NodeJS 无法导入 Sequelize.js 模型 (ES6)

Question

我正在使用 Express 和 Sequeulize 运行 NodeJS，并且我有一个文件controllers/rooms.js从models/room.js导入 Room 。

import Room from '../models'

export function list(req, res) {
    return Room
        .findAll()
        .then((rooms) => res.status(200).send(rooms))
        .catch((error) => res.status(400).send(error))
}

下面是models/room.js （同目录下还有sequelize-cli生成的index.js文件）

'use strict'

export default (sequelize, DataTypes) => {

    const Room = sequelize.define('Room', {
        name: DataTypes.STRING
    })

    return Room
}

我有一个路线app.get('/rooms', list) ，但是当我访问这条路线时，我收到了这个错误：

TypeError: _models2.default.findAll is not a function
    at list (/Users/matis/Documents/apps/node-docker-test/app/database/controllers/rooms.js:21:10)
    at Layer.handle [as handle_request] (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/layer.js:95:5)
    at next (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/route.js:137:13)
    at Route.dispatch (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/layer.js:95:5)
    at /Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:281:22
    at Function.process_params (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:275:10)
    at expressInit (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/middleware/init.js:40:5)
    at Layer.handle [as handle_request] (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:317:13)
    at /Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:275:10)
    at query (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/middleware/query.js:45:5)
    at Layer.handle [as handle_request] (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:317:13)
    at /Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:275:10)
    at Function.handle (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/router/index.js:174:3)
    at Function.handle (/Users/matis/Documents/apps/node-docker-test/node_modules/express/lib/application.js:174:10)

我确定我的导入/导出搞砸了，但我不知道怎么办。

models/index.js文件如下

'use strict'

import { readdirSync } from 'fs'
import { basename as _basename, join } from 'path'
import Sequelize from 'sequelize'
const basename = _basename(__filename)
const env = process.env.NODE_ENV || 'development'
const config = require(__dirname + '/../config/config.json')[env]
const db = {}

let sequelize
if (config.use_env_variable) {
    sequelize = new Sequelize(process.env[config.use_env_variable], config)
} else {
    sequelize = new Sequelize(config.database, config.username, config.password, config)
}

readdirSync(__dirname)
    .filter(file => {
        return (file.indexOf('.') !== 0) && (file !== basename) && (file.slice(-3) === '.js')
    })
    .forEach(file => {
        const model = sequelize['import'](join(__dirname, file))
        db[model.name] = model
    })

Object.keys(db).forEach(modelName => {
    if (db[modelName].associate) {
        db[modelName].associate(db)
    }
})

db.sequelize = sequelize
db.Sequelize = Sequelize

export default db

当我这样称呼它时它起作用： return Room.Room.findAll()...因此我可以将导入重命名为： import models from '../models'并以这种方式调用它： return models.Room.findAll()...

但是，为什么我不能将其称为return Room.findAll()... ，导入应该如何制定？？

Answer 1

假设您有使用 ES6 导入的 babel 设置，您可以尝试这种方法在 ES6 中导出 Sequelize 模型。

//数据库配置文件

 import Sequelize from 'sequelize'; export const sequelize = new Sequelize( config.database.name, config.database.user, config.database.password, { host: config.database.host, dialect: config.database.dialect, pool: config.database.pool, operatorsAliases: false } );

// 模型

 import Sequelize from 'sequelize'; import { sequelize } from '../database/db'; const User = sequelize.define( 'table_name', { id: { type: Sequelize.INTEGER, primaryKey: true, autoIncrement: true }, name: { type: Sequelize.STRING, allowNull: false }, email: { type: Sequelize.STRING, allowNull: false }, password: { type: Sequelize.STRING, allowNull: false } }, { freezeTableName: true } ); export default User;

Answer 2

上次我使用 Sequelize 时，它​​在 ES6 特性上运行不佳。 我的猜测是，由于export default ， models/room.js没有正确导出模型。 您可以尝试将该行更改为旧样式module.exports ；

export default (sequelize, DataTypes) => {
.....
To
.....
module.exports = (sequelize, DataTypes) => {

看看是否能解决导入问题。

在控制器中导入时，您可以这样做；

const Room = require('../models').Room;

这是进行导入的旧方法，现在您的代码应该可以工作了。 :)

如果您想尝试使用 ES6，您可以执行以下操作；

import {Room} from '../models'

我不确定这个 ES6 导入在这里是否有效！

Answer 3

我试图设置现有代码并面临上述问题。 通过将我的节点版本从最新版本降级到 10.18.0，问题得到了解决。

似乎代码最初是使用节点版本 10 开发的。