FastAPI code explainers

python

from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException, status
from pydantic import BaseModel, EmailStr
from sqlalchemy.orm import Session

Building a signup endpoint in FastAPI

dependency-injection request-validation background-tasks

Intermediate 8 steps

python

from functools import wraps
import asyncio
 
from fastapi import APIRouter, FastAPI, Request

Per-route request timeouts in FastAPI

decorators async timeouts

Intermediate 6 steps

python

import asyncio
import json
 
from fastapi import APIRouter, Depends, HTTPException

Streaming export progress with SSE in FastAPI

server-sent-events async-generators streaming

Advanced 8 steps

python

import hashlib
import json
from fastapi import APIRouter, Request, Response, Depends, HTTPException, status

HTTP ETag caching in a FastAPI route

http-caching etag conditional-requests

Intermediate 9 steps

python

from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import Request
from starlette.responses import JSONResponse, Response
from starlette.status import HTTP_413_REQUEST_ENTITY_TOO_LARGE

Enforcing a max request body size in FastAPI

middleware streaming request-limits

Advanced 6 steps

python

import logging
import uuid
from contextvars import ContextVar

Request ID tracing in FastAPI middleware

middleware context-variables request-tracing

Intermediate 7 steps

python

import uuid
from pathlib import Path
 
from fastapi import APIRouter, File, Form, HTTPException, UploadFile

Handling multipart file uploads in FastAPI

file-upload validation multipart-form

Intermediate 6 steps

python

import secrets
from datetime import datetime, timedelta, timezone
 
from fastapi import APIRouter, Cookie, Depends, HTTPException, Response, status

Cookie session auth in FastAPI

session-authentication cookies dependency-injection

Intermediate 8 steps

python

from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from sqlalchemy.orm import Session

Chaining auth dependencies in FastAPI

dependency-injection jwt-authentication authorization

Intermediate 8 steps

python

import pytest
from fastapi.testclient import TestClient
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

Testing FastAPI routes with dependency overrides

testing fixtures dependency-injection

Intermediate 7 steps

python

import json
import hashlib
from datetime import timedelta

Idempotent payment endpoints in FastAPI

idempotency redis distributed-locking

Advanced 9 steps

python

from fastapi import APIRouter, FastAPI, HTTPException
from pydantic import BaseModel

Versioning a FastAPI API with mounted sub-apps

api-versioning response-models sub-applications

Intermediate 6 steps

python

from fastapi import APIRouter, Depends, Response, status
from sqlalchemy.orm import Session
 
from .database import get_db

Building a REST article resource in FastAPI

dependency injection rest api orm

Intermediate 8 steps

python

import asyncio
import logging
from contextlib import asynccontextmanager
from datetime import datetime, timedelta, timezone

A background session cleaner in FastAPI

background-tasks asyncio lifespan

Intermediate 8 steps

python

from datetime import date
from enum import Enum
from typing import Annotated

Reusable query params with Pydantic in FastAPI

query-parameters validation pagination

Intermediate 8 steps

python

import os
from datetime import datetime, timezone
 
import jwt

JWT bearer auth as a FastAPI dependency

authentication jwt dependency-injection

Intermediate 7 steps

python

from datetime import datetime
from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel, ConfigDict, EmailStr
from sqlalchemy.orm import Session

Building a users router in FastAPI

routing serialization dependency-injection

Intermediate 7 steps

python

import shutil
import uuid
from pathlib import Path

Safe avatar uploads in FastAPI

file-upload validation streaming

Intermediate 8 steps