获取 Bookshelf.js 模型时 "new" 的用法有何不同？

Question

Bookshelf.js 文档有带 "new" 和不带 "new" 的代码示例：

这里http://bookshelfjs.org/#Model-instance-hasMany

let Author = bookshelf.Model.extend({
  tableName: 'authors',
  books: function() {
    return this.hasMany(Book);
  }
});

// select * from `authors` where id = 1
// select * from `books` where author_id = 1
Author.where({id: 1}).fetch({withRelated: ['books']}).then(function(author) {
  console.log(JSON.stringify(author.related('books')));
});

但是这里http://bookshelfjs.org/#Model-instance-fetch

let Book = bookshelf.Model.extend({
  tableName: 'books',
  editions: function() {
    return this.hasMany(Edition);
  },
  chapters: function{
    return this.hasMany(Chapter);
  },
  genre: function() {
    return this.belongsTo(Genre);
  }
})

new Book({'ISBN-13': '9780440180296'}).fetch({
  withRelated: [
    'genre', 'editions',
    { chapters: function(query) { query.orderBy('chapter_number'); }}
  ]
}).then(function(book) {
  console.log(book.related('genre').toJSON());
  console.log(book.related('editions').toJSON());
  console.log(book.toJSON());
});

那有什么区别呢？

Answer 1

没有区别。

Model.fetch、Model.query、Model.where 和 Model.fetchAll 是 shorthands for:

Model[method] = function(...args) {
  return Model.forge()[method](...args);
}

而 Model.forge 是 shorthand 对于 new。

Model.forge = function(...args) {
  return new this.constructor(...args);
}

获取 Bookshelf.js 模型时 "new" 的用法有何不同？

What is the difference in usage "new" while fetching Bookshelf.js models?

javascript

promise

bookshelf.js

knex.js