在控制台中编译后,我收到以下错误
未捕获的TypeError:无法读取未定义的属性'setState'
这是我的代码,请你帮我找错?我想在x上保存childData.pic的数据然后我读了它我试过this.x,this.state.x,x ...并且每次我得到相同的错误
import React, { Component } from 'react'
import * as firebase from 'firebase'
import './scss/style.scss';
import QuickView from './QuickView';
export default class Dashboard extends Component {
constructor() {
super();
this.state = {
speed: '', snapshot: undefined, x: ''
}
}
componentDidMount() {
var w = firebase.auth().currentUser
var rootRef = firebase.database().ref(`restaus/`).orderByKey();
rootRef.once("value")
.then(function (snapshot) {
snapshot.forEach(function (childSnapshot) {
var key = childSnapshot.key;
var childData = childSnapshot.val();
var x;
this.setState({
x: childData.pic,
})
});
});
this.setState({
email: w.email,
})
}
render() {
return (
<div>
<h4>your email is {this.state.email}</h4>
<div className="product">
<div className="product-image">
<img src={this.x} /*onClick={this.quickView.bind(this, name)}*/ />
</div>
<h4 className="product-name">{this.state.x}</h4>
<p className="product-price">{this.props.x}</p>
<div className="product-action">
<button type="button" >Add To cart</button>
</div>
</div>
</div>)
}
}
1 回答
请正确格式化您的代码,人们很难关注 . 问题是你使用
function(snapshot)
,在这种情况下this
没有指向你的Component,它指向调用它的函数 .您可以使用箭头功能来解决此问题https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions
例如: