from typing import Union

from fastapi import FastAPI, Path
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int = Path(title="The ID of the item to get", ge=0, le=1000),
    q: Union[str, None] = None,

from typing import Any, Union

from fastapi import Depends, FastAPI
from typing_extensions import Annotated

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: Union[str, None] = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")

from typing import Union

from fastapi import Depends, FastAPI
from typing_extensions import Annotated

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: Union[str, None] = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")

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":

from typing import List

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class RecursiveItem(BaseModel):
    sub_items: List["RecursiveItem"] = []
    name: str


RecursiveItem.model_rebuild()


class RecursiveSubitemInSubmodel(BaseModel):
    sub_items2: List["RecursiveItemViaSubmodel"] = []
    name: str


class RecursiveItemViaSubmodel(BaseModel):

    title: Simplify Full Stack Development with FastAPI & MongoDB
    img: https://fastapi.tiangolo.com/img/sponsors/mongodb.png
  - url: https://zuplo.link/fastapi-gh
    title: 'Zuplo: Scale, Protect, Document, and Monetize your FastAPI'
    img: https://fastapi.tiangolo.com/img/sponsors/zuplo.png
  - url: https://liblab.com?utm_source=fastapi

from typing import Union

from fastapi import BackgroundTasks, Depends, FastAPI
from typing_extensions import Annotated

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: Union[str, None] = None):
    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()


class UserBase(BaseModel):
    username: str
    email: EmailStr
    full_name: Union[str, None] = None


class UserIn(UserBase):
    password: str


class UserOut(UserBase):
    pass


class UserInDB(UserBase):
    hashed_password: str


def fake_password_hasher(raw_password: str):

この場合、HTTPヘッダー `Content-Type` には `application/json` がセットされます。

そして、OpenAPIにはそのようにドキュメントされます。

///

/// tip | "豆知識"

`ORJSONResponse` は、現在はFastAPIのみで利用可能で、Starletteでは利用できません。

///

## HTMLレスポンス

**FastAPI** からHTMLを直接返す場合は、`HTMLResponse` を使います。

* `HTMLResponse` をインポートする。
* *path operation* のパラメータ `content_type` に `HTMLResponse` を渡す。

```Python hl_lines="2  7"

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float = 10.5


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The Bar fighters", "price": 62, "tax": 20.2},
    "baz": {
        "name": "Baz",
        "description": "There goes my baz",