
}