Start the development server using Uvicorn with the reload flag enabled: uvicorn main:app --reload Use code with caution.
The Ultimate FastAPI Tutorial: Build and Scale Modern Python APIs (PDF Guide)
Create a project directory and install FastAPI and uvicorn (a lightning-fast ASGI server) 1:
If a user visits /users/abc , FastAPI will automatically return a 422 Unprocessable Entity error because abc is not an integer. Query Parameters
FastAPI automatically generates interactive API documentation. Visit http://127.0.0 to explore the . Core Concepts to Cover in a PDF Tutorial fastapi tutorial pdf
: Based on and fully compatible with OpenAPI and JSON Schema . Key Underlying Technologies Starlette : For the web parts. Pydantic : For the data parts. Uvicorn : The lightning-fast ASGI server execution engine. 2. Setting Up Your Environment
This tutorial serves as a comprehensive guide for those looking to master FastAPI, whether you are reading this online or saving it as a PDF for offline study. Introduction to FastAPI
from fastapi import FastAPI, Depends, HTTPException from sqlalchemy.orm import Session import models, schemas, database models.Base.metadata.create_all(bind=database.engine) app = FastAPI() @app.post("/users/", response_model=schemas.UserResponse) def create_user(user: schemas.UserCreate, db: Session = Depends(database.get_db)): db_user = db.query(models.DbUser).filter(models.DbUser.email == user.email).first() if db_user: raise HTTPException(status_code=400, detail="Email already registered") # In production, make sure to hash the password before saving! new_user = models.DbUser(email=user.email, hashed_password=user.password) db.add(new_user) db.commit() db.refresh(new_user) return new_user Use code with caution. 10. Best Practices for Production Deployment
Extremely high performance, powered by Starlette and Pydantic. Fast to Code: Increases speed of development by about Fewer Bugs: Reduces human-induced errors by about Intuitive: Great editor support (autocomplete everywhere). Start the development server using Uvicorn with the
If you visit /users/1?details=true , FastAPI parses true into Python's boolean True . 6. Request Body and Data Handling with Pydantic
: Navigate to http://127.0.0 to interactively test your API endpoints directly from your browser.
FastAPI automatically enforces data validation. If a user navigates to /items/abc , the API instantly rejects the request with a detailed JSON error, because abc is not an integer. Query Parameters
Several PDF-based tutorials and comprehensive guides are available for FastAPI, ranging from basic introductory slides to advanced e-books. Visit http://127
Studying on the go without an internet connection.
: Turn off the --reload flag in production environments to maximize server speed.
from fastapi import Depends, FastAPI, Header, HTTPException app = FastAPI() # Dependency function async def verify_token(x_token: str = Header(...)): if x_token != "super-secret-token": raise HTTPException(status_code=400, detail="X-Token header invalid") return x_token @app.get("/protected-route/") def read_protected_data(token: str = Depends(verify_token)): return "message": "You have access!", "token_used": token Use code with caution. 9. Connecting to a Database (SQLAlchemy)