from typing import Annotated

from fastapi import BackgroundTasks, Depends, FastAPI

app = FastAPI()


def write_log(message: str):
    with open("log.txt", mode="a") as log:
        log.write(message)


def get_query(background_tasks: BackgroundTasks, q: str | None = None):
    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q

///

## Type hints in **FastAPI** { #type-hints-in-fastapi }

**FastAPI** takes advantage of these type hints to do several things.

With **FastAPI** you declare parameters with type hints and you get:

* **Editor support**.
* **Type checks**.

...and **FastAPI** uses the same declarations to:

from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException

app = FastAPI()


class InternalError(Exception):
    pass


def get_username():
    try:
        yield "Rick"
    except InternalError:
        print("Oops, we didn't raise again, Britney 😱")


@app.get("/items/{item_id}")
def get_item(item_id: str, username: Annotated[str, Depends(get_username)]):
    if item_id == "portal-gun":

import json
from typing import AsyncIterable, Iterable  # noqa: UP035 to test coverage

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel


class Item(BaseModel):
    name: str


app = FastAPI()


@app.get("/items/stream-bare-async")
async def stream_bare_async() -> AsyncIterable:
    yield {"name": "foo"}


@app.get("/items/stream-bare-sync")

import pytest
from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/a", responses={"hello": {"description": "Not a valid additional response"}})
async def a():
    pass  # pragma: no cover


openapi_schema = {
    "openapi": "3.1.0",
    "info": {"title": "FastAPI", "version": "0.1.0"},
    "paths": {
        "/a": {
            "get": {
                "responses": {

from fastapi import APIRouter, FastAPI
from fastapi.testclient import TestClient
from inline_snapshot import snapshot
from pydantic import BaseModel, HttpUrl
from starlette.responses import JSONResponse


class CustomModel(BaseModel):
    a: int


app = FastAPI()

callback_router = APIRouter(default_response_class=JSONResponse)


@callback_router.get(
    "{$callback_url}/callback/", responses={400: {"model": CustomModel}}
)

* 本番アプリケーションで使用されています。

## Starletteの機能 { #starlette-features }

**FastAPI** は [**Starlette**](https://www.starlette.dev/) と完全に互換性があり（かつそれに基づいています）。そのため、手元の Starlette の追加コードも動作します。

`FastAPI` は実際には `Starlette` のサブクラスです。すでに Starlette を知っている、あるいは使っているなら、ほとんどの機能は同じように動作します。

**FastAPI** では **Starlette** のすべての機能が利用できます（FastAPI は強化された Starlette にすぎません）:

/// tip | 提示
整合像 Google、Facebook、X（Twitter）、GitHub 等其他身分驗證/授權提供者也是可行而且相對容易。

最複雜的部分其實是打造一個類似那樣的身分驗證/授權提供者，但 **FastAPI** 提供了工具，能替你處理繁重工作，讓你更輕鬆完成。
///

## **FastAPI** 工具 { #fastapi-utilities }

FastAPI 在 `fastapi.security` 模組中為上述各種安全性方案提供了多種工具，讓這些機制更容易使用。

接下來的章節會示範如何使用這些 **FastAPI** 提供的工具，為你的 API 加入安全性。

from fastapi import Depends, FastAPI, HTTPException

app = FastAPI()


data = {
    "plumbus": {"description": "Freshly pickled plumbus", "owner": "Morty"},
    "portal-gun": {"description": "Gun to create portals", "owner": "Rick"},
}


class OwnerError(Exception):
    pass


def get_username():
    try:
        yield "Rick"
    except OwnerError as e:
        raise HTTPException(status_code=400, detail=f"Owner error: {e}")

from fastapi import FastAPI

description = """
ChimichangApp API helps you do awesome stuff. 🚀

## Items

You can **read items**.

## Users

You will be able to:

* **Create users** (_not implemented_).
* **Read users** (_not implemented_).
"""

app = FastAPI(
    title="ChimichangApp",
    description=description,
    summary="Deadpool's favorite app. Nuff said.",
    version="0.0.1",