[英]setState of parent does not fire componentWillReceiveProps of child
[英]componentWillReceiveProps in child doesn't receive new props when setState() in parent
我在React中有一個名為“App”的父組件,它使用HighCharts實現呈現“Calories”子組件。
我期望的是根據React生命周期,父渲染子組件然后將調用componentDidMount()。 然后我使用fetch來獲取數據異步,一旦完成它就使用了用戶對象的setState。 然后它將使用user = {this.state.user}重新呈現子組件,並且它將在子組件中可用。 但是當我在子的componentWillReceiveProps中記錄this.props時,用戶對象不存在。 所以子組件中的這一行記錄為“未定義”:
componentWillReceiveProps: function(){
const series = this.props.series;
console.log("component Will Receive Props")
console.log(this.props);
}
這是我的完整代碼:
const App = React.createClass({
//parent component to render all elements and hold state
getInitialState(){
return{
user: {},
series: [{
name: 'Jane',
data: [1, 0, 4]
}, {
name: 'John',
data: [5, 7, 3]
}]
};
},
componentDidMount: function(){
const fb_id = location.pathname.replace("/users/","");
fetch("https://someurl.com/usersdata/" + fb_id)
.then(rsp => rsp.json())
.then(json => {
if(json.error && json.error.message){
throw new Error(json.error.message);
}
this.setState({user:json}, ()=>{
console.log("state updated");
console.log(this.state);
});
});
},
render: function(){
return (
<div className="container">
<div clasNames="row">
<div className="col-xs-12">
{/*Send this.state.user data from fetch to child component*/}
<Calories series={this.state.series} user={this.state.user}/>
</div>
</div>
<div className="row">
<div className="col-xs-7">
<div className="bottom-left" id="weight-line-chart">
<Weight/>
</div>
</div>
<div className="col-xs-5">
<div className="bottom-right" id="avg-calories-pie-chart">
<AverageCal/>
</div>
</div>
</div>
</div>
);
}
});
//Calories Line chart
const Calories = React.createClass({
componentDidMount: function(){
const series = this.props.series;
console.log("component Did Mount");
console.log(this.props);
$(function () {
const myChart = Highcharts.chart('calories-line-chart', {
chart: {
type: 'line'
},
title: {
text: 'Your Calories Over Time'
},
xAxis: {
categories: ['Apples', 'Bananas', 'Oranges']
},
yAxis: {
title: {
text: 'Fruit eaten'
}
},
series: series
});
});
},
componentWillReceiveProps: function(){
const series = this.props.series;
console.log("component Will Receive Props")
console.log(this.props);
$(function () {
const myChart = Highcharts.chart('calories-line-chart', {
chart: {
type: 'line'
},
title: {
text: 'Your Calories Over Time'
},
xAxis: {
categories: ['Apples', 'Bananas', 'Oranges']
},
yAxis: {
title: {
text: 'Fruit eaten'
}
},
series: series
});
});
},
render:function(){
return(
<div>
<h3>Calories Intake</h3>
<div className="top" id="calories-line-chart">
</div>
</div>
);
}
});
任何人都可以幫助我,我做錯了什么?
componentWillReceiveProps
被調用時props
子(父組件內)的值將得到更新,您需要接受新的值作為該參數lifecycle
方法,就像這樣:
componentWillReceiveProps: function(newProps){ //here
console.log("component Will Receive Props", newProps); //it will log the new values
...
}
this.props
內componentWillReceiveProps
將有之前的值,它會在這之后得到更新lifecycle
方法。 如果在render
執行console.log(this.props)
,您將看到更新的值。
為什么我們需要接收新值作為參數?
我認為原因是(不確定),每當我們在父組件中執行setState
時都會調用此方法,無論是否與子組件相關,因此我們需要在對子進行任何任務之前設置一些邏輯(新的道具和舊道具是否相同),因為this.props
將在此方法中具有舊值。
有關componentWillReceiveProps
更多詳細信息,請查看DOC 。
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