Sequelize Model Not Creating Table in MySQL Database (TypeError: Cannot read properties of undefined (reading 'define'))

I’m working on a Node.js project using Sequelize with MySQL. The database connection is established successfully, and sequelize.sync({ alter: true }) runs without errors, but my users table is not being created.

Additionally, I’m getting the following error when requiring my model:

TypeError: Cannot read properties of undefined (reading 'define')
at Object.<anonymous> (B:\Builds\React-Express\nakargo\server\config\models\user.models.js:4:29)
at Module._compile (node:internal/modules/cjs/loader:1546:14)
at Object..js (node:internal/modules/cjs/loader:1689:10)
at Module.load (node:internal/modules/cjs/loader:1318:32)
at Function._load (node:internal/modules/cjs/loader:1128:12)
at TracingChannel.traceSync (node:diagnostics_channel:315:14)
at wrapModuleLoad (node:internal/modules/cjs/loader:218:24)
at Module.require (node:internal/modules/cjs/loader:1340:12)
at require (node:internal/modules/helpers:141:16)
at Object.<anonymous> (B:\Builds\React-Express\nakargo\server\config\db\dbConnection.js:24:19)

Here’s my setup:

user.models.js file

const { Sequelize, DataTypes } = require("sequelize");
const { sequelize } = require("../db/dbConnection");

const userModel = sequelize.define(
  "User",
  {
    id: {
      type: DataTypes.UUID,
      defaultValue: Sequelize.UUIDV4,
      primaryKey: true,
    },
    name: {
      type: DataTypes.STRING,
      allowNull: false,
    },
    email: {
      type: DataTypes.STRING,
      allowNull: false,
      unique: true,
      validate: {
        isEmail: true,
      },
    },
    password: {
      type: DataTypes.STRING,
      allowNull: false,
    },
  },
  {
    tableName: "users", // ✅ Explicit table name
    timestamps: true,
  }
);

module.exports = userModel; // ✅ Ensure model is exported correctly

db/dbConnection.js file

const { Sequelize } = require("sequelize");
const {
  DATABASE_NAME,
  DATABASE_USER,
  DATABASE_PASSWORD,
  DATABASE_HOST,
  DATABASE_PORT,
} = require("../envExports");

const sequelize = new Sequelize(
  DATABASE_NAME,
  DATABASE_USER,
  DATABASE_PASSWORD,
  {
    host: DATABASE_HOST,
    port: DATABASE_PORT,
    dialect: "mysql",
    logging: console.log, 
  }
);


const userModel = require("../models/user.models"); 

// Function to test database connection
const initializeDB = async () => {
  try {
    await sequelize.authenticate();
    console.log("✅ Database connection established successfully.");

    await sequelize.sync({ alter: true }); 
    console.log("✅ All models were synchronized successfully.");
  } catch (error) {
    console.error("❌ Failed to connect to the database:", error.message);
    process.exit(1); // Exit on critical failure
  }
};

// Function to clean up the connection
const disconnectDB = async () => {
  try {
    await sequelize.close();
    console.log("✅ Database connection closed successfully.");
  } catch (error) {
    console.error(
      "❌ Error while closing the database connection:",
      error.message
    );
  }
};

module.exports = { sequelize, initializeDB, disconnectDB, userModel }; 

Issue:

• sequelize.authenticate() works fine, and I see "✅ Database connection established successfully."
• sequelize.sync({ alter: true }) runs without errors, and "✅ All models were synchronized successfully." appears in the logs.
• However, the users table is not being created in MySQL. Running SHOW TABLES; in MySQL does not list users.
• I have also tried sequelize.sync({ force: true }), but no table is created.

What I Have Tried:

• Verified that MySQL is running and connected.
• Checked Sequelize logs (logging: console.log)—no CREATE TABLE statement appears.
• Restarted nodemon after every change.
• Manually checked MySQL with SHOW TABLES;.
• Tried explicitly calling userModel.sync({ force: true }).

Question:

• Why is my Sequelize model not creating a table in MySQL, and how can I fix the TypeError: Cannot read properties of undefined (reading 'define') error?
• Any insights would be greatly appreciated!

This is a case where 2 or more modules depend on each other by sharing program elements. For example, a module A imports from B and at same time, B imports from A. We can summarise the dependency like so (A -> B -> A).

The problem here, based on how module loading works is that Node.js while loading A will find B and while loading B, will discover B requires again module A. In other to avoid an infinite loop, Node.js will return an incompletely loaded module A in B which will result in undefined imports in module B.

A quick fix would be:

• remove sequelize.define from user.model.js
• only export its contents
• use sequelize.define in dbConnection.js and pass the object data in it
• tada: circular dependency is gone

In practice this would be something like:

user.models.js:

const { Sequelize, DataTypes } = require("sequelize");

const userModel = {
  name: "User",
  data: {
    id: {
      type: DataTypes.UUID,
      defaultValue: Sequelize.UUIDV4,
      primaryKey: true,
    },
    name: {
      type: DataTypes.STRING,
      allowNull: false,
    },
    email: {
      type: DataTypes.STRING,
      allowNull: false,
      unique: true,
      validate: {
        isEmail: true,
      },
    },
    password: {
      type: DataTypes.STRING,
      allowNull: false,
    },
  },
  {
    tableName: "users", // ✅ Explicit table name
    timestamps: true,
  }
};

module.exports = userModel; // ✅ Ensure model is exported correctly

dbConnection.js:

const { Sequelize } = require("sequelize");
const {
  DATABASE_NAME,
  DATABASE_USER,
  DATABASE_PASSWORD,
  DATABASE_HOST,
  DATABASE_PORT,
} = require("../envExports");

const sequelize = new Sequelize(
  DATABASE_NAME,
  DATABASE_USER,
  DATABASE_PASSWORD,
  {
    host: DATABASE_HOST,
    port: DATABASE_PORT,
    dialect: "mysql",
    logging: console.log, 
  }
);


const userModel = require("../models/user.models"); 
const userTable = sequelize.define(userModel.name, userModel.data);

// Function to test database connection
const initializeDB = async () => {
  try {
    await sequelize.authenticate();
    console.log("✅ Database connection established successfully.");

    await sequelize.sync({ alter: true }); 
    console.log("✅ All models were synchronized successfully.");
  } catch (error) {
    console.error("❌ Failed to connect to the database:", error.message);
    process.exit(1); // Exit on critical failure
  }
};

// Function to clean up the connection
const disconnectDB = async () => {
  try {
    await sequelize.close();
    console.log("✅ Database connection closed successfully.");
  } catch (error) {
    console.error(
      "❌ Error while closing the database connection:",
      error.message
    );
  }
};

module.exports = { sequelize, initializeDB, disconnectDB, userTable };