javascript - 警告 : Each child in a list should have a unique "key" prop. - ReactJS

Question

我正在使用 ReactJS 构建一个看板应用程序，用户可以在其中向三个不同的“列”(Todos、Onprogress 和 Done)添加“卡片”。我遇到的问题是，应该显示在卡片中的内容没有按应有的方式显示，尽管我的状态返回它的对象很好(当我 console.log 一切时)。我认为问题是我将一个对象插入一个数组，然后将其作为值添加到状态中的一个键中，因此，当我使用 props 传递数据时，我的数据没有被正确读取。我将在下面分享我的所有代码库。

这是我的应用程序组件:

import React, { Component } from 'react';
  import Column from './Column';
  import AddCardForm from './AddCardForm';
  import './App.css';

class App extends Component {
    constructor(props) {
      super(props)
      this.state = {
        columns: [
          {
            name: 'Todos',
            cards: []
          },
          {
            name: 'Onprogress',
            cards: []
          },
          {
            name: 'Done',
            cards: []
          }, 
        ] 
      };
    };

    // componentDidMount() {
    //   const { coldata } = this.state.columns
    //   console.log(coldata);
    //   // this.ref = base.syncState();
    // }

    addCard = (card, otherStatus) => {
      console.log("Adding a Card");
      const cards = { ...this.state.columns.cards };
      cards[`card`] = card;
      
      let todosCards = []
      let onprogressCards = []
      let doneCards = []
      
      Object.values(otherStatus).map(function(value) {
        if (value.includes('Onprogress') && value.includes('Done')) {
              todosCards.push(cards)
        } else if (value.includes('Todos') && value.includes('Done')) {
              onprogressCards.push(cards);
        } else if (value.includes('Todos') && value.includes('Onprogress')) {
              doneCards.push(cards);
        }
        return(todosCards || onprogressCards || doneCards);  
      });

      console.log(todosCards);
      console.log(onprogressCards);
      console.log(doneCards);

        this.setState({
          columns: [
            { 
              name: 'Todos',
              cards: todosCards
            },
            { 
              name: 'Onprogress',
              cards: onprogressCards
            },
            { 
              name: 'Done',
              cards: doneCards
            },
          ] 
        });
    }
        
  render() {
    return (
  <div className="App">
   {Object.keys(this.state.columns).map(key => (
      <Column key={key} details={this.state.columns[key]} />
    ))}
      <AddCardForm addCard={this.addCard} />
  </div>
    );
  }
}
export default App;

这是我的专栏组件:

import React, {Component} from "react";
import Card from "./Card"


class Column extends Component {
    render() {
        return (
        <div className="column"> 
            <h1 className="Title">{this.props.details.name}</h1>
            {Object.keys(this.props.details.cards).map( keycard => (
                <Card keycard={keycard} data={this.props.details.cards[keycard]} /> 
            ))}     
        </div>
        );
    }
}

export default Column;

这是我的卡片组件:

    import React, {Component} from "react";


    class Card extends Component {
        render() {
            const {taskName, taskDescription, taskPeriod } = this.props.data;
            // const isTaskOn = taskStatus 
            return (
            <div className="card">
                <span className="title">{taskName}</span>
                <div className="description">
                    <h4>{taskDescription}</h4>
                </div>
                <div className="period">
                    <h4>{taskPeriod}</h4>
                </div>
                <div className="status">
                    <select>
                        <option value='Todos'>Todos</option>
                        <option value='Onprogress'>Onprogress</option>
                        <option value="Done">Done</option>
                    </select>
                </div>
            </div>  
            );
        }
    }

    export default Card;

这是我的 AddCardForm 组件:

import React, { Component } from 'react';


class AddCardForm extends Component {

    taskName = React.createRef();
    taskDescription = React.createRef();
    taskPeriod = React.createRef();
    taskStatus = React.createRef(); 

    addCardtoApp = event => {
        event.preventDefault();
        const card = {
            taskName: this.taskName.current.value, 
            taskDescription: this.taskDescription.current.value,
            taskPeriod: this.taskPeriod.current.value,
        };
        const cardStatus = this.taskStatus.current.value;
        let otherStatus = {
            otherStatus: this.taskStatus.current.textContent.replace(`${cardStatus}`, ''),
        };
        
        this.props.addCard(card, otherStatus);
        event.currentTarget.reset();
    };
    
    render() {
        return (
        <form onSubmit={this.addCardtoApp}>
        <label>
            Task Name:
            <input type="text" name="taskName" ref={this.taskName}/>
        </label> <br />
        <label>
            Description:
            <input type="text" name="taskDescription" ref={this.taskDescription} />
        </label> <br /> 
        <label>
            Period:
            <input type="text" name="taskPeriod" ref={this.taskPeriod} />
        </label> <br />
        <label>
            Task Status:
            <select type="text" name="taskStatus" ref={this.taskStatus}>
                <option value="Todos">Todos</option>
                <option value="Onprogress">Onprogress</option>
                <option value="Done">Done</option>
            </select>
        </label> <br />
        <input type="submit" value="Submit" />
        </form>
        );
    }
}

export default AddCardForm;

Answer 1

在任何使用循环构建 React 组件的地方，您都必须添加 Prop key 并为其传递一个唯一值。

您可以重新定义您的 map 调用以包含这样的索引:

Object.keys(this.state.columns).map((count, key) => (
    <Column key={count} details={this.state.columns[key]} />
))