// Define User model interface
interface UserAttributes {
  id: number;
  name: string;
  email: string;
}

interface UserInstance extends Sequelize.Instance<UserAttributes>, UserAttributes {}

const User = sequelize.define<UserInstance>('User', {
  id: {
    type: Sequelize.INTEGER,
    primaryKey: true,
    autoIncrement: true,
  },
  name: Sequelize.STRING,
  email: Sequelize.STRING,
});

// Define Post model interface
interface PostAttributes {
  id: number;
  title: string;
  content: string;
  userId: number;
}

interface PostInstance extends Sequelize.Instance<PostAttributes>, PostAttributes {}

const Post = sequelize.define<PostInstance>('Post', {
  id: {
    type: Sequelize.INTEGER,
    primaryKey: true,
    autoIncrement: true,
  },
  title: Sequelize.STRING,
  content: Sequelize.TEXT,
  userId: Sequelize.INTEGER,
});

// Define association between User and Post models
User.hasMany(Post, { foreignKey: 'userId' });
Post.belongsTo(User, { foreignKey: 'userId' });

module.exports = {
  up: async (queryInterface, Sequelize) => {
    await queryInterface.addColumn('Users', 'createdAt', Sequelize.DATE);
    await queryInterface.addColumn('Users', 'updatedAt', Sequelize.DATE);
  },

  down: async (queryInterface, Sequelize) => {
    await queryInterface.removeColumn('Users', 'createdAt');
    await queryInterface.removeColumn('Users', 'updatedAt');
  },
};

mkdir ts-sequelize
cd ts-sequelize

npm init -y
npm install typescript ts-node-dev @types/node --save-dev

{
  "compilerOptions": {
    "sourceMap": true,
    "outDir": "dist",
    "strict": true,
    "lib": [
      "esnext"
    ],
    "esModuleInterop": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "target": "esnext",
    "moduleResolution": "Node"
  }
}

{
  // ...
  "type": "module",
  "scripts": {
    "start": "ts-node-dev main.ts"
  },
  // ...
}

npm install express mariadb reflect-metadata sequelize sequelize-typescript --save
npm install @types/express @types/validator --save-dev

// Import required dependencies
import "reflect-metadata";
import express, { Request, Response } from "express";

// Create a new express app
const app = express();

// Enable express to parse JSON data
app.use(express.json());

// Define a route for the root URL
app.get("/", (req: Request, res: Response): Response => {
  return res.json({ message: "Sequelize Example 🤟" });
});

// Define a function to start the server
const start = async (): Promise<void> => {
  try {
    // Start listening on port 3000
    app.listen(3000, () => {
      console.log("Server started on port 3000");
    });
  } catch (error) {
    // Log any errors and exit the process
    console.error(error);
    process.exit(1);
  }
};

// Call the start function to start the server
void start();

// Import the Sequelize module from sequelize-typescript
import { Sequelize } from "sequelize-typescript";

// Import the Customer model from the ./models module
import { Customer } from "./models";

// Create a new Sequelize instance with the connection configuration
const connection = new Sequelize({
  dialect: "mariadb", // Specifies the database dialect
  host: "localhost", // Specifies the database host
  username: "root", // Specifies the database username
  password: "root", // Specifies the database password
  database: "sequelize", // Specifies the database name
  logging: false, // Disables logging of SQL queries
  models: [Customer], // Associates the Customer model with this Sequelize instance
});

// Export the connection object as the default module
export default connection;

// Import necessary modules
import "reflect-metadata";
import express, { Request, Response } from "express";

// Import the connection object from ./database
import connection from "./database";

// Create a new Express application
const app = express();

// ...

// Define an asynchronous function to start the server and sync the database
const start = async (): Promise<void> => {
  try {
    await connection.sync(); // Synchronizes the database with the defined models
    app.listen(3000, () => { // Starts the server on port 3000
      console.log("Server started on port 3000");
    });
  } catch (error) {
    console.error(error); // Logs any errors that occur
    process.exit(1); // Exits the process with an error status code
  }
};

void start(); // Invokes the start function to start the server

/**
 * GET all customers from the database
 * @returns an array of all customers
 */
app.get("/customers", async (req: Request, res: Response): Promise<Response> => {
  const allCustomers: Customer[] = await Customer.findAll();
  return res.status(200).json(allCustomers);
});

// GET a single customer by id
app.get("/customers/:id", async (req: Request, res: Response): Promise<Response> => {
  // Get the id parameter from the request URL
  const { id } = req.params;
  // Find the customer with the specified id using Sequelize's `findByPk()` method
  const customer: Customer