Building a TODO List Backend with Node.js, Express, MongoDB, and TypeScript

Certainly! Below is a simple example of a TODO list backend using Node.js, Express, MongoDB, and TypeScript. Before you start, make sure you have Node.js, npm, and MongoDB installed on your machine.

1. Create a new project folder and initialize it:

mkdir todo-backend
cd todo-backend
npm init -y

1. Install the necessary dependencies:

npm install express mongoose body-parser typescript ts-node @types/node @types/express @types/mongoose

1. Create a tsconfig.json file in the project root:

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "outDir": "./dist",
    "rootDir": "./src",
    "strict": true
  }
}

1. Create a src folder and add a server.ts file inside it:

// src/server.ts
import express from 'express';
import mongoose from 'mongoose';
import bodyParser from 'body-parser';
import { TodoRoutes } from './routes/todo.routes';

class App {
  public app: express.Application;
  public mongoUrl: string = 'mongodb://localhost:27017/todo';

  constructor() {
    this.app = express();
    this.config();
    this.mongoSetup();
    this.routes();
  }

  private config(): void {
    this.app.use(bodyParser.json());
    this.app.use(bodyParser.urlencoded({ extended: false }));
  }

  private mongoSetup(): void {
    mongoose.Promise = global.Promise;
    mongoose.connect(this.mongoUrl, { useNewUrlParser: true, useUnifiedTopology: true });
  }

  private routes(): void {
    const router = express.Router();
    this.app.use('/api', new TodoRoutes().getRoutes());
  }
}

const PORT = 3000;
const app = new App().app;

app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

1. Create a src/models/todo.model.ts file:

// src/models/todo.model.ts
import mongoose, { Schema, Document } from 'mongoose';

export interface ITodo extends Document {
  text: string;
  completed: boolean;
}

const TodoSchema: Schema = new Schema({
  text: { type: String, required: true },
  completed: { type: Boolean, default: false },
});

export default mongoose.model<ITodo>('Todo', TodoSchema);

1. Create a src/routes/todo.routes.ts file:

// src/routes/todo.routes.ts
import express, { Router } from 'express';
import TodoController from '../controllers/todo.controller';

export class TodoRoutes {
  private router: Router = express.Router();
  private todoController: TodoController = new TodoController();

  constructor() {
    this.config();
  }

  private config(): void {
    this.router.post('/todos', this.todoController.createTodo);
    this.router.get('/todos', this.todoController.getTodos);
    this.router.get('/todos/:id', this.todoController.getTodoById);
    this.router.put('/todos/:id', this.todoController.updateTodo);
    this.router.delete('/todos/:id', this.todoController.deleteTodo);
  }

  public getRoutes(): Router {
    return this.router;
  }
}

1. Create a src/controllers/todo.controller.ts file:

// src/controllers/todo.controller.ts
import { Request, Response } from 'express';
import Todo from '../models/todo.model';

export default class TodoController {
  public createTodo(req: Request, res: Response): void {
    const newTodo = new Todo(req.body);

    newTodo.save((err, todo) => {
      if (err) {
        res.status(400).json(err);
      } else {
        res.json(todo);
      }
    });
  }

  public getTodos(req: Request, res: Response): void {
    Todo.find({}, (err, todos) => {
      if (err) {
        res.status(400).json(err);
      } else {
        res.json(todos);
      }
    });
  }

  public getTodoById(req: Request, res: Response): void {
    Todo.findById(req.params.id, (err, todo) => {
      if (err) {
        res.status(400).json(err);
      } else {
        res.json(todo);
      }
    });
  }

  public updateTodo(req: Request, res: Response): void {
    Todo.findByIdAndUpdate(req.params.id, req.body, { new: true }, (err, todo) => {
      if (err) {
        res.status(400).json(err);
      } else {
        res.json(todo);
      }
    });
  }

  public deleteTodo(req: Request, res: Response): void {
    Todo.findByIdAndRemove(req.params.id, (err, todo) => {
      if (err) {
        res.status(400).json(err);
      } else {
        res.json(todo);
      }
    });
  }
}

1. Start your MongoDB server:

mongod

1. Compile TypeScript and run the server:

npx tsc
node dist/server.js

Now, your TODO list backend should be running on http://localhost:3000/api. You can use tools like Postman or CRUD to interact with the API or integrate it into a front-end application.