✅ Kanban To-Do List 📋

A simple Spring Boot backend application to manage a To-Do list. It allows you to create, read, update, and delete (CRUD) tasks and lets ChatGPT check your input for spelling errors.

🔗 Check out the follow-up project where I built the frontend for the existing backend: ToDo App Frontend

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🚀 Features

• Create To-Do: Add new tasks with a description and status (OPEN, IN_PROGRESS, DONE)
• Read To-Do: Get all tasks or a specific task by ID
• Update To-Do: Modify a task’s description and status without altering the ID
• Delete To-Do: Remove tasks by ID
• Checks Spelling of POST and PUT requests with ChatGPT 🤖
• Tested using JUnit, Mockito and Integration tests
• Exception Handling via @RestControllerAdvise
• Integrated frontend

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🛠️ Tech Stack

• Java 24
• Spring Boot (Web, Data)
• MongoDB
• Flapdoodle Embedded MongoDB (for integration tests)
• ChatGPT Api (for spelling errors)
• JUnit 5 & Mockito (testing)
• MockMvc (integration testing)
• Lombok
• In-memory repository (or database depending on config)

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🎬 Getting Started

Prerequisites

• Java 24
• Maven

Running the Application

Clone the repository:

git clone
cd todo_backend_project

Build and run:

mvn spring-boot:run

The API will be available at http://localhost:8080/api/todo

To start the api using a mongo-db please set the MONGODB environment variable

mongodb+srv://user:password@host/db

To use the ChatGPT API set the OPENAI_API_Key environment variable

export OPENAI_API_KEY="your_openai_api_key_here"

❓ API Endpoints ❗️

Get all current To-Dos:

GET/api/todo

Add a new To-Do by providing json in body:

POST /api/todo
Request Body:
{ "description": "task description", "status": "OPEN" }

Get a To-Do by ID:

GET /api/todo/{id}

Update an existing To-Do by providing json in body:

PUT /api/todo/{id}
Request Body:
{ "description": "new description", "status": "DONE" }

Delete an existing To-Do by ID:

DELETE /api/todo/{id}

🧪 Testing

Unit tests are implemented for TodoService using Mockito. Integration tests for ToDoController use MockMvc to simulate HTTP requests.

Run tests with:

mvn test

🚦 Exception Handling

This project includes a global exception handling setup using @RestControllerAdvice. Custom exceptions such as NoSuchElementException and IllegalArgumentException are translated into consistent JSON error responses with an errorMessage and a timestamp (instant).

For example:

{
"errorMessage": "No To-Do was found under this id.",
"instant": "2025-09-22T17:46:30.240606Z"
}

This ensures clients receive a clear, structured error message. Unexpected runtime errors are also caught and mapped to proper HTTP status codes (400 for bad requests, 404 for missing data, 500 for internal errors).

💬 Notes

• IDs are generated using a custom IdService.
• Updating a To-Do replaces the old entity in the repository.
• Proper error handling with HTTP status codes:
  • 201 for creation
  • 204 for deletion