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[英]Why am I getting 'TypeError: Cannot read property 'props' of undefined' (react-router, React-Redux)?
[英]How to print props object in JSX, i am getting TypeError: Cannot read property of undefined
我試圖在JSX中打印props的值,即使當我嘗試打印單個對象時日志顯示該對象,它也會引發錯誤TypeError:無法讀取未定義的屬性<'objects'>
我正在使用REDUX,我嘗試使用map,forEach等進行循環。仍然出現錯誤。 console.log(“ props.stories”)顯示對象,但是當我嘗試記錄單個對象時,“ props.stories”變為“未定義”
import React from 'react'
import {connect} from 'react-redux'
import {Link} from 'react-router-dom'
const ShowStory = (props) => {
console.log(props.stories) // shows objects
console.log(props.stories._id) // gives error and above log becomes undefined
return(
<div>
<h1>{props.stories.bookTitle}</h1>
</div>
)
}
const mapStateToProps = (state, props) => {
const id = props.match.params.id
var arr1d = [].concat(...state.stories)
return {
stories: arr1d.find(story => story._id == id),
}
}
export default connect(mapStateToProps)(ShowStory)
如果stories
是一個對象數組,則需要使用.map
函數來訪問它。
刪除此行以擺脫控制台錯誤:
console.log(props.stories._id) // gives error and above log becomes undefined
如果要打印所有故事的書名,請:
<ul>
{props.stories.map((story, index) => (
<li key={index}>{story.bookTitle}</li>
))}
</ul>
如果要打印第一個故事的書的標題,請:
<div>
<h1>{props.stories[0].bookTitle}</h1>
</div>
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