sequelize的文档为什么建议用sequelize.import()的方式将model来分成模块

Question

koa或express中用sequelize一般都要把一个个model放到单文件,官方文档给了一个奇怪的做法，它自己提供了个import的方法，然后让model单文件导出一个函数

// in your server file - e.g. app.js
const Project = sequelize.import(__dirname + "/path/to/models/project")

// The model definition is done in /path/to/models/project.js
// As you might notice, the DataTypes are the very same as explained above
module.exports = (sequelize, DataTypes) => {
  return sequelize.define("project", {
    name: DataTypes.STRING,
    description: DataTypes.TEXT
  })
}

https://github.com/sequelize/...
这个官方样例更详细

但是我觉得我这样写，模块化会更舒服一点

// sequelize.js
import Sequelize from 'sequelize'
const sequelize = new Sequelize({
    ...
})
export default sequelize

// model/modelA.js
import Sequelize from 'sequelize'
import sequelize from './sequelize'
export default sequelize.define("project", {
    name: Sequelize.STRING,
    description: Sequelize.TEXT
})


// in route
import modelA from 'path/to/model/modelA'

// or by using model/index.js
import { modelA } from 'path/to/model'

不知道我的想法会有什么问题

Answer 1

解决nodejs require module时循环引用会导致undefined的问题
这个一般在定义关联的时候会用。
目前我的做法是把所有model的关联放到一个js去做

import { Authorize, AuthorizeAttributes, AuthorizeInstance } from './authorize';
import { Comment, CommentAttributes, CommentInstance } from './comment';
import { Hit, HitAttributes, HitInstance } from './hit';
import { Moneylog, MoneylogAction, MoneylogAttributes, MoneylogInstance } from './moneylog';
import { Order, OrderAttributes, OrderInstance } from './order';
import { Post, PostAttributes, PostContentType, PostInstance } from './post';
import { Poundage, PoundageAttributes, PoundageInstance } from './poundage';
import { User, UserAttributes, UserInstance } from './user';
import { Withdrawal, WithdrawalAttributes, WithdrawalInstance } from './withdrawal';

Comment.belongsTo(Post, { foreignKey: 'post_id', as: 'post' });
Comment.belongsTo(User, { foreignKey: 'user_id', as: 'user' });

Order.belongsTo(User, { foreignKey: 'user_id', as: 'user' });
Order.belongsTo(Post, { foreignKey: 'post_id', as: 'post' });

Post.belongsTo(User, { foreignKey: 'user_id', as: 'user' });
Post.hasMany(Comment, { foreignKey: 'post_id', as: 'commentList' });

User.hasMany(Post, { foreignKey: 'user_id', as: 'posts' });
User.hasMany(Order, { foreignKey: 'user_id', as: 'orders' });
User.hasMany(Comment, { foreignKey: 'user_id', as: 'comment' });