Javascript Reactjs 异步渲染组件

Reactjs async rendering of components

提问by tuna

I want to render my component after my ajax request is done.

我想在我的 ajax 请求完成后呈现我的组件。

Below you can see my code

下面你可以看到我的代码

var CategoriesSetup = React.createClass({

    render: function(){
        var rows = [];
        $.get('http://foobar.io/api/v1/listings/categories/').done(function (data) {
            $.each(data, function(index, element){
                rows.push(<OptionRow obj={element} />);
            });
           return (<Input type='select'>{rows}</Input>)

        })

    }
});

But i get the error below because i am returning render inside the done method of my ajax request.

但是我收到以下错误，因为我在我的 ajax 请求的 done 方法中返回渲染。

Uncaught Error: Invariant Violation: CategoriesSetup.render(): A valid ReactComponent must be returned. You may have returned undefined, an array or some other invalid object.

Uncaught Error: Invariant Violation: CategoriesSetup.render(): A valid ReactComponent must be returned. You may have returned undefined, an array or some other invalid object.

Is there a way to wait for my ajax request to end before start rendering?

有没有办法在开始渲染之前等待我的 ajax 请求结束？

回答by Michelle Tilley

There are two ways to handle this, and which you choose depends on which component should own the data and the loading state.

有两种方法可以处理这个问题，您选择哪种方法取决于哪个组件应该拥有数据和加载状态。

1. Move the Ajax request into the parent and conditionally render the component:

   var Parent = React.createClass({
     getInitialState: function() {
       return { data: null };
     },
   
     componentDidMount: function() {
       $.get('http://foobar.io/api/v1/listings/categories/').done(function(data) {
         this.setState({data: data});
       }.bind(this));
     },
   
     render: function() {
       if (this.state.data) {
         return <CategoriesSetup data={this.state.data} />;
       }
   
       return <div>Loading...</div>;
     }
   });
   

2. Keep the Ajax request in the component and render something else conditionally while it's loading:

   var CategoriesSetup = React.createClass({
     getInitialState: function() {
       return { data: null };
     },
   
     componentDidMount: function() {
       $.get('http://foobar.io/api/v1/listings/categories/').done(function(data) {
         this.setState({data: data});
       }.bind(this));
     },
   
     render: function() {
       if (this.state.data) {
         return <Input type="select">{this.state.data.map(this.renderRow)}</Input>;
       }
   
       return <div>Loading...</div>;
     },
   
     renderRow: function(row) {
       return <OptionRow obj={row} />;
     }
   });
   

1. 将 Ajax 请求移动到父级并有条件地渲染组件：

   var Parent = React.createClass({
     getInitialState: function() {
       return { data: null };
     },
   
     componentDidMount: function() {
       $.get('http://foobar.io/api/v1/listings/categories/').done(function(data) {
         this.setState({data: data});
       }.bind(this));
     },
   
     render: function() {
       if (this.state.data) {
         return <CategoriesSetup data={this.state.data} />;
       }
   
       return <div>Loading...</div>;
     }
   });
   

2. 将 Ajax 请求保留在组件中，并在加载时有条件地呈现其他内容：

   var CategoriesSetup = React.createClass({
     getInitialState: function() {
       return { data: null };
     },
   
     componentDidMount: function() {
       $.get('http://foobar.io/api/v1/listings/categories/').done(function(data) {
         this.setState({data: data});
       }.bind(this));
     },
   
     render: function() {
       if (this.state.data) {
         return <Input type="select">{this.state.data.map(this.renderRow)}</Input>;
       }
   
       return <div>Loading...</div>;
     },
   
     renderRow: function(row) {
       return <OptionRow obj={row} />;
     }
   });
   

回答by Roman

The basic example of async rendering of components is below:

组件异步渲染的基本示例如下：

import React                from 'react';
import ReactDOM             from 'react-dom';        
import PropTypes            from 'prop-types';

export default class YourComponent extends React.PureComponent {
    constructor(props){
        super(props);
        this.state = {
            data: null
        }       
    }

    componentDidMount(){
        const data = {
                optPost: 'userToStat01',
                message: 'We make a research of fetch'
            };
        const endpoint = 'http://example.com/api/phpGetPost.php';       
        const setState = this.setState.bind(this);      
        fetch(endpoint, {
            method: 'POST',
            body: JSON.stringify(data)
        })
        .then((resp) => resp.json())
        .then(function(response) {
            setState({data: response.message});
        });
    }

    render(){
        return (<div>
            {this.state.data === null ? 
                <div>Loading</div>
            :
                <div>{this.state.data}</div>
            }
        </div>);
    }
}