[英]How could i pass a value from a child component to parent, when i have multiple child components?
I creat multiple components, they have the same hierarchy, and inside they i also call other component call, now i want to create functions on my which will update the values i'm passing as props to my component.我创建了多个组件,它们具有相同的层次结构,并且在它们内部我还调用了其他组件调用,现在我想在我的组件上创建函数,它将更新我作为道具传递给组件的值。 I manage to pass the functions as props, but can't manage to pass the value from child as parameters to the functions, so i could update only the props especific to that child.我设法将函数作为道具传递,但无法将孩子的值作为参数传递给函数,因此我只能更新特定于该孩子的道具。
App应用程序
function App() {
// eslint-disable-next-line
const [content, setContent] = useState(images)
const [count, setCount] = useState(content.votes)
console.log(count)
const upVote = (id) => {
alert('up =>', id)
}
const downVote = () => {
alert('down')
}
return (
<div className="App">
<div className="grid">
{content.map((picture, index) => {
return <Card key={index} picture={picture} teste={[upVote, downVote]}/>
})
}
</div>
</div>
)
}
Card卡片
function Card({ picture, teste }) {
return (
<div className="card">
<div className="container">
<img
width="300"
alt={`id: ${picture.id}`}
src={picture.src}
className="image"
/>
<Options votes={0} originalPost={picture.original_post} teste={teste[0]}/>
</div>
</div>
)
}
Options选项
function Options({ votes, originalPost, teste }) {
const [count, setCount] = useState(votes)
const [styling, setStyling] = useState('#696969')
function countStyle(count) {
if (count > 0){
setStyling('#008000')
} else if (count < 0) {
setStyling('#B22222')
} else {
setStyling('#696969')
}
}
return (
<div>
<button onClick={() => teste(count)} className="buttons">teste</button>
<button title="Down vote" onClick={() => {
setCount(count - 1)
countStyle(count-1)
// style(count - 1)
}} className="buttons">-</button>
<span title="Vote counter" style={{color: styling}} className="counter">{count}</span>
<button title="Up vote" onClick={() => {
setCount(count + 1)
// style(count + 1)
countStyle(count +1)
}} className="buttons">+</button><br></br>
<a href={originalPost}
target="_blank"
title="Click to check the original post"
rel="noopener noreferrer"
className="link">Original post</a>
</div>
)
}
I would start by consolidating your state into the App component.我首先将您的 state 合并到 App 组件中。 Save the votes on your content array on each picture object.将投票保存在每张图片 object 上的内容数组上。 Pass the upvote and downvote functions down to each children and call them from your button clicks.将 upvote 和 downvote 功能传递给每个孩子,并通过您的按钮点击调用他们。 I would also calculate the styling based on the props, rather than use state.我还会根据道具计算样式,而不是使用 state。
App应用程序
function App() {
let initialstate = images.map(image => {
image.votes = 0;
return image;
});
const [content, setContent] = useState(initialstate);
const upVote = index => {
setContent(content[index].votes + 1);
};
const downVote = index => {
setContent(content[index].votes - 1);
};
return (
<div className="App">
<div className="grid">
{content.map((picture, index) => {
return <Card key={index} picture={picture} index={index} upVote={upVote} downVote={downVote} />;
})}
</div>
</div>
);
}
Card卡片
function Card({ index, picture, ...props }) {
const upVote = () => props.upVote(index);
const downVote = () => props.downVote(index);
return (
<div className="card">
<div className="container">
<img
width="300"
alt={`id: ${picture.id}`}
src={picture.src}
className="image"
/>
<Options votes={picture.votes} originalPost={picture.original_post} upVote={upVote} downVote={downVote}/>
</div>
</div>
)
Options选项
function Options({ votes, originalPost, upVote, downVote }) {
let styling = '#696969';
if (count > 0) {
styling = '#008000';
} else if (count < 0) {
styling = '#B22222';
} else {
styling = '#696969';
}
return (
<div>
<button title="Down vote" onClick={downVote} className="buttons">
-
</button>
<span title="Vote counter" style={{ color: styling }} className="counter">
{votes}
</span>
<button title="Up vote" onClick={upVote} className="buttons">
+
</button>
<br></br>
<a
href={originalPost}
target="_blank"
title="Click to check the original post"
rel="noopener noreferrer"
className="link"
>
Original post
</a>
</div>
);
}
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