Question

我有一个菜单按钮，按下该按钮时必须添加一个新组件。似乎可行（如果我手动调用该函数以添加显示的组件）。问题是，如果我单击该按钮，它们将不会显示，我想是因为我应该使用setState重绘它们。我不确定如何在另一个函数/组件中调用另一个组件的setState。

这是我的index.js

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import Menu from './Menu';
import * as serviceWorker from './serviceWorker';
import Blocks from './Block.js';


ReactDOM.render(
    <div className="Main-container">
        <Menu />
        <Blocks />
    </div>
    , document.getElementById('root'));

// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers:
serviceWorker.unregister();

然后我有了Menu.js

import React from 'react';
import './Menu.css';
import {blocksHandler} from './Block.js';

class Menu extends React.Component {

  constructor(props) {

    super(props);
    this.state = {value: ''};

    this.handleAdd = this.handleAdd.bind(this);

  }

  handleAdd(event) {
    blocksHandler.add('lol');
    console.log(blocksHandler.render());
  }

  render() {
    return (
      <div className="Menu">
        <header className="Menu-header">
          <button className="Menu-button" onClick={this.handleAdd}>Add block</button>
        </header>
      </div>
    );
  }
}

export default Menu;

最后是Block.js

import React from 'react';
import './Block.css';

// this function adds components to an array and returns them

let blocksHandler = (function() {
    let blocks = [];
    return {
        add: function(block) {
            blocks.push(block);
        },
        render: function() {
            return blocks;
        }
    }
})();

class Block extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            title: '',
            content: ''
        };

        this.handleChange = this.handleChange.bind(this);
        this.handleSubmit = this.handleSubmit.bind(this);
    }

    handleChange(event) {
        this.setState({[event.target.name]: event.target.value});
    }

    handleSubmit(event) {
        alert('A name was submitted: ' + this.state.title);
        event.preventDefault();
    }

    render() {
      return (
        <div className="Block-container">
            <form onSubmit={this.handleSubmit}>
            <div className="Block-title">
                <label>
                    Block title:
                    <input type="text" name="title" value={this.state.value} onChange={this.handleChange} />
                </label>
            </div>
            <div className="Block-content">
                <label>
                    Block content:
                    <input type="text" name="content" value={this.state.value} onChange={this.handleChange} />
                </label>
            </div>
            <input type="submit" value="Save" />
            </form>
        </div>
      );
    }
}

class Blocks extends React.Component {

    render() {
        return (
            <div>
                {blocksHandler.render().map(i => (
                    <Block key={i} />
                ))}
            </div>
        )
    }
}


export default Blocks;
export {blocksHandler};

我是一名React初学者，所以我什至不确定我的方法是正确的。感谢您提供的任何帮助。

Answer 1

下面，我介绍了一个非常简单的“父/子”类型设置，..

Parent负责渲染按钮，我在这里只使用了一个简单的编号数组。当您单击任何按钮时，它将在父级中调用setState，这反过来会导致父级重新呈现其子级。

注意：我还使用了React Hooks来做这个，我只是找到了更多自然且易于使用。您可以使用类，相同的原理适用。

const {useState} = React;

function Child(props) {
  const {caption} = props;
  const {lines, setLines} = props.pstate;
  return <button onClick={() => {
    setLines([...lines, lines.length]);
  }}>
    {caption}
  </button>;
}

function Parent(props) {
  const [lines, setLines] = useState([0]);  
  return lines.map(m => <Child key={m} caption={`Click ${m}`} pstate={{lines, setLines}}/>);
}


ReactDOM.render(<React.Fragment>
  <Parent/>
</React.Fragment>, document.querySelector('#mount'));

<script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<div id="mount"></div>

Answer 2

您可以将其放置在Menu.js旁边，而不是像单独的功能那样创建blocksHandlers，如下所示 *

class Block extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            title: '',
            content: ''

        };
        this.handleChange = this.handleChange.bind(this);
        this.handleSubmit = this.handleSubmit.bind(this);
    }


    handleChange(event) {
        this.setState({[event.target.name]: event.target.value});
    }

    handleSubmit(event) {
        alert('A name was submitted: ' + this.state.title);

   event.preventDefault();
    }

    render() {
      return (
        <div className="Block-container">
            <form onSubmit={this.handleSubmit}>
            <div className="Block-title">
                <label>
                    Block title:
                    <input type="text" name="title" value={this.state.value} onChange={this.handleChange} />
                </label>
            </div>
            <div className="Block-content">
                <label>
                    Block content:
                    <input type="text" name="content" value={this.state.value} onChange={this.handleChange} />
                </label>
            </div>
            <input type="submit" value="Save" />
            </form>
        </div>
      );
    }
}

Menu.js

class Menu extends React.Component {

  constructor(props) {

    super(props);
    this.state = {value: '',blocksArray:[]};

    this.handleAdd = this.handleAdd.bind(this);

  }

  handleAdd() {
   this.setState({
        blocksArray:this.state.blocksArray.push(block)
     })

  }

renderBlocks = ()=>{
      this.state.blocksArray.map(block=> <Block/>)
 }
  render() {
    return (
      <div className="Menu">
        <header className="Menu-header">
          <button className="Menu-button" onClick={()=>this.handleAdd()}>Add block</button>
        </header>
    {this.renderBlocks()}

      </div>
    );
  }
}

export default Menu;

ReactJS：单击即可动态添加组件

2 个答案: