How to render element depends on selected option? - django

Question

i'm newbie in react js , and i want to have a form with select options
i want that when user click on each option , each option render different elements
class Resepy extends Component {
state = {
Resepy : 'default'
}
render() {
return = (
<div className="Resepy">
<form>
<select id="id_field1" name="field1" onChange={(e) => this.state.Resepy = "Burger"}>
<option value="default">Food type not selected</option>
<option value="burger" onClick={(e) => this.setState({ Resepy: 'Burger' })}>Burger</option>
<option value="pizza" onClick={(e) => this.setState({ Resepy: 'Pizza' })}>Pizza</option>
</select>
<div className="food">
{ this.state.Resepy === "burger" ? <div className="burger"></div> //can return any html
: <div className="default">default</div>
}
<div className="pizza"></div>
<div className="food-detail"></div>
</div>
<button type="submit">Add to tray</button>
</form>
</div>
);
}
}
export default Resepy;

Answer 1

General ternary operator used for more readable code.
Like this:
<form>//can be any element
{ codition == true ? <div>It is true</div> //can return any html
: <div>It is false</div>
}
</form>
Tested, working. Problem was with onClick method option cannot invoke that event.
class Resepy extends React.Component {
constructor(props){
super(props);
this.state = {
selected : 'default'
};
}
setSelected = (event) => {
let select = document.getElementById("id_field1");
this.setState({selected: select.value});
//document.getElementById("test").innerHTML = select.value;
}
render() {
return (
<div className="Resepy">
<h1>Something</h1>
<form>
<select id="id_field1" name="field1" onChange={this.setSelected}>
<option value="default">Food type not selected</option>
<option value="burger">Burger</option>
<option value="pizza">Pizza</option>
</select>
<div id="test"></div>
<div className="food">{
(this.state.selected === "default") ?
<div className="default">Default</div>
: (this.state.selected === "burger") ?
<div className="burger">Burger</div>
: <div className="pizza">Pizza</div>
}</div>
<button type="submit">Add to tray</button>
</form>
</div>
);
}
}

Answer 2

I have a hard time understanding you, but the most likely thing you could be trying to achieve with the following code from your original question:
<div className="burger" Resepy={this.state.Resepy === 'burger'}></div>
is:
<div className="food">
<div className={this.state.Resepy} />
</div>
Working example (but I am using Hooks instead of a class component):
const App = () => {
const [selected, setSelected] = React.useState('default')
const handleChange = (event) => {
setSelected(event.target.value)
}
return (
<div>
<select value={selected} onChange={handleChange}>
<option>default</option>
<option>burger</option>
<option>pizza</option>
</select>
<div className="food">
<div className={selected}>{selected}</div>
</div>
</div>
)
}
ReactDOM.render(<App />, document.getElementById('root'))
.default { color: gray; }
.burger { color: orange; }
.pizza { color: red; }
<script crossorigin src="https://unpkg.com/react#16/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom#16/umd/react-dom.development.js"></script>
<div id="root"></div>

Answer 3

Now i want to render html elements depends on values , i tried this but it shows just [Object Object]
setSelected = (event) => {
let select = document.getElementById("id_field1");
document.getElementById("food").innerHTML =
select.value == "default" ?
<div className="default">Default</div>
: select.value == "Burger" ?
<div className="burger">Burger</div>
: <div className="pizza">Pizza</div>
}