FASTAPI_QUICKSTART.md

FastAPI OOP Example - Quick Start Guide

Get the FastAPI example running in under 5 minutes.

Prerequisites

• Python 3.8 or higher
• pip (Python package manager)

Installation

1. Install Dependencies

pip install -r requirements-fastapi.txt

Or install manually:

pip install fastapi uvicorn pydantic[email]

2. Run the Application

python fastapi_oop_example.py

You should see:

╔══════════════════════════════════════════════════════════════════╗
║          Cloud Engineers API - OOP FastAPI Example               ║
╚══════════════════════════════════════════════════════════════════╝

Starting server...
API Documentation: http://localhost:8000/docs
Alternative Docs:  http://localhost:8000/redoc

3. Open Your Browser

Navigate to: http://localhost:8000/docs

You'll see the interactive API documentation (Swagger UI).

Try It Out (Interactive Docs)

1. List All Engineers

1. Click on GET /engineers
2. Click "Try it out"
3. Click "Execute"
4. See the pre-loaded sample data

2. Create a New Engineer

1. Click on POST /engineers
2. Click "Try it out"
3. Edit the request body:

{
  "name": "Your Name",
  "email": "yourname@rockstars.com",
  "specialty": "Cloud Engineering",
  "hourly_rate": 110,
  "certification_level": "mid"
}

4. Click "Execute"
5. See the response with the created engineer

3. Add a Certification

1. Click on POST /engineers/{engineer_id}/certifications
2. Click "Try it out"
3. Enter 1 for engineer_id
4. Edit request body:

{
  "cert_code": "AZ-305",
  "platform": "azure"
}

5. Click "Execute"

4. Find Azure Engineers

1. Click on GET /engineers/platform/{platform}
2. Click "Try it out"
3. Select azure from dropdown
4. Click "Execute"
5. See all engineers with Azure certifications

5. Get Revenue Report

1. Click on GET /reports/revenue
2. Click "Try it out"
3. Click "Execute"
4. See the revenue analysis

Try It Out (Command Line)

List Engineers

curl http://localhost:8000/engineers

Create Engineer

curl -X POST http://localhost:8000/engineers \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Jane Smith",
    "email": "jane@rockstars.com",
    "specialty": "Kubernetes",
    "hourly_rate": 115,
    "certification_level": "senior"
  }'

Get Specific Engineer

curl http://localhost:8000/engineers/1

Update Engineer

curl -X PATCH http://localhost:8000/engineers/1 \
  -H "Content-Type: application/json" \
  -d '{
    "hourly_rate": 125,
    "is_available": false
  }'

Add Certification

curl -X POST http://localhost:8000/engineers/1/certifications \
  -H "Content-Type: application/json" \
  -d '{
    "cert_code": "AZ-500",
    "platform": "azure"
  }'

Find Engineers by Platform

curl http://localhost:8000/engineers/platform/azure

Get Revenue Report

curl http://localhost:8000/reports/revenue

Run Tests

Install Test Dependencies

pip install pytest pytest-asyncio httpx

Run All Tests

pytest test_fastapi_oop.py -v

Run Specific Test Class

pytest test_fastapi_oop.py::TestEngineerDomainModel -v

Run with Coverage

pytest test_fastapi_oop.py --cov=fastapi_oop_example --cov-report=html

Understanding the Code

Key Files

• fastapi_oop_example.py - Main application (800+ lines)
• FASTAPI_README.md - Detailed documentation
• test_fastapi_oop.py - Comprehensive tests

Architecture Overview

API Endpoints (FastAPI)
    ↓
Service Layer (Business Logic)
    ↓
Repository (Data Access)
    ↓
Domain Models (Entities)

Key OOP Concepts Demonstrated

1. Abstraction - IEngineerRepository interface
2. Encapsulation - Business logic in Engineer class
3. Dependency Injection - FastAPI's Depends()
4. Singleton - RepositoryManager
5. Validation - Pydantic models

Common Issues

Port Already in Use

If port 8000 is taken:

# Run on different port
uvicorn fastapi_oop_example:app --port 8001

Import Errors

Make sure you're in the correct directory:

# Should contain fastapi_oop_example.py
ls -la

# Run from this directory
python fastapi_oop_example.py

Missing Dependencies

# Reinstall all dependencies
pip install -r requirements-fastapi.txt --upgrade

Next Steps

1. Read the full documentation: FASTAPI_README.md
2. Study the code: Open fastapi_oop_example.py in your IDE
3. Run the tests: pytest test_fastapi_oop.py -v
4. Modify the example: Add new endpoints or features
5. Learn the patterns: Read about Repository and Service patterns

Learning Path

After mastering this example:

1. Section 400 - Inheritance - Extend the Engineer class
2. Section 600 - Abstraction - More on abstract classes
3. Section 800 - Design Patterns - Patterns used in this example

Resources

• Interactive API Docs: http://localhost:8000/docs
• Alternative Docs: http://localhost:8000/redoc
• FastAPI Tutorial: https://fastapi.tiangolo.com/tutorial/
• Repository Pattern: https://martinfowler.com/eaaCatalog/repository.html

Questions?

The code is heavily commented. Read through:

1. Domain Models section
2. Repository Pattern section
3. Service Layer section
4. Dependency Injection section

Each section has detailed comments explaining the OOP concepts.

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Happy Learning! 🚀

Part of the learning-python-object-oriented repository