FastAPI code explainers

python

from fastapi import FastAPI, WebSocket, WebSocketDisconnect
 
app = FastAPI()

Building a WebSocket chat with FastAPI

websockets broadcast connection-management

Intermediate 9 steps

python

from enum import Enum
from typing import Annotated
 
from fastapi import FastAPI, Query, Request, status

Custom validation error responses in FastAPI

validation error-handling enums

Intermediate 8 steps

python

from fastapi import Depends, FastAPI, Header, HTTPException, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

Chaining tenant dependencies in FastAPI

dependency injection multi-tenancy authentication

Intermediate 7 steps

python

import gzip
from fastapi import FastAPI, Request, Response
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.types import ASGIApp

Custom gzip middleware in FastAPI

middleware http-compression content-negotiation

Intermediate 9 steps

python

import re
from starlette.datastructures import URL
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.responses import RedirectResponse

URL normalization middleware in FastAPI

middleware http-redirects url-canonicalization

Intermediate 8 steps

python

from fastapi import APIRouter, Depends, HTTPException, status
 
from app.config import settings
from app.dependencies import get_current_user

Gating a FastAPI route behind a feature flag

feature-flags dependency-injection authorization

Intermediate 7 steps

python

import csv
import io
from typing import Annotated

Content negotiation in FastAPI

content-negotiation dependency-injection http-headers

Intermediate 5 steps

python

from decimal import Decimal
from typing import Annotated
 
from fastapi import APIRouter, status

Cross-field order validation in FastAPI

validation pydantic-models decimal-money

Intermediate 7 steps

python

from fastapi import APIRouter, status
from fastapi.responses import JSONResponse
from sqlalchemy import text
from sqlalchemy.exc import SQLAlchemyError

Liveness vs readiness health checks in FastAPI

health-checks dependency-injection async

Intermediate 6 steps

python

from typing import Optional
 
from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel, EmailStr, Field

How PATCH partial updates work in FastAPI

partial-update validation dependency-injection

Intermediate 8 steps

python

from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel
 
from .dependencies import get_current_user, get_project_service

Building a CRUD router with FastAPI

dependency-injection rest-api authentication

Intermediate 6 steps

python

import base64
import json
from typing import Annotated, Optional

Cursor pagination in a FastAPI endpoint

pagination cursor async

Intermediate 9 steps

python

import secrets
 
from fastapi import Depends, FastAPI, HTTPException, Security, status
from fastapi.security import APIKeyHeader

API key authentication as a FastAPI dependency

authentication dependency-injection api-keys

Intermediate 8 steps

python

from datetime import date, timedelta
from typing import Annotated
 
from fastapi import APIRouter, Depends, Query

Validating date ranges with FastAPI dependencies

dependency-injection validation pydantic

Intermediate 6 steps

python

from fastapi import FastAPI, Request, status
from fastapi.encoders import jsonable_encoder
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse

Redacting sensitive fields in FastAPI errors

validation error-handling security

Intermediate 7 steps

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