📝 Todo Task Management API

A production-ready RESTful API for managing tasks, built with Node.js, Express.js, and MongoDB following the MVC architecture pattern.

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📌 Project Overview

This project is a complete backend solution for a To-Do / Task Management application. It provides a clean REST API with full CRUD operations, input validation, centralised error handling, optional filtering, and a unit test suite — built to production-grade standards.

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✨ Features

• ✅ Create, Read, Update, Delete tasks
• ✅ Mark tasks as completed (with double-completion guard)
• ✅ Filter tasks by completed status or category
• ✅ Sort tasks by createdAt or dueDate
• ✅ Input validation with meaningful error messages
• ✅ Centralised error handling middleware
• ✅ Optional dueDate and category fields
• ✅ MVC architecture with clean separation of concerns
• ✅ Async/await throughout — no callback hell
• ✅ Jest + Supertest unit & integration tests

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🛠 Tech Stack

Layer	Technology
Runtime	Node.js
Framework	Express.js v4
Database	MongoDB (Mongoose)
Environment	dotenv
Testing	Jest + Supertest
Dev Server	Nodemon

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📁 Folder Structure

todo-api/
├── config/
│   └── db.js                 # MongoDB connection logic
├── controllers/
│   └── taskController.js     # Business logic for each route
├── middleware/
│   └── errorMiddleware.js    # 404 handler + global error handler
├── models/
│   └── taskModel.js          # Mongoose schema & model
├── routes/
│   └── taskRoutes.js         # Express Router — maps URLs to controllers
├── tests/
│   └── task.test.js          # Jest + Supertest test suite
├── utils/
│   └── asyncHandler.js       # HOF to wrap async controllers
├── .env                      # Environment variables (git-ignored)
├── .env.example              # Template for environment variables
├── .gitignore
├── package.json
└── server.js                 # App entry point

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⚙️ Setup Instructions

Prerequisites

• Node.js v16 or higher
• MongoDB running locally or a MongoDB Atlas cluster

1. Clone the Repository

git clone https://github.com/your-username/todo-api.git
cd todo-api

2. Install Dependencies

npm install

3. Configure Environment Variables

cp .env.example .env

Open .env and fill in your values:

PORT=5000
MONGO_URI=mongodb://localhost:27017/todo_db
NODE_ENV=development

4. Start the Development Server

npm run dev

The server will start at: http://localhost:5000

5. Start in Production

npm start

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🔑 Environment Variables

Variable	Description	Default
PORT	Port the server listens on	5000
MONGO_URI	Full MongoDB connection string	mongodb://localhost:27017/todo_db
NODE_ENV	Environment: development/production	development

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🔌 API Endpoints

Base URL: http://localhost:5000/api

Method	Endpoint	Description
POST	/tasks	Create a new task
GET	/tasks	Get all tasks (supports filters)
GET	/tasks/:id	Get a single task by ID
PUT	/tasks/:id	Update a task
DELETE	/tasks/:id	Delete a task

Query Parameters (GET /api/tasks)

Param	Type	Description	Example
completed	Boolean	Filter by completion status	?completed=true
category	String	Filter by category	?category=work
sort	String	Sort by field (prefix - for descending)	?sort=-createdAt

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📬 Sample Requests & Responses

➕ Create a Task

Request

POST /api/tasks
Content-Type: application/json

{
  "title": "Complete internship assignment",
  "description": "Build a Node.js REST API with MVC architecture",
  "dueDate": "2025-07-01",
  "category": "work"
}

Response 201 Created

{
  "success": true,
  "data": {
    "_id": "6651abc123def456789gh012",
    "title": "Complete internship assignment",
    "description": "Build a Node.js REST API with MVC architecture",
    "completed": false,
    "dueDate": "2025-07-01T00:00:00.000Z",
    "category": "work",
    "createdAt": "2025-06-01T10:00:00.000Z",
    "updatedAt": "2025-06-01T10:00:00.000Z"
  }
}

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📋 Get All Tasks

Request

GET /api/tasks

Response 200 OK

{
  "success": true,
  "count": 2,
  "data": [
    {
      "_id": "6651abc123def456789gh012",
      "title": "Complete internship assignment",
      "completed": false,
      "category": "work",
      "createdAt": "2025-06-01T10:00:00.000Z"
    },
    {
      "_id": "6651abc123def456789gh013",
      "title": "Buy groceries",
      "completed": true,
      "category": "personal",
      "createdAt": "2025-05-31T08:30:00.000Z"
    }
  ]
}

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🔍 Get Tasks with Filters

GET /api/tasks?completed=false&category=work&sort=-createdAt

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✏️ Update a Task

Request

PUT /api/tasks/6651abc123def456789gh012
Content-Type: application/json

{
  "completed": true
}

Response 200 OK

{
  "success": true,
  "data": {
    "_id": "6651abc123def456789gh012",
    "title": "Complete internship assignment",
    "completed": true,
    "updatedAt": "2025-06-02T14:30:00.000Z"
  }
}

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❌ Already Completed Error (Business Rule)

Request

PUT /api/tasks/6651abc123def456789gh012
Content-Type: application/json

{
  "completed": true
}

Response 400 Bad Request

{
  "success": false,
  "message": "Task is already marked as completed"
}

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🗑️ Delete a Task

Request

DELETE /api/tasks/6651abc123def456789gh012

Response 200 OK

{
  "success": true,
  "message": "Task \"Complete internship assignment\" deleted successfully",
  "data": {
    "id": "6651abc123def456789gh012"
  }
}

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⚠️ Validation Error (Missing Title)

{
  "success": false,
  "message": "Task title is required and cannot be empty"
}

⚠️ Not Found Error

{
  "success": false,
  "message": "Task not found with ID: 6651abc123def456789gh012"
}

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🧪 Running Tests

npm test

This runs the full Jest + Supertest test suite with coverage reporting.

For a test-specific MongoDB database, add to .env:

MONGO_URI_TEST=mongodb://localhost:27017/todo_test_db

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🏗 Code Architecture & Key Decisions

MVC Pattern

Layer	File	Responsibility
Model	models/taskModel.js	Schema definition, DB interaction
View	JSON responses (API)	Structured JSON output
Controller	controllers/taskController.js	Business logic, input validation
Router	routes/taskRoutes.js	Maps HTTP verbs to controller methods

Why asyncHandler?

Without it, an unhandled async error hangs the request indefinitely. This utility wraps every controller so any rejected Promise is automatically forwarded to Express's error pipeline — eliminating repetitive try/catch blocks.

Why centralised error middleware?

All error formatting lives in one place. Controllers simply throw or set res.status() and throw. This ensures 100% consistent error response shapes across the entire API.

Why runValidators: true on update?

By default, Mongoose skips schema validators on findByIdAndUpdate. Enabling this ensures constraints like maxlength and enum are enforced on edits, not just on creation.

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🚀 Future Improvements

• JWT authentication & user accounts
• Pagination for large task lists (?page=1&limit=10)
• Task priority levels (low / medium / high)
• Search tasks by keyword in title/description
• Rate limiting (express-rate-limit)
• Swagger/OpenAPI documentation
• Docker containerisation
• CI/CD pipeline with GitHub Actions
• In-memory MongoDB (mongodb-memory-server) for isolated testing

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📄 License

MIT © 2025