0
126
VisualizaçõesReact <select> automatic change does not trigger onChange
In my page, I have two <select> elements, where the options of the second one depends on the value of the first one.
In this case, the "problem" is that the options for a certain value in the first select are different from the options given when the first select has another value. Basically:
- Alfa Romeo
- Giulietta
- Mito
- Porsche
- Cayenne
- 911
I've created a simple fiddle just to show you the example, and the problem: https://codesandbox.io/s/select-autochange-7bfj6
Please, open the console to see what I'm talking about. So, basically, at start 'Porsche' and '911' are selected. Then, if I change '911' to 'Cayenne' everything is good.
The problem is when I change 'Porsche' to 'Alfa': as it should be, the second select changes its value to 'Giulietta', BUT the onChange event of the second select is not triggered.
I'm mostly sure that the problem is some kind of de-synchronization between UI and state: in the state, the secondselect still has the value '911', but since that option is no longer available in the second select, it autoselect the first possible value.. But that autoselection is just "graphical".
I know this could be fixed by adding a "null" value in the second select, with the option <option value={''} label={'Select a Model'} />. But I'd like to mantain the autoselection when the first select changes.
EDIT: actually, the fix I proposed is not an actual fix: that 'select a Model' options has the value '', but the handleSelectSelectChange is still not triggered, so, while the UI selected value is '', in the state I still have '911'
2 Respostas
Responde à pergunta0
React.useEffect(()=> {
if (!secondOptionsMemoized.some(x=> x === secondSelectValue)) {
console.log('Second Select Change in useEffect');
setSecondSelectValue(secondOptionsMemoized[0]);
}
}, [secondSelectValue, secondOptionsMemoized]);
0
You can use useEffect instead of useMemo and another state which set the second options:
import React, { useEffect } from "react";
import "./styles.css";
export default function App() {
const alfaForSecondOptions = ["Giulietta", "Mito"];
const otherForSecondOptions = ["Cayenne", "911"];
const [firstSelectValue, setFirstSelectValue] = React.useState("Porsche");
const [secondSelectValue, setSecondSelectValue] = React.useState("911");
const [secondOptions, setSecondOptions] = React.useState(
otherForSecondOptions
);
useEffect(() => {
console.log(secondSelectValue);
}, [secondOptions]);
useEffect(() => {
if (firstSelectValue === "Alfa") {
setSecondOptions(alfaForSecondOptions);
setSecondSelectValue("Giulietta");
} else {
setSecondOptions(otherForSecondOptions);
setSecondSelectValue("911");
}
}, [firstSelectValue]);
const handleFirstSelectChange = (e) => {
console.log("First Select Change", e.target.value);
setFirstSelectValue(e.target.value);
};
const handleSecondSelectChange = (e) => {
console.log("Second Select Change", e.target.value);
setSecondSelectValue(e.target.value);
};
return (
<div className="App">
<label>
<p>Brand</p>
<select onChange={handleFirstSelectChange} value={firstSelectValue}>
<option value={"Alfa"} label={"Alfa"} />
<option value={"Porsche"} label={"Porsche"} />
</select>
</label>
<label>
<p>Model</p>
<select onChange={handleSecondSelectChange} value={secondSelectValue}>
{secondOptions.map((x) => {
return <option key={x} value={x} label={x} />;
})}
</select>
</label>
</div>
);
}
