[英]How to access the input value of children component from parents component in ReactJs?
我对输入值的访问有问题,我在这里使用的是.map() 。 这是代码, <QuestionLabel/>
是子组件。 projectsData.projectDetail
是可用数据
//..
{projectsData.projectDetail.questions.map((question) => (
<QuestionLabel
questionTitle={question}
/>
))}
//child component
const QuestionLabel=(props)=>{
const [answerInput, setAnswerInput] = React.useState("");
return(
<div className="contact">
<form className="contact-form" autocomplete="off">
<div class="contact-form-group">
<label
for="name"
class="contact-form-label"
>
{props.questionTitle}
</label>
<input
id="name"
type="text"
class="contact-form-input"
value={answerInput}
onChange={(answer) => setAnswerInput(answer.target.value)}
/>
</div>
</form>
</div>
);
}
export default QuestionLabel;
有很多方法可以从父组件的子组件获取值。 您可以调用从父级到子级的函数,以在parent state
发生更改时为其设置value
。 例子:
const ParentComponent =(props)=>{
const [valueFromChild, setValueFromChild] = useState('');
return <>
{valueFromChild}
<QuestionLabel questionTitle={'Title'} setValueFromChild={setValueFromChild}/>
</>
}
const QuestionLabel=(props)=>{
const [answerInput, setAnswerInput] = React.useState("")
useEffect(() => {
props.setValueFromChild(answerInput);
}, [answerInput]);
return(
<div className="contact">
<form className="contact-form" autoComplete="off">
<div class="contact-form-group">
<label
for="name"
class="contact-form-label"
>
{props.questionTitle}
</label>
<input
id="name"
type="text"
class="contact-form-input"
value={answerInput}
onChange={(answer) => setAnswerInput(answer.target.value)}
/>
</div>
</form>
</div>
);
}
所以你需要在父级中设置输入状态。
由于您正在通过问题数组进行映射以呈现QuestionLabel
我们可以试试这个...
//..
const ParentComponent = () => {
const [answers, setAnswers] = React.useState({})
useEffect(() => {
projectsData.projectDetail.questions.forEach((_, i) => {
setAnswers(previousAnswers => {...previousAnswers, ["name" + i]: ""})
})
}, [])
const handleAnswers = (e) => {
setAnswers(previousAnswers => {...previousAnswers, [e.target.name]: [e.target.value]})
}
//..
然后
//..
{
projectsData.projectDetail.questions.map((question, i) => {
return (
<QuestionLabel questionTitle={question} inputName={"name" + i} answers={answers} handleAnswers={handleAnswers} />
)
})
}
最后...
//child component
const QuestionLabel=(props)=>{
return(
<div className="contact">
<form className="contact-form" autocomplete="off">
<div class="contact-form-group">
<label
for={props.inputName}
class="contact-form-label"
>
{props.questionTitle}
</label>
<input
id={props.inputName}
name={props.inputName}
type="text"
class="contact-form-input"
value={answers[props.inputName]}
onChange={handleAnswers}
/>
</div>
</form>
</div>
);
}
export default QuestionLabel;
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