step-by-step guide on how to create a simple REST API using Node.js, MongoDB, Express, TypeScript, and Docker

Step 1: Initialize the project

Create a new directory for your project and navigate into it:

mkdir my-api

cd my-api

Initialize a new Node.js project:

npm init -y

Step 2: Install dependencies

Install the necessary packages:

npm install express mongoose body-parser

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

Step 3: Set up TypeScript

Initialize TypeScript in your project:

npx tsc --init

Edit the `tsconfig.json` to include the following:

{

  "compilerOptions": {

    "target": "es6",

    "module": "commonjs",

    "outDir": "./dist",

    "rootDir": "./src",

    "strict": true,

    "esModuleInterop": true

  },

  "include": ["src/**/*"]

}

Step 4: Create your Express server

Create a `src` directory and a `server.ts` file:

mkdir src

cd src

touch server.ts

In server.ts, set up a basic Express server:

import express from 'express';

import bodyParser from 'body-parser';

import mongoose from 'mongoose';

const app = express();

const PORT = 3000;

app.use(bodyParser.json());

app.get('/', (req, res) => {

    res.send('Hello World!');

});

app.listen(PORT, () => {

    console.log(`Server running on http://localhost:${PORT}`);

});

Step 5: Integrate MongoDB with Mongoose

Modify `server.ts` to include Mongoose for MongoDB integration:

mongoose.connect('mongodb://mongo:27017/mydatabase', {

    useNewUrlParser: true,

    useUnifiedTopology: true

}).then(() => console.log('MongoDB connected'))

  .catch(err => console.log(err));

// Define a schema and model

const Schema = mongoose.Schema;

const itemSchema = new Schema({

    name: String,

    quantity: Number

});

const Item = mongoose.model('Item', itemSchema);

// GET API to fetch all items

app.get('/items', async (req, res) => {

    try {

        const items = await Item.find();

        res.status(200).json(items);

    } catch (error) {

        res.status(500).json({ message: error.message });

    }

});

// POST API to add a new item

app.post('/items', async (req, res) => {

    const newItem = new Item({

        name: req.body.name,

        quantity: req.body.quantity

    });

    try {

        const savedItem = await newItem.save();

        res.status(201).json(savedItem);

    } catch (error) {

        res.status(400).json({ message: error.message });

    }

});

Step 6: Dockerize the application

Create a `Dockerfile` in the root directory:

FROM node:14

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 3000

CMD ["npm", "start"]

Create a `docker-compose.yml` file:

version: '3.8'

services:

  app:

    build: .

    ports:

      - "3000:3000"

    volumes:

      - .:/usr/src/app

    depends_on:

      - mongo

  mongo:

    image: mongo

    ports:

      - "27017:27017"

Step 7: Run your application

Build and run your Docker containers:

docker-compose up --build

This setup will give you a REST API running in a Docker container, connected to a MongoDB database, also running in a Docker container. Your API will have a `GET` endpoint at `/items` to fetch all items and a `POST` endpoint at `/items` to add new items.