首页 文章

使用父组件在React中重新呈现子组件

提问于
浏览 次
0

我'm creating a simple app and I'm无法重新渲染子组件 . 当在父组件（App）中调用setState时，传递给子组件（CardContainer）的props不知道如何做到这一点 . 应用程序中的状态肯定会更改（它显示在console.logs中），但 I need CardContainer to re-render the array it maps over once the App state is changed . 有任何想法吗？谢谢！

这是应用程序代码（父组件）：

import React, { Component } from 'react';
import Header from './Header';
import AddButton from './AddButton';
import CardContainer from './CardContainer';
import style from '../style/App.css';



class App extends Component {
  constructor(props) {
    super(props);
    this.state = {
      cards: [{id: 1, title: 'first', text: 'Random stuff that is on the paage.'},
        {id: 2, title: 'second', text: 'More text goes here'},
        {id: 3, title: 'third', text: 'to doooo'}],
      cardSelected: false,
      selectedCard: []
    };
    this.addCard = this.addCard.bind(this);
    this.deleteCard = this.deleteCard.bind(this);
    this.openSelectedCard = this.openSelectedCard.bind(this);
    this.closeSelectedCard = this.closeSelectedCard.bind(this);
    this.editExistingCard = this.editExistingCard.bind(this);
  }

  openSelectedCard(card) {
    this.setState({
      cardSelected: true,
      selectedCard: card
    })
  }

  closeSelectedCard() {
    this.setState({
      cardSelected: false
    })
  }

  addCard() {
    let newId = this.state.cards.length + 2;
    this.openSelectedCard({id: newId, title: 'Untitled', text: 'Just start typing here.'});
    // this.state.cards.push('New Post It');
    // this.setState({
    //   cards: this.state.cards
    // })
  }

  editExistingCard(cardToEdit) {
    for (let i = 0; i < this.state.cards.length; i++) {
      if(this.state.cards[i].id === cardToEdit.id) {
        this.state.cards.splice(i, 1);
        this.state.cards.splice(i, 0, cardToEdit);
      }
    }
    this.setState({
      cards: this.state.cards
    }, () => {this.closeSelectedCard()})
  }

  deleteCard(index) {
    console.log(this.state.cards[index])
    this.state.cards.splice(index, 1);
    this.setState({
      cards: this.state.cards
    })
  }

  render() {
    return (
        <div className={style.appContainer}>
          <Header addCard={this.addCard}/>
          <CardContainer openSelectedCard={this.openSelectedCard} closeSelectedCard={this.closeSelectedCard} cards={this.state.cards} deleteCard={this.deleteCard} selectedCard={this.state.selectedCard} cardSelected={this.state.cardSelected} editExistingCard={this.editExistingCard}/>
        </div>
    );
  }
}

export default App;

这是CardContainer代码（子组件）：

import React, { Component } from 'react';
import Card from './Card';
import SelectedCard from './SelectedCard';
import style from '../style/CardContainer.css';



class CardContainer extends Component {
  constructor(props) {
    super(props);
    this.state = {
      selecedCard: [],
      cards: []
    };
  }

  componentWillMount() {
    this.setState({
      cards: this.props.cards
    })
  }

  render() {
    return (
        <div className={style.cardContainer}>
          {this.state.cards.map((card, index) => (
            <Card card={card} key={card.id} index={index} title={card.title} text={card.text} openSelectedCard={() => this.props.openSelectedCard(card)} deleteCard={this.props.deleteCard}/>
          ))}
          {this.props.cardSelected &&
            <div className={style.selectedCardComponentContainer}>
              <SelectedCard card={this.props.selectedCard} closeSelectedCard={this.props.closeSelectedCard} editExistingCard={this.props.editExistingCard}/>
            </div>
          }
        </div>
    );
  }
}

export default CardContainer;
javascript reactjs rendering setstate

5 回答

  • 0

    你在 componentWillMount 中调用setState，这样组件赢得't re-render because you'在一个甚至还没有渲染的组件中调用一个方法 . 你应该总是在 componentDidMount 上设置状态，这是在React Docs上...

    希望有帮助:)

    回复于
  • 0

    不要在子组件中使用 cards 状态 . 用户 this.props.cards 而不是whcih会在道具改变时重新渲染你的组件 . 如果仍然不起作用，请使用 component.forceUpdate()

    class CardContainer extends Component {
  render() {
    return (
        <div className={style.cardContainer}>
          {this.props.cards.map((card, index) => (
            <Card card={card} key={card.id} index={index} title={card.title} text={card.text} openSelectedCard={() => this.props.openSelectedCard(card)} deleteCard={this.props.deleteCard}/>
          ))}
          {this.props.cardSelected &&
            <div className={style.selectedCardComponentContainer}>
              <SelectedCard card={this.props.selectedCard} closeSelectedCard={this.props.closeSelectedCard} editExistingCard={this.props.editExistingCard}/>
            </div>
          }
        </div>
    );
  }
}
    回复于
  • 0

    这是 CardContainer 生命周期的问题 . 处于组件状态的 cards 变量仅在首次装入组件后才设置 . 每当组件道具更新时，您也需要设置它 .

    修复：你需要在你内部添加这样的东西 CardContainer 组件：

    componentWillReceiveProps(nextProps) {
  this.setState({
    cards: nextProps.cards
  });
}

    编辑：另一种解决方法是只使用组件 CardContainer 道具中已有的卡片 .

    回复于
  • 0

    子进程没有重新渲染，因为componentWillMount（已弃用以便停止使用它）和componentDidMount仅在初始启动时触发 . 另外我看到你已经在CardContainer组件中声明了一个空数组，即使你引入了props作为构造函数的参数 . 此外，SelectedCard组件正在接收props.selectedCard . 看起来你的卡片状态根本就没用了 .

    我希望你不介意我没有给你回答，但我认为你应该稍微看一下这些要点并重新评估你的代码结构 .

    回复于
  • 0

    感谢您的帮助！我发现我实际上需要在CardContainer的孩子Card组件中调用setState . 该卡是我想要重新渲染的实际组件，所以我应该考虑确保它也获得了setState . 我认为更新填充卡片的阵列就足够了 .

    回复于

相关问题