Summary
Highlights
The speaker greets everyone and confirms screen visibility. This session is day two of the internship, following day one where full-stack development, the MERN stack, the FoodGin project, and required installations were covered. The speaker emphasizes the importance of Node.js, VS Code, Git, MongoDB, and Postman for daily use and confirms coding will start today. Important administrative points are covered, such as downloading offer letters via web browser, issues related to LMS or offer letters should be emailed to a provided ID, and attendance is tied to quiz and assignment completion. The main goal is practical experience and project building. Quizzes will be live next week.
Today's session will venture into the backend world, focusing on creating the first server using Express.js. The server acts as the brain of the application, handling user requests, orders, and data. By the end, participants will have a running Express server, basic routes, connected MongoDB, and API testing capabilities using Postman. The speaker re-emphasizes the need for Node.js (for running JavaScript outside the browser), MongoDB Atlas (cloud database for storing user, restaurant, and order data), VS Code (code editor), Git (version control and tracking changes), GitHub (online project storage for portfolio), and Postman (for API testing without a frontend).
A detailed walkthrough of how to install VS Code and Node.js. For VS Code, users should go to the download page and select their operating system. Node.js installation is also straightforward. To verify Node.js installation, open the terminal and type 'node -v' to check the version. The focus then shifts to setting up a MongoDB Atlas account, which is a free cloud database. Users are guided to create a new project on MongoDB Atlas, name it (e.g., Food Order Project), and click 'Create Project'. The speaker advises against creating a cluster yet, as that will be done when coding begins.
The project follows a three-tier architecture: Presentation Layer (frontend with React), Application Layer (backend with Node.js and Express for business logic), and Database Layer (MongoDB for data storage). The backend mediates between the frontend and database, ensuring security and control. The flow is explained step-by-step: user action on React -> React sends HTTP request to backend -> Express receives request -> Backend validates (e.g., login status) -> Backend communicates with MongoDB -> MongoDB sends data back -> Server sends structured data to frontend -> User sees updated data. This entire process happens seamlessly. The frontend never directly communicates with the database; the backend acts as a manager. An analogy of a restaurant (customer=frontend, manager=backend, storeroom=database, special chef=AI) is used to simplify the concept. AI integration will come later.
The process of project initialization begins by creating a main folder (e.g., 'Food Delivery App'), then a 'backend' subfolder within it. Using VS Code, navigate into the 'backend' folder via the terminal (`cd backend`). The command `npm init -y` is then executed. NPM stands for Node Package Manager, used for managing project libraries. `init` initializes a new Node.js project, and `-y` automatically answers 'yes' to all default configuration questions, saving time. This command creates a `package.json` file, which acts as the 'heart' of the Node.js project, storing project details, version, and dependencies, crucial for managing packages and allowing easy project sharing.
With `package.json` created, the next step is to install essential packages: Express, Mongoose, CORS, and dotenv using `npm i express mongoose cors dotenv`. The speaker explains the purpose of each: Express (framework for Node.js to build web servers and APIs, simplifying HTTP logic), Mongoose (an Object Data Modeling (ODM) library for MongoDB and Node.js, acting as a translator between JavaScript and MongoDB query language), CORS (middleware that enables cross-origin requests, allowing frontend and backend to communicate when hosted on different domains or ports, acting as a security guard for APIs), and dotenv (for loading environment variables from a `.env` file, securing sensitive information like API keys and database credentials). After installation, a `node_modules` folder and updated `package.json` with dependencies are observed.
A `config` folder is created inside the `backend` directory, and within it, a `config.env` file. In `config.env`, `PORT=8080` is added to define the server's port. Then, two new files are created in the `backend` folder: `app.js` and `server.js`. `app.js` will configure Express and middleware, while `server.js` will start the server. The `app.js` file begins by importing `express` and `cors` packages. It then initializes the Express application (stored in the `app` variable). The concept of 'middleware' is explained as functions running between the request and response, processing tasks like security checks before the main logic. `app.use(cors())` is added to enable cross-origin communication, and `app.use(express.json())` is included to allow the server to parse incoming JSON data. Finally, `module.exports = app` is used to export the configured Express app for use in `server.js`.
In `server.js`, the `app` is imported from `app.js`, and the `dotenv` package is imported. `dotenv.config({ path: 'config/config.env' })` is used to load environment variables, specifically the `PORT` from `config.env`. The server is started using `app.listen()`, with the port dynamically accessed via `process.env.PORT`. A console log confirms the server's status and port. To run the server, a 'start' script is added to `package.json` under the `scripts` section: `"start": "node server.js"`. Running `npm start` in the terminal successfully starts the server, displaying 'Server started on port 8080'. This marks the successful setup of the backend server. The next session will focus on creating routes and testing them with Postman. Participants are encouraged to review the session recordings and post any issues on the LMS discussion forum for assistance.