Question

我有一个基本的React应用程序，在App.js组件中有一个函数，作为后续组件的支柱传递，以处理在书架之间移动书籍。

当我将该函数向下传递一个级别时，从App.js传递到ListBooks.js以传递到Books.js组件，用户将在该组件上选择新的磁盘架并触发API调用和状态更新，这很好。

然而，当我尝试从App.js＆gt;做同样的事情时SearchBooks.js＆gt; Book.js它似乎不起作用。

我期望调用updateShelf函数来更新书籍和状态。

如果那里有太多的“代码墙”，请道歉，只是不确定问题的确切位置。

编辑：

正如评论中所建议的，这是CodeSandbox版本： https://codesandbox.io/s/github/richardcurteis/myreads-udacity

App.js

import React, { Component } from 'react'
import ListBooks from './ListBooks'
import SearchBooks from './SearchBooks'
import * as BooksAPI from './utils/BooksAPI'
import { Route } from 'react-router-dom'

class BooksApp extends Component {

  state = {
    books: []
  }

  componentDidMount() {
    BooksAPI.getAll()
    .then((books) => {
      this.setState(() => ({
        books
      }))
    })
  }

  updateShelf = (book, shelf) => {
    this.state.books.forEach(b => {
      if(b.id === book.id) {
        b.shelf = shelf
        this.setState((currentState) => ({
          books: currentState.books
        }))
        BooksAPI.update(book, shelf)
      }
    });
  }

  render() {
    return (
      <div>
        <Route exact path='/' render={() => (
          <ListBooks
          books={this.state.books}
          onUpdateShelf={this.updateShelf}
          />
        )} />
        <Route exact path='/search' render={() => (
          <SearchBooks
          onUpdateShelf={this.updateShelf}
          />
        )} />
      </div>
    )
  }
}
export default BooksApp

SearchBooks.js

import React, { Component } from 'react'
import * as BooksAPI from './utils/BooksAPI'
import Book from './Book';

export default class SearchBooks extends Component {

    state = {
        query: '',
        books: []
    }

    updateQuery(query) {
        this.setState(() => ({
            books: [],
            query: query
        }))
        this.bookSearch(query)
    }

    bookSearch(e) {
        if (e.length > 0) BooksAPI.search(e)
        .then(books => this.setState(currentState => ({
            books: books
        })));
     }


    render() {

        const { query, books } = this.state
        const { onUpdateShelf } = this.props

        return(
            <div className="search-books">
                <div className="search-books-bar">
                  <a className="close-search" >Close</a>
                  <div className="search-books-input-wrapper">
                    <input
                        type="text"
                        placeholder="Search by title, author or subject"
                        value={query}
                        onChange={(event) => this.updateQuery(event.target.value)}
                    />
                  </div>
                </div>
                <div className="search-books-results">
                  <ol className="books-grid">
                    <li>
                      { !books.error ? (
                        books.map((book) => (
                          <Book
                            key={book.id}
                            book={book}
                            updateShelf={onUpdateShelf}
                             />
                          ))
                        ) : (
                          <h4>"{query}", is not a valid search</h4>
                        )}
                    </li>
                  </ol>
                </div>
            </div>
        )
    }
}

Book.js

import React, { Component } from 'react'
import PropTypes from 'prop-types'


class Book extends Component {

    static propTypes = {
        book: PropTypes.object.isRequired
    }    

    render() {

        const { book, updateShelf } = this.props

        return(
            <div key={book.id} className="book">
                <div className="book-top">
                    <div className="book-cover" style={{ width: 128, height: 193, backgroundImage: `url(${book.imageLinks.thumbnail})` }}></div>
                        <div className="book-shelf-changer"> 
                            <select value={book.shelf ? book.shelf : 'none'} onChange={(e) => updateShelf(book, e.target.value)}>
                                <option disabled >Move to...</option>
                                <option value="currentlyReading" >Currently Reading</option>
                                <option value="wantToRead" >Want to Read</option>
                                <option value="read" >Read</option>
                                <option value="none" >None</option>
                            </select>
                        </div>
                </div>
                <div className="book-title">{book.title}</div>
                <div className="book-authors">{book.authors}</div>
            </div>
        )
    }
}

export default Book

仅供参考：

ListBooks.js

import React, { Component } from 'react';
import PropTypes from 'prop-types'
import './App.css'
import { Link } from 'react-router-dom'
import Book from './Book'

const shelves = [
  {
    key: 'currentlyReading',
    name: 'Currently Reading'
  },
  {
    key: 'wantToRead',
    name: 'Want To Read'
  },
  {
    key: 'read',
    name: 'Read'
  }
];

class ListBooks extends Component {

    static propTypes = {
       books: PropTypes.array.isRequired,
       onUpdateShelf: PropTypes.func.isRequired
    }

    render() {

        const { books, onUpdateShelf } = this.props

        function getBooksForShelf(shelfKey) {
          return books.filter(book => book.shelf === shelfKey);
        }

        return(
            <div className="app">
              <div className="list-books">
                <div className="list-books-title">
                  <h1>My Reads</h1>
                </div>
                <div className="list-books-content">
                  <div>
                    { shelves.map((shelf) => (
                      <div key={shelf.key} className="bookshelf">
                        <h2 className="bookshelf-title">{shelf.name}</h2>
                        { getBooksForShelf(shelf.key).length === 0 ? (
                          <div>
                            <h4>No books in this shelf</h4>
                          </div>
                        ) : (
                          <div className="bookshelf-books">
                            <ol className="books-grid">
                              <li>
                                { getBooksForShelf(shelf.key).map((book) => (
                                 <Book key={book.id}
                                     book={book}
                                     updateShelf={onUpdateShelf}/>
                                  ))}
                              </li>
                            </ol>
                          </div> 
                        )}
                      </div>
                    )) }
                  </div>
                </div>
                  <Link
                     to='/search'
                      className="open-search">
                      Find a Book
                  </Link>
              </div>

            </div>
        )
    }
}

export default ListBooks

Answer 1

正如我们所讨论的那样，道具传球不是问题，而是更新状态。以下是修改后的代码：

  updateShelf = (book, shelf) => {
    const bookFromState = this.state.books.find(b => b.id === book.id);
    if (bookFromState) {
      // update existing
      bookFromState.shelf = shelf;
      this.setState(currentState => ({
        books: currentState.books
      }));
      BooksAPI.update(book, shelf);
    } else {
      // add new one
      this.setState(prevState => ({ books: [...prevState.books, book] }));
      BooksAPI.update(book, shelf);
    }
  };

或者更好而不改变状态：

updateShelf = (book, shelf) => {
  this.setState(prevState => { 
    const booksCopy = prevState.books.filter(b => b.id !== book.id);
    booksCopy.push({ ...book, shelf });
    return { books: booksCopy } 
  });
  BooksAPI.update(book, shelf);
};

反应传递函数作为道具

1 个答案: