FASTAPI / OVERVIEW

FastAPI — The Full Map

Modern, fast, async Python web framework — from zero to production

EXPLANATION

FastAPI is a modern Python web framework built on top of Starlette (ASGI) and Pydantic. It is one of the fastest Python frameworks available — on par with NodeJS and Go — because it runs asynchronously using Python's async/await system.

What makes FastAPI special:
• Automatic interactive docs (Swagger UI at /docs, ReDoc at /redoc) — generated from your code, zero config
• Type safety everywhere — Python type hints drive validation, serialization, and docs
• Async by default — non-blocking I/O, handles thousands of concurrent requests
• Pydantic integration — all request/response validation is automatic
• Dependency Injection — clean, testable architecture built in

The mental model:
• You write Python functions (sync or async) decorated with HTTP method + path
• FastAPI reads your type hints → validates incoming data → calls your function → serializes the response
• Everything flows through Pydantic models — no manual validation ever

The full stack we'll cover:
① Path & Query params → ② Request Bodies (Pydantic) → ③ Response Models
④ Dependencies → ⑤ Authentication (JWT) → ⑥ Database (SQLModel)
⑦ Middleware & CORS → ⑧ Background Tasks → ⑨ Testing → ⑩ Full Project (TaskFlow)

ARCHITECTURE

┌─────────────────────────────────────────────────────────────┐
  │                    REQUEST LIFECYCLE                        │
  │                                                             │
  │  Client  →  Middleware  →  Router  →  Dependency Injection  │
  │                                            ↓                │
  │                                       Your Function         │
  │                                            ↓                │
  │                                    Pydantic Validation      │
  │                                            ↓                │
  │  Client  ←  JSON Response  ←  Response Model Serialization  │
  └─────────────────────────────────────────────────────────────┘

  TECH STACK:
  FastAPI (framework)
    └── Starlette (ASGI toolkit — routing, middleware, WebSockets)
          └── Uvicorn (ASGI server — runs the event loop)
  Pydantic v2 (validation, serialization — written in Rust, very fast)
  SQLModel (database ORM — Pydantic + SQLAlchemy combined)

CODE

BASH

1# Install FastAPI and all core dependencies
2pip install fastapi uvicorn[standard]
3pip install pydantic sqlmodel
4pip install python-jose[cryptography]  # JWT
5pip install passlib[bcrypt]            # password hashing
6pip install python-multipart           # form data
7pip install httpx pytest               # testing
8
9# Create your first app — hello.py
10# Then run it:
11uvicorn hello:app --reload
12
13# --reload → auto-restart on file changes (dev only)
14# app      → the FastAPI() instance in hello.py
15# Visit:  http://localhost:8000
16# Docs:   http://localhost:8000/docs
17# ReDoc:  http://localhost:8000/redoc

NEXT →1. Routing & Path Params