[英]How to use setState with nested JSON array object
我正在嘗試從 MongoDb 獲取數據,但 setState 沒有更新bookInstances
如何使用 setState 更新 bookInstances? 每個數組基本上就像 {"id": ...}
export default class BookInstances extends Component {
constructor(props) {
super(props)
this.BookInstance = this.BookInstance.bind(this);
this.BookInstances = this.BookInstances.bind(this);
this.state = {
bookInstances: []
}
}
componentDidUpdate() {
axios.get('http://localhost:3001/catalog/bookinstances')
.then(res => {
this.setState({ bookInstances: res.data });
})
}
BookInstance(props) {
return <li>{props.bookInstance}</li>
}
BookInstances() {
const bookInstances = this.state.bookInstances;
if (bookInstances) {
return bookInstances.map(bookInstance => {
return <this.BookInstance key={bookInstance} bookInstance={bookInstance.id} />
})
}
}
render() {
return (
<div>
<h1>Book Instance List</h1>
<ul><this.BookInstances /></ul>
</div>
)
}
}
感謝任何幫助?
不知道你現在為什么要使用類組件。盡管如此,你在錯誤的生命周期方法中設置了狀態。
您需要在componentDidMount()
中獲取
componentDidMount() {
axios.get('http://localhost:3001/catalog/bookinstances')
.then(res => {
this.setState({ bookInstances: res.data });
})
}
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