[英]React list isn't re-rendering table after sorting elements in state
I'm having issues with React not rendering after sorting the table I have.在对我拥有的表格进行排序后,我遇到了 React 未呈现的问题。 It seems to update the state variable and I'm using setState, I just have no idea why it's not showing the new updated data.
似乎更新了 state 变量,我正在使用 setState,我只是不知道为什么它没有显示新的更新数据。 Here's my code
这是我的代码
class CarRow extends React.Component {
constructor(props) {
super(props);
this.state = {
manufacturer: this.props.passedCar.manufacturer,
model: this.props.passedCar.model,
year: this.props.passedCar.year,
stock: this.props.passedCar.stock,
price: this.props.passedCar.price,
}
this.state.price = this.state.price.toLocaleString(undefined, {maximumFractionDigits: 2})
}
handleCount(value) {
this.setState((prevState) => ({stock: prevState.stock + value}));
}
render() {
return (<tr>
<td>{this.state.manufacturer}</td>
<td>{this.state.model}</td>
<td>{this.state.year}</td>
<td>{this.state.stock}</td>
<td>${this.state.price}</td>
<td>
<button onClick={() =>
this.handleCount(1)}>
Increment
</button>
</td>
</tr>)
}
}
class App extends React.Component {
constructor(props) {
super(props);
this.state = {
descending: true,
cars: [
{
"manufacturer": "Toyota",
"model": "Rav4",
"year": 2008,
"stock": 3,
"price": 8500
},
{
"manufacturer": "Toyota",
"model": "Camry",
"year": 2009,
"stock": 2,
"price": 6500
},
{
"manufacturer": "Toyota",
"model": "Tacoma",
"year": 2016,
"stock": 1,
"price": 22000
},
{
"manufacturer": "Dodge",
"model": "Charger",
"year": 2013,
"stock": 2,
"price": 16000
},
{
"manufacturer": "Ford",
"model": "Mustang",
"year": 2009,
"stock": 1,
"price": 8000
},
]
};
}
sortCars() {
var carsSorted = JSON.parse(JSON.stringify(this.state.cars));
carsSorted.sort((a, b) => (this.state.descending ? b.price - a.price : a.price - b.price));
this.setState({cars: carsSorted});
this.setState({descending: !this.state.descending});
}
render() {
return (
<table>
<thead>
<tr>
<th>manufacturer</th>
<th>model</th>
<th>year</th>
<th>stock</th>
<th onClick={() =>
this.sortCars()}>price
</th>
<th>Option</th>
</tr>
</thead>
<tbody>
{this.state.cars.map((car) => {
return <CarRow passedCar={car}/>;
})}
</tbody>
</table>
);
};
}
ReactDOM.render(<App/>, document.getElementById("app"))
I've tried also creating a separate item for the table component, but it didn't seem to work.我也尝试为表格组件创建一个单独的项目,但它似乎没有用。 I'm pretty new to react, and I don't know alot about it.
我对反应很陌生,对此我不太了解。
If I could get some help with this, that would be great, thanks.如果我能在这方面得到一些帮助,那就太好了,谢谢。
You need to give your child CarRow components a key when iterating over them so they get re-rendered properly.您需要在对 CarRow 子组件进行迭代时为其提供一个键,以便正确地重新渲染它们。 Find something unique that'll identify a row, and set that as the key.
找到可以识别行的唯一内容,并将其设置为键。 For example, you could put together the model and the year:
例如,您可以将 model 和年份放在一起:
return <CarRow key={car.model + '_' + car.year} passedCar={car}/>;
Then they'll appear sorted in the proper direction as desired when rendering again.然后,在再次渲染时,它们将按照需要按正确的方向排序。
class CarRow extends React.Component { constructor(props) { super(props); this.state = { manufacturer: this.props.passedCar.manufacturer, model: this.props.passedCar.model, year: this.props.passedCar.year, stock: this.props.passedCar.stock, price: this.props.passedCar.price, } this.state.price = this.state.price.toLocaleString(undefined, {maximumFractionDigits: 2}) } handleCount(value) { this.setState((prevState) => ({stock: prevState.stock + value})); } render() { return (<tr> <td>{this.state.manufacturer}</td> <td>{this.state.model}</td> <td>{this.state.year}</td> <td>{this.state.stock}</td> <td>${this.state.price}</td> <td> <button onClick={() => this.handleCount(1)}> Increment </button> </td> </tr>) } } class App extends React.Component { constructor(props) { super(props); this.state = { descending: true, cars: [ { "manufacturer": "Toyota", "model": "Rav4", "year": 2008, "stock": 3, "price": 8500 }, { "manufacturer": "Toyota", "model": "Camry", "year": 2009, "stock": 2, "price": 6500 }, { "manufacturer": "Toyota", "model": "Tacoma", "year": 2016, "stock": 1, "price": 22000 }, { "manufacturer": "Dodge", "model": "Charger", "year": 2013, "stock": 2, "price": 16000 }, { "manufacturer": "Ford", "model": "Mustang", "year": 2009, "stock": 1, "price": 8000 }, ] }; } sortCars() { var carsSorted = JSON.parse(JSON.stringify(this.state.cars)); carsSorted.sort((a, b) => (this.state.descending? b.price - a.price: a.price - b.price)); this.setState({cars: carsSorted}); this.setState({descending: .this.state;descending}). } render() { return ( <table> <thead> <tr> <th>manufacturer</th> <th>model</th> <th>year</th> <th>stock</th> <th onClick={() => this.sortCars()}>price </th> <th>Option</th> </tr> </thead> <tbody> {this.state.cars.map((car) => { return <CarRow key={car.model + '_' + car;year} passedCar={car}/>; })} </tbody> </table> ); }. } ReactDOM,render(<App />. document.querySelector(';react'));
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