I'm trying to send list of selected radio button ids from multiple radio button groups on clicking send button,
My problem: I am getting selected radio button from backend , then I should be able to change the radio button and send back to backend. but when I try to change the radio button it is not working.
What I did not understand: How to handle the on change function, normally on change we can change the state but to change the state on load we should grab the values radio buttons. Finally I got struck here, not understanding how to move forward.
Here is the wireframe and code snippet:
function CardsList(props) {
const cards = props.cards;
return (
<div>
{cards.map((card, idx) => (
<div>
{card.cardName}
{
card.options.map((lo,idx) => (
<li key={idx}>
<input
className="default"
type="radio"
name={card.cardName}
checked={lo.selected}
/>))
}
<div>
))}
</div>
);
}
//array of cards coming from the backend
const cards = [
{cardName:'card1',options:[{radioName:'card1-radio1',selected:'true'},
{radioName:'card1-radio2',selected:'false'}]},
{cardName:'card2',options:[{radioName:'card2-radio1',selected:'true'},
{radioName:'card2-radio2',selected:'false'}]}
];
ReactDOM.render(
<CardsList cards={cards} />,
document.getElementById('root')
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id="root"></div>
You should have this in your browser: We have five radio buttons each one has a string value captured by the handleChange function when clicked. The string value needs to be changed to a number by adding the '+' sign in front of the e like so setIsRadio(+e. currentTarget. value);
Only one radio button in a group can be selected at the same time.
Using a Radio Button Group with a FormSet up a form with a radio button group like this. As you can see in the above example, in the form there are three different radio buttons along with the submit button, and each radio button is attached with one onChange function, called onValueChange() .
Radio buttons allow a user to select a single option among multiple options. You can set the Choice Value of each option, for each button, as well as group these buttons by giving them the same Group Name.
You can use an object as a lookup table that holds the group names as keys.
On each change you will need to find the relevant group with the relevant option and set the new state accordingly.
Important! - one thing to notice here, is that i changed the type of the selected
property from a String
to a Boolean
. this will let me handle the conditions like this:
<input checked={option.selected} />
If you can't change it to a Boolean
then you will need to handle the condition like this:
<input checked={option.selected === 'true'} />
Here is a running example:
//array of cards coming from the backend
const data = [
{
cardName: 'card1', options: [{ radioName: 'card1-radio1', selected: true },
{ radioName: 'card1-radio2', selected: false }]
},
{
cardName: 'card2', options: [{ radioName: 'card2-radio1', selected: true },
{ radioName: 'card2-radio2', selected: false }]
}
];
class CardsList extends React.Component {
constructor(props) {
super(props);
this.state = {
cards: []
};
}
componentDidMount() {
setTimeout(() => {
// mimic an async server call
this.setState({ cards: data });
}, 1000);
}
onInputChange = ({ target }) => {
const { cards } = this.state;
const nexState = cards.map(card => {
if (card.cardName !== target.name) return card;
return {
...card,
options: card.options.map(opt => {
const checked = opt.radioName === target.value;
return {
...opt,
selected: checked
}
})
}
});
this.setState({ cards: nexState })
}
onSubmit = () => { console.log(this.state.cards) };
render() {
const { cards } = this.state;
return (
<div>
{
cards.length < 1 ? "Loading..." :
<div>
{cards.map((card, idx) => (
<ul>
{card.cardName}
{
card.options.map((lo, idx) => {
return <input
key={idx}
type="radio"
name={card.cardName}
value={lo.radioName}
checked={!!lo.selected}
onChange={this.onInputChange}
/>
})
}
</ul>
))
}
< button onClick={this.onSubmit}>Print Cards</button>
</div>
}
</div>
);
}
}
ReactDOM.render(<CardsList />, document.getElementById('root'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id="root"></div>
The reason why you can't change them is because of their current checked state which you are setting here:
<input
className="default"
type="radio"
name={card.cardName}
checked={lo.selected}
/>
An approach I have used for this exact scenario is storing the component's state (from the server) in my component's state (this.state
), passing the state to the element: checked={this.state.isChecked}
, and updating the element's state onClick
.
Example:
class CardsList extends Component {
constructor(props){
super(props);
this.state = {isChecked: false};
this.inputOnClick = this.inputOnClick.bind(this);
}
//fetch data from server
fetchData(){
fetch('/api')
.then(res => res.json())
//this will be our initial state
.then(res => this.setState(res))
}
componentDidMount(){
this.fetchData();
}
//change radio button state on click
inputOnClick(e){
e.preventDefault();
//invert state value
this.setState((prevState, props) => {isChecked: !prevState.isChecked});
}
render(){
return (
<input
type="radio"
checked={this.state.isChecked}
onClick={this.inputOnClick}
/>
)
}
}
this answer may work with single radio button group , but i am facing problem with multiple radio buttons with in multiple radio button groups.if you see the array of cards , how does it know which radio button group it belongs to.
We can modify the state based on the radio button's name.
Let's save all of your cards in your component's state. I know the cards are retrieved from the server and will be saved using setState
but I am writing it like this for visual purposes.
this.state = {cards: [
{ cardName:'card1',
options:[
{radioName:'card1-radio1',selected:true},
{radioName:'card1-radio2',selected:false}
]
},
{ cardName:'card2',
options:[
{radioName:'card2-radio1',selected:true},
{radioName:'card2-radio2',selected:false}
]
}
]}
Now when we click on a radio button, we will use that radio button's name to update the state where it needs to be updated. Since React state needs to be immutable, we will create a deep copy of the state, modify it, and then set the state with it.
inputOnClick(e){
e.preventDefault();
var thisRadioBtn = e.target.name;
//make a deep copy of the state
const stateCopy = JSON.parse(JSON.stringify(this.state.cards));
//go through state copy and update it
stateCopy.forEach(card => {
card.options.forEach(option => {
if(option.radioName === thisRadioBtn){
//invert value
//make sure the values are booleans
option.selected = !option.selected;
}
});
});
//update the components state
this.setState({cards: stateCopy});
}
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