session7.md

Session 7 - Backend File and Folder Structure

Agenda

1. Session Overview
2. Session Objectives
3. Recommended Project Structure
4. Route file Example
5. Controller file Example
6. Server.js file
7. Query Example
8. Params Example
9. Best Practices
10. Task

Session Overview

In this session, we will focus on restructuring backend project files and folders for better maintainability, scalability, and readability. Previously, we implemented CRUD operations using files instead of a database. Now, our goal is to refactor the code and apply best practices in structuring backend applications.

Session Objectives

By the end of this session, you will:

• Understand how to structure a backend project properly.
• Learn the separation of concerns in backend development.
• Refactor your existing code into a well-organized structure.
• Improve code maintainability and scalability.

Recommended Project Structure

Below is the recommended structure for organizing your backend files:

📦 project-root
├── 📁 controllers  # Handles business logic
│   ├── fileController.js
│   ├── userController.js
│
├── 📁 models       # Data models (if applicable)
│   ├── fileModel.js
│   ├── userModel.js
│
├── 📁 routes       # API routes
│   ├── fileRoutes.js
│   ├── userRoutes.js
│
├── 📁 middlewares  # Middleware functions (e.g., validation, authentication)
│   ├── authMiddleware.js
│   ├── errorHandler.js
│
├── 📁 utils        # Utility functions (helpers)
│   ├── fileHelper.js
│   ├── responseHelper.js
│
├── 📁 config       # Configuration files (e.g., environment variables)
│   ├── config.js
│
├── server.js       # Entry point of the application
├── package.json    # Project metadata and dependencies
└── README.md       # Documentation

Route file Example

OSC_CREW.router.js

const express = require("express");

// osc_crew controller
const controller = require("../controllers/OSC-Crew-controller");

const router = express.Router();

router.get("/", controller.get_all_data);
// Rest of routes

module.exports = router;

Controller file Example

OSC_CREW.controller

/* load data needed code is here
 *
 */
const get_all_data = (req, res) => {
  res.status(200).send({
    status: 200,
    data: osc_data,
  });
};

// Rest of methods for osc_crew logic

module.exports = {
  get_all_data,
  // Rest of methods
};

Server file

const express = require("express")

const app = express()
const PORT = 3000
app.use(express.json())

// Routers import
const osc_crew_router = require("./routes/OSC-Crew.router")
const products_router = require('./routes/products.router')

// Routers use
app.use('/osc-crew',osc_crew_router)
app.use('/products',products_router)

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

Query Example

Get data by type [Committees, Highboard or All data]

// osc_data = ALL DATA
const get_all_data = (req, res) => {
  const { type } = req.query;
  if (type) {
    let data = null;
    if (type.toLowerCase() === "committees") data = osc_data["Committees"];
    else if (type.toLowerCase() === "highboard") data = osc_data["Highboard"];
    if (data)
      return res.status(200).send({
        type: type,
        status: 200,
        data: data,
      });
    else
      return res.status(404).send({
        type: type,
        status: 404,
        data: "Not found !",
      });
  }
  res.status(200).send({
    status: 200,
    data: osc_data,
  });
};

Params Example

Get head name of a given committee localhost:3000/osc_crew/head/backend result meefr

// Helper function 
const find_head(committee){
    const heads = osc_data["Highboard"]["Heads"];
    committee = committee.toLowerCase(); 
    for (const category in heads) {
      for (const key in heads[category]) {
        if (key.toLowerCase() === committee) {
          return heads[category][key];
        }
      }
    }
    return null
}

// osc_data = ALL DATA
// url is -> localhost:3000/osc_crew/head/:committee
const get_head = (req, res) => {
  let { committee } = req.params;
  if (committee) {
    const head = find_head(committee)
    if (head)
      return res.status(200).send({
        status: 200,
        role: role,
        data: head,
      });
    else
      return res.status(404).send({
        status: 404,
        role: role,
        data: "Not found !",
      });
  }
};

Best Practices

• Separation of Concerns: Each file should have a specific responsibility.
• Error Handling: Use middleware to handle errors properly.
• Modular Code: Make reusable utility functions and middlewares.
• Consistent Naming: Follow a clear naming convention for files and folders.

Task

• Refactor your previous CRUD operations by following this structure. (Refactor means to edit and use your old code DON'T CREATE NEW ONE )
• Make sure to solve all issues.
• Create API Test on [Thunder Cline or Postman]

Bonus:

• Implement a middleware for error handling.