Serverless Lambda调用Sequelize报hasMany参数非Model子类错误怎么解决？

使用Serverless框架的Lambda发起调用时，每次都会抛出如下错误：

[offline] _____ HANDLER RESOLVED _____
offline: Failure: product.hasMany called with something that's not a subclass of Sequelize.Model
Error: product.hasMany called with something that's not a subclass of Sequelize.Model
    at Function.hasMany (C:\Users\Kiran\Documents\Projects\Rentals-Backend\node_modules\sequelize\lib\associations\mixin.js:18:13)
    at Function.Product.associate (C:\Users\Kiran\Documents\Projects\Rentals-Backend\entity\product.js:21:17)

重要提示：以下代码为该错误的修复参考方案，若遇到同类问题可对照检查缺失步骤，解决思路由Stack Overflow用户Anatoly提供。

Product 模型代码 #

const { STRING, BOOLEAN, INTEGER } = require("sequelize");

module.exports = (sequelize, DataTypes) => {
    const Product = sequelize.define("product", {
        id: { type: INTEGER, primaryKey: true, autoIncrement: true },
        name: { type: STRING },
        description: { type: STRING, allowNull: true },
        purchase_price: { type: STRING },
        tax: { type: STRING },
        sale_price: { type: STRING },
        categoryId: { type: STRING },
        status: { type: BOOLEAN, defaultValue: 0 },
        created_on: { type: INTEGER, allowNull: true },
        updated_on: { type: INTEGER, allowNull: true },
    }, {
        timestamps: false,
        freezeTableName: true,
    })
    Product.associate = function (models) {
        Product.hasMany(models.product_image, { as: "images" });
        Product.belongsTo(models.product_category, { as: "category", foreignKey: 'categoryId' });
    };
    return Product;
}

图片（ProductImage）模型代码 #

const { STRING, BOOLEAN, INTEGER } = require("sequelize");

module.exports = (sequelize, DataTypes) => {
    const ProductImage = sequelize.define("product_image", {
        id: { type: INTEGER, primaryKey: true, autoIncrement: true },
        productId: { type: INTEGER },
        fileName: { type: STRING },
        url: { type: STRING },
        position: { type: INTEGER },
        isDefault: { type: BOOLEAN, defaultValue: 0 },
        shopId: { type: STRING },
        status: { type: BOOLEAN, defaultValue: 0 },
        created_on: { type: INTEGER, allowNull: true },
        updated_on: { type: INTEGER, allowNull: true },
    }, {
        timestamps: false,
        freezeTableName: true,
    })

    return ProductImage;
}

分类（ProductCategory）模型代码 #

const { STRING, BOOLEAN, INTEGER } = require("sequelize");


module.exports = (sequelize, DataTypes) => {
    const ProductCategory = sequelize.define("product_category", {
        id: { type: INTEGER, primaryKey: true, autoIncrement: true },
        name: { type: STRING },
        description: { type: STRING, allowNull: true },
        status: { type: BOOLEAN, defaultValue: 0 },
        created_on: { type: INTEGER, allowNull: true },
        updated_on: { type: INTEGER, allowNull: true },
    }, {
        timestamps: false,
        freezeTableName: true,
    });
    return ProductCategory;
}

Sequelize初始化配置文件代码 #

const Sequelize = require('sequelize')
const fs = require('fs')
const path = require('path')
const db = {}
const models = path.join(__dirname, '..', 'entity')
var basename = path.basename(module.filename)

const sequelize = new Sequelize(
    process.env.DB_NAME,
    process.env.DB_USER,
    process.env.DB_PASSWORD,
    {
        dialect: 'mysql',
        host: process.env.DB_HOST,
        port: process.env.DB_PORT,
        logging: false
    }
)

fs
  .readdirSync(models)
  .filter(function (file) {
    return (file.indexOf('.') !== 0) && (file !== basename) && (file.slice(-3) === '.js')
  })
  .forEach(function (file) {
    var model = require(path.join(models, file))(
      sequelize,
      Sequelize.DataTypes
    );
    db[model.name] = model;
  })

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

db.Sequelize = Sequelize
db.sequelize = sequelize

module.exports = db

产品详情调用逻辑代码 #

const db = require('../config/sequelize-config');
exports.getProductById = (query, username, shopId) => {
    return new Promise((resolve, reject) => {
        db.product.findOne({
            where: {
                id: query.id
            },
            attributes: ['id', 'name', 'description', ['purchase_price', 'purchasePrice'], 'tax', ['sale_price', 'salePrice']],
            include: [{
                model: db.product_image,
                as: 'images',
                where: {
                    status: 1
                },
                required: false,
                attributes: ['id', 'fileName', 'position', 'url']
            },
            {
                model: db.product_category,
                as: 'category',
                required: false,
                attributes: ['id', 'name']
            }]
        }).then(product => {
            if (product) {
                resolve({ [KEY_STATUS]: 1, [KEY_MESSAGE]: "Product details fetched successfully", [KEY_DATA]: product });
            } else {
                reject({ [KEY_STATUS]: 0, [KEY_MESSAGE]: "Product details fetch failed" });
            }
        }).catch(error => {
            reject({ [KEY_STATUS]: 0, [KEY_MESSAGE]: "Product details fetch failed", [KEY_ERROR]: error.message });
        });
    })
}

修复说明 #

该错误核心诱因是Sequelize关联注册时，传入的关联模型未被正确加载到全局db对象中，上述方案通过统一的模型扫描注册逻辑，保证所有模型在关联方法执行前都已完成实例化，同时关联关系注册步骤在所有模型加载完成后统一执行，避免了关联时找不到对应模型类的问题。

内容的提问来源于stack exchange，提问作者KIRAN K J