javascript - Node.js:返回原始 Promise 与新 Promise 实例

Question

我正在尝试修复一些真正 Promise 繁重的代码，我正在尝试通过删除新的 Promise 声明并返回初始 Promise 来修复，但我正在尝试确保我正确翻译了之前和之后。下面我有一个示例，概述了需要更改的场景之一。我是否在代码前后遗漏了某些内容，或者我是否朝着正确的方向前进？另外，之后我能捕获所有被拒绝的错误吗？

之前:

    add(book: IBook, authorId: string): Promise<IBookModel> {
        let p = new Promise((reject, resolve) => {
            let newBook: IBook = new Book({…book});
            newBook.createInitialSetup();
            let bookReady = {... newBook};
            this.bookRepository.add(bookReady)
                .then((completedBook: IBookModel) => {
                    this.bookRepository.findAuthorById(authorId)
                        .then((author: IAuthorModel) => {
                            let newBookAuthor: IAuthorModel = new Author();
                            newBookAuthor(completedBook._id, author._id);

                            let finalBookAuthor = {... newBookAuthor} as IAuthor;

                            this.bookRepository.addBookAuthor(finalBookAuthor)
                                .then((result: IBookAuthorModel) => {
                                    resolve(completedBook);
                                })
                                .catch((err: Error) => {
                                    reject(err);
                                });
                        })
                        .catch((err: Error) => {
                            reject(err);
                        });
                })
                .catch((err: Error) => {
                    reject(err);
                });
        });

        return p;
    }

之后:

    add(book: IBook, authorId: string): Promise<IBookModel> {
         let groupSetup: IGroupModel = new Group({...group});
         newBook.createInitialSetup();
         let bookReady = {... newBook};

         return this.bookRepository.add(bookReady)
                    .then((completedBook: IBookModel) => {
                        return this.bookRepository.findAuthorById(authorId)
                                   .then((author: IAuthorModel) => {
                                        let newBookAuthor: IAuthorModel = new Author();
                                         newBookAuthor(completedBook._id, author._id);

                                        let finalBookAuthor = {... newBookAuthor} as IAuthor;

                                        return this.bookRepository.addBookAuthor(finalBookAuthor)
                                                    .then((result: IBookAuthorModel) => {
                                                           return completedBook;
                                         });                  
                        });
         });
    }

Answer 1

Async/await 可能会让您的代码更易于理解和阅读:

async add(book: IBook, authorId: string): Promise<IBookModel> {
    let newBook: IBook = new Book({ ...book });
    newBook.createInitialSetup();
    let bookReady = { ...newBook };
    let completedBook: IBookModel = await this.bookRepository.add(bookReady)
    let author: IAuthorModel = await this.bookRepository.findAuthorById(memberId)

    let newBookAuthor: IAuthorModel = new Author();
    newBookAuthor(completedBook._id, author._id);

    let finalBookAuthor = { ...newBookAuthor } as IAuthor;

    let result: IBookAuthorModel = await this.bookRepository.addBookAuthor(finalBookAuthor);
    return completedBook
}

几点说明:

1. 不确定memberId是谁，原始代码中未定义
2. 您可以使用 try/catch 包围整个代码，但由于您所做的只是转发错误，因此不需要这样做，因为如果任何等待的 Promise 失败，则返回的 Promise 将被拒绝
3. 持保留态度，使用async/await的一般原理是有效的，但转换是在尖叫的婴儿背景下执行的，因此可能会出现错误。