React Invariant Violation：对象作为 React 子对象无效

Question

我有以下代码：

import ReactDom from 'react-dom';
import React from 'react';
import {render} from 'react-dom';
import $ from 'jquery';


class App extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            data: '',
            loading: true
        }
    }
    componentDidMount () {
        const newsfeedURL = 'https://s3-eu-west-1.amazonaws.com/streetlife-coding-challenge/newsfeed.json';
        $.get(newsfeedURL, function(result) {
            this.setState({
                data: JSON.parse(result),
                loading: false
            });
            console.log(typeof this.state.data.messages);
        }.bind(this));
    }
    render () {
      let content;
      if (this.state.loading === false && this.state.data.messages) {
        content = Object.keys(this.state.data.messages).map(key => {
         return <div key={key}>Key: {key}, Value: {this.state.data.messages[key]}</div>;
        })
      } else { 
        content = ''; // whatever you want it to be while waiting for data
      }
      return (
        <div>
          {content}
        </div>
      )
    }
}


ReactDom.render(
  <App />,
  document.getElementById('app')
);

但我收到以下错误：

未捕获的不变违规：对象作为 React 子级无效（发现：具有键 {body、附件、视频、主题、updated_at、id、主题、downvotes、author、posted_at、cmets、user_vote、upvotes 的对象、状态、标签、位置、track_impact、user_is_following、cmets_count}）。如果您打算渲染一组子项，请改用数组或使用 React 附加组件中的 createFragment(object) 包装对象。检查App的渲染方法。

我看过这个答案，但对我的情况没有帮助：Invariant Violation: Objects are not valid as a React child

Answer 1

在您的 div 中，您正在尝试渲染 Value: {this.state.data.messages[key]} 这是一个对象。你不能使用 React 的 JSX 直接渲染对象。但是，您可以呈现的是该对象中保存的一些实际原始数据类型（例如字符串、数字），例如 Value: {this.state.data.messages[key].body} 将呈现对象的 body 属性中保存的字符串值。这是一个演示：http://codepen.io/PiotrBerebecki/pen/bwowxP

class App extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            data: '',
            loading: true
        }
    }
    componentDidMount () {
        const newsfeedURL = 'https://s3-eu-west-1.amazonaws.com/streetlife-coding-challenge/newsfeed.json';
        $.get(newsfeedURL, function(result) {
            this.setState({
                data: JSON.parse(result),
                loading: false
            });
            console.log(typeof this.state.data.messages);
        }.bind(this));
    }
    render () {
      let content;
      if (this.state.loading === false && this.state.data.messages) {
        content = Object.keys(this.state.data.messages).map(key => {
         console.log(this.state.data.messages[key])
         return <div key={key}><b>Key: {key},</b> Value: {this.state.data.messages[key].body}</div>;
        })
      } else { 
        content = ''; // whatever you want it to be while waiting for data
      }
      return (
        <div>
          {content}
        </div>
      )
    }
}


ReactDOM.render(
  <App />,
  document.getElementById('app')
);

Answer 2

class App extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            data: '',
            loading: true
        }
    }
    componentDidMount () {
        
        const newsfeedURL = 'https://s3-eu-west-1.amazonaws.com/streetlife-coding-challenge/newsfeed.json';
                $.get(newsfeedURL, function(result) {
                    this.setState({
                        data: result,
                        loading: false
                    });
                }.bind(this));
    }
    render () {
      let content;
      if (this.state.loading === false && this.state.data.messages) {
        content = this.state.data.messages.map((ele,key) => {
         return <div key={key}>id: {this.state.data.messages[key].id}</div>;
        })
      } else { 
        content = ''; // whatever you want it to be while waiting for data
      }
      return (
        <div>
          {content}
        </div>
      )
    }
}


ReactDOM.render(
  <App />,
  document.getElementById('app')
);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id="app"></div>