SaaS Invoicing Application

A comprehensive invoicing solution for businesses built with FastAPI and SQLite.

Features

• User Authentication: JWT-based authentication system
• Client Management: Create, read, update, and delete clients
• Invoice Management: Full CRUD operations for invoices with line items
• Health Monitoring: Built-in health check endpoint
• API Documentation: Interactive API docs with Swagger UI

Tech Stack

• Backend: FastAPI
• Database: SQLite with SQLAlchemy ORM
• Authentication: JWT tokens with bcrypt password hashing
• Migrations: Alembic
• Code Quality: Ruff for linting and formatting

Project Structure

├── main.py                 # FastAPI application entry point
├── requirements.txt        # Python dependencies
├── alembic.ini            # Alembic configuration
├── migrations/            # Database migrations
├── app/
│   ├── core/              # Core functionality (auth, config)
│   ├── db/                # Database configuration
│   ├── models/            # SQLAlchemy models
│   ├── routers/           # API route handlers
│   └── schemas/           # Pydantic schemas

Installation

1. Install dependencies:

pip install -r requirements.txt

2. Set up environment variables:

export SECRET_KEY="your-secret-key-here"

3. Run database migrations:

alembic upgrade head

4. Start the application:

uvicorn main:app --reload

Environment Variables

• SECRET_KEY: JWT secret key for token signing (required)

API Endpoints

Authentication

• POST /auth/login - User login

Users

• POST /users/register - Register new user
• GET /users/me - Get current user profile

Clients

• POST /clients/ - Create new client
• GET /clients/ - List all clients
• GET /clients/{id} - Get specific client
• PUT /clients/{id} - Update client
• DELETE /clients/{id} - Delete client

Invoices

• POST /invoices/ - Create new invoice
• GET /invoices/ - List all invoices
• GET /invoices/{id} - Get specific invoice
• PUT /invoices/{id} - Update invoice
• DELETE /invoices/{id} - Delete invoice

Health

• GET /health - Application health check

API Documentation

Once the application is running, you can access:

• Interactive API docs: http://localhost:8000/docs
• ReDoc documentation: http://localhost:8000/redoc
• OpenAPI JSON: http://localhost:8000/openapi.json

Database

The application uses SQLite database stored at /app/storage/db/db.sqlite. The database includes tables for:

• Users (authentication and profile data)
• Clients (customer information)
• Invoices (invoice headers)
• Invoice Items (line items for invoices)

Development

Code Quality

# Run linting and formatting
ruff check .
ruff format .

Database Migrations

# Create new migration
alembic revision --autogenerate -m "Description"

# Apply migrations
alembic upgrade head

Usage Example

1. Register a new user:

curl -X POST "http://localhost:8000/users/register" \
  -H "Content-Type: application/json" \
  -d '{
    "email": "user@example.com",
    "password": "password123",
    "full_name": "John Doe",
    "company_name": "ACME Corp"
  }'

2. Login to get access token:

curl -X POST "http://localhost:8000/auth/login" \
  -H "Content-Type: application/json" \
  -d '{
    "email": "user@example.com",
    "password": "password123"
  }'

3. Create a client (use the token from step 2):

curl -X POST "http://localhost:8000/clients/" \
  -H "Authorization: Bearer YOUR_TOKEN_HERE" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Client Company",
    "email": "client@example.com",
    "phone": "+1234567890",
    "address": "123 Main St, City, State 12345"
  }'

4. Create an invoice:

curl -X POST "http://localhost:8000/invoices/" \
  -H "Authorization: Bearer YOUR_TOKEN_HERE" \
  -H "Content-Type: application/json" \
  -d '{
    "invoice_number": "INV-001",
    "client_id": 1,
    "due_date": "2024-02-01T00:00:00",
    "tax_rate": 8.5,
    "items": [
      {
        "description": "Web Development Services",
        "quantity": 40,
        "unit_price": 75.00
      }
    ]
  }'

License

This project is licensed under the MIT License.