from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel, HttpUrl

app = FastAPI()


class Image(BaseModel):
    url: HttpUrl
    name: str


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()
    images: Union[list[Image], None] = None


class Offer(BaseModel):
    name: str

<img src="/img/tutorial/path-params/image02.png">

同様に、互換性のあるツールが多数あります（多くの言語用のコード生成ツールを含む）。

## Pydantic

すべてのデータバリデーションは <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> によって内部で実行されるため、Pydanticの全てのメリットが得られます。そして、安心して利用することができます。

`str`、 `float` 、 `bool` および他の多くの複雑なデータ型を型宣言に使用できます。

これらのいくつかについては、チュートリアルの次の章で説明します。

## 順序の問題

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel
from typing_extensions import Annotated

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,
    item: Annotated[
        Item,
        Body(

from fastapi import Depends, FastAPI
from fastapi.security import OAuth2PasswordBearer
from pydantic import BaseModel

app = FastAPI()

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")


class User(BaseModel):
    username: str
    email: str | None = None
    full_name: str | None = None
    disabled: bool | None = None


def fake_decode_token(token):
    return User(

from typing import Annotated, Union

from fastapi import Body, FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = Field(
        default=None, title="The description of the item", max_length=300
    )
    price: float = Field(gt=0, description="The price must be greater than zero")
    tax: Union[float, None] = None


@app.put("/items/{item_id}")

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()


class UserBase(BaseModel):
    username: str
    email: EmailStr
    full_name: 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):

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class BaseItem(BaseModel):
    description: str
    type: str


class CarItem(BaseItem):
    type: str = "car"


class PlaneItem(BaseItem):
    type: str = "plane"
    size: int


items = {
    "item1": {"description": "All my friends drive a low rider", "type": "car"},
    "item2": {

from typing import List

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


RecursiveItem.update_forward_refs()


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


class RecursiveItemViaSubmodel(BaseModel):

from typing import List

import pytest
from fastapi import FastAPI, UploadFile
from fastapi.datastructures import Default
from fastapi.testclient import TestClient


# TODO: remove when deprecating Pydantic v1
def test_upload_file_invalid():
    with pytest.raises(ValueError):
        UploadFile.validate("not a Starlette UploadFile")


def test_upload_file_invalid_pydantic_v2():
    with pytest.raises(ValueError):

                                    "title": "User-Agent",
                                }
                            )
                            | IsDict(
                                # TODO: remove when deprecating Pydantic v1
                                {"title": "User-Agent", "type": "string"}
                            ),
                            "name": "user-agent",
                            "in": "header",