Sequelize Associations Error Users.hasMany called with something that's not a subclass of Sequelize.Model. when associating between 2 models

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英文:

Sequelize Associations Error Users.hasMany called with something that's not a subclass of Sequelize.Model. when associating between 2 models

问题

我在关联两个模型（Users 和 Comments）时遇到了一个错误：“Users.hasMany 调用的参数不是 Sequelize.Model 的子类。” 但是当我移除 const Users = require("./user"); 和 Comments.belongsTo(Users, { foreignKey: "userId", onDelete: "cascade" }); 这两行代码时，我会得到一个错误：“Users 未与 Comments 关联！” 我已经在用户模型中进行了关联。

这是我的Comments模型：

  1. const { DataTypes } = require("sequelize");
  2. const { sequelize } = require(".");
  3. const Users = require("./user");
  5. const Comments = sequelize.define("Comments", {
  6.     comment: {
  7.         type: DataTypes.STRING,
  8.         allowNull: false,
  9.         validate: {
  10.             min: 1,
  11.             max: 50,
  12.         },
  13.     },
  14. });
  15. // 如果我从代码中移除这部分，我会得到“Users 未与 Comments 关联！”的错误。
  17. Comments.belongsTo(Users, {
  18.     foreignKey: "userId",
  19.     onDelete: "cascade",
  20. });
  22. //
  24. module.exports = Comments;

这是我的Users模型：

  1. const { DataTypes } = require("sequelize");
  2. const { sequelize } = require(".");
  3. const Comments = require("./comment");
  4. const jwt = require("jsonwebtoken");
  6. const Users = sequelize.define("Users", {
  7.     username: {
  8.         type: DataTypes.STRING,
  9.         allowNull: false,
  10.         unique: true,
  11.         validate: {
  12.             min: 5,
  13.             max: 30,
  14.             notNull: true,
  15.         },
  16.     },
  17. });
  19. Users.hasMany(Comments, {
  20.     foreignKey: "userId",
  21.     onDelete: "cascade",
  22. });
  24. module.exports = Users;

我还有一个用于检索所有评论的 GET 请求，我想在其中包括 Users 表，以便我可以访问创建该评论的用户的用户名：

  1. const getComments = async (req, res) => {
  2.     const comments = await Comments.findAll({
  3.         include: Users,
  4.     });
  5.     res.send(comments);
  6. };
英文:

I am encountering an error Users.hasMany called with something that's not a subclass of Sequelize.Model. when associating between 2 models (Users and Comments). BUT when i remove const Users = require("./user"); and Comments.belongsTo(Users, { foreignKey: "userId", onDelete: "cascade", });
from the Comments model i instead get "Users is not associated to Comments!" error. I already associated it in the users model.

This is my model for Comments:

  1. const { DataTypes } = require("sequelize");
  2. const { sequelize } = require(".");
  3. const Users = require("./user");
  5. const Comments = sequelize.define("Comments", {
  6.     comment: {
  7.         type: DataTypes.STRING,
  8.         allowNull: false,
  9.         validate: {
  10.             min: 1,
  11.             max: 50,
  12.         },
  13.     },
  14. });
  15. // If i remove this from the code i instead get Users is not associated to Comments!
  17. Comments.belongsTo(Users, {
  18.     foreignKey: "userId",
  19.     onDelete: "cascade",
  20. });
  22. //
  24. module.exports = Comments;

This is my Users model:

  1. const { DataTypes } = require("sequelize");
  2. const { sequelize } = require(".");
  3. const Comments = require("./comment");
  4. const jwt = require("jsonwebtoken");
  6. const Users = sequelize.define("Users", {
  7.     username: {
  8.         type: DataTypes.STRING,
  9.         allowNull: false,
  10.         unique: true,
  11.         validate: {
  12.             min: 5,
  13.             max: 30,
  14.             notNull: true,
  15.         },
  16.     },
  17. });
  19. Users.hasMany(Comments, {
  20.     foreignKey: "userId",
  21.     onDelete: "cascade",
  22. });
  24. module.exports = Users;

I also have a GET request for retrieving all comments where I would like to include the Users table so that I have access to the username of the user that created that comment:

  1. const getComments = async (req, res) => {
  2.     const comments = await Comments.findAll({
  3.         include: Users,
  4.     });
  5.     res.send(comments);
  6. };

答案1

得分: 1

你可以定义一个单独的全局方法来处理关联：

  1. const Users = require("./user");
  2. const Comments = require("./comment");
  4. const sequelize = new Sequelize(...);
  6. export const sync = async () => {
  7.     Comments.belongsTo(Users, {
  8.         foreignKey: "userId",
  9.         onDelete: "cascade",
  10.     });
  12.     Users.hasMany(Comments, {
  13.         foreignKey: "userId",
  14.         onDelete: "cascade",
  15.     });
  17.     await sequelize.sync();
  18. }

然后，在初始化数据库/应用程序时使用它：

  1. import { sync } from './path/to/sync';
  3. await sync();

这将确保在关联时两个模型都已定义。

英文:

You could define a separate global method for handling associations:

  1. const Users = require("./user");
  2. const Comments = require("./comment");
  4. const sequelize = new Sequelize(...);
  6. export const sync = async () => {
  7.     Comments.belongsTo(Users, {
  8.         foreignKey: "userId",
  9.         onDelete: "cascade",
  10.     });
  12.     Users.hasMany(Comments, {
  13.         foreignKey: "userId",
  14.         onDelete: "cascade",
  15.     });
  17.     await sequelize.sync();
  18. }

Then, use it when initializing the database/application:

  1. import { sync } from './path/to/sync';
  3. await sync();

This will ensure both models are defined when associated.

huangapple
  • 本文由 发表于 2023年6月16日 01:25:57
  • 转载请务必保留本文链接：https://go.coder-hub.com/76484138.html
  • express
  • javascript
  • model
  • mysql
  • sequelize.js
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