Task Dependency Management System

A Django-based system for managing tasks with support for complex dependencies, automatic status updates, and circular dependency detection.

Tech Stack

• Backend: Django 4.x, Django REST Framework
• Frontend: React 18, Tailwind CSS, Axios
• Database: SQLite (default) / MySQL
• Language: Python 3.x, TypeScript

Frontend Overview

The frontend is a lightweight, single-page application built with React and Tailwind CSS. It features:

• Task List & Form: Intuitive interface for managing tasks and dependencies.
• Graph Visualization: Custom SVG-based graph view with hierarchical layout, zoom, pan, and node highlighting.
• UX Polish: Comprehensive validation, error handling, and loading states for a seamless experience.

Project Status

All tasks from the assignment specification have been fully implemented and verified.

Features

• Task Management: Create, update, and delete tasks with statuses (pending, in_progress, completed, blocked).
• Dependency Management: Define dependencies between tasks with strict validation.
• Circular Dependency Detection: Prevents cycles (e.g., A -> B -> A) using DFS and returns the cycle path.
• Auto Status Updates:
  • Task becomes blocked if any dependency is blocked.
  • Task becomes in_progress (ready) only when all dependencies are completed.
  • Updates propagate recursively to dependent tasks.
• Dependency Visualization: Interactive, hierarchical SVG graph to visualize task relationships.
• Robust UX:
  • Edge-case handling (e.g., impact analysis warning when deleting tasks).
  • Real-time feedback and loading states for all actions.
  • Defensive validation to prevent invalid states (e.g., self-dependencies).

Setup Instructions

1. Clone the repository:

   git clone <repository_url>
   cd "Task Dependency Management System"

2. Create and activate a virtual environment:

   python -m venv venv
   # Windows
   venv\Scripts\activate
   # macOS/Linux
   source venv/bin/activate

3. Install dependencies:

   pip install django djangorestframework django-cors-headers mysqlclient

4. Apply migrations:

   python manage.py migrate

5. Run the server:

   python manage.py runserver

API Endpoints

1. Add Dependency

POST /api/tasks/{task_id}/dependencies/

Adds a dependency where {task_id} depends on the task specified in the body.

Request Body:

{
  "depends_on_id": 5
}

Response (Success - 201):

{
  "status": "Dependency added"
}

Response (Error - Circular Dependency - 400):

{
  "error": "Circular dependency detected",
  "path": [1, 5, 2, 1]
}

2. Update Task Status

PATCH /api/tasks/{task_id}/

Updates a task's status. Triggers automatic status updates for any dependent tasks.

Request Body:

{
  "status": "completed"
}

Response (Success - 200):

{
  "id": 1,
  "title": "Task A",
  "status": "completed",
  ...
}

Testing

Run the unit tests to verify logic:

python manage.py test tasks