from typing import Optional

from fastapi import FastAPI, Security
from fastapi.security import OAuth2PasswordBearer
from fastapi.testclient import TestClient

app = FastAPI()

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="/token",
    description="OAuth2PasswordBearer security scheme",
    auto_error=False,
)


@app.get("/items/")
async def read_items(token: Optional[str] = Security(oauth2_scheme)):
    if token is None:

from fastapi import Depends, FastAPI, Security
from fastapi.security.open_id_connect_url import OpenIdConnect
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

oid = OpenIdConnect(openIdConnectUrl="/openid")


class User(BaseModel):
    username: str


def get_current_user(oauth_header: str = Security(oid)):
    user = User(username=oauth_header)
    return user

from typing import Union

from fastapi import Body, FastAPI
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,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",

from typing import Annotated

from fastapi import FastAPI, File, UploadFile

app = FastAPI()


@app.post("/files/")
async def create_file(file: Annotated[bytes | None, File()] = None):
    if not file:
        return {"message": "No file sent"}
    else:
        return {"file_size": len(file)}


@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile | None = None):
    if not file:

Aus diesem Grund verwendeten Versionen von FastAPI vor 0.99.0 immer noch Versionen von OpenAPI vor 3.1.0.

///

### Pydantic- und FastAPI-`examples` { #pydantic-and-fastapi-examples }

/// check | 检查

**FastAPI** 使用 Python 类型声明实现了数据校验。

注意，上面的错误清晰地指出了未通过校验的具体原因。

这在开发调试与 API 交互的代码时非常有用。

///

## 查看文档

访问 <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>，查看自动生成的 API 文档：

<img src="/img/tutorial/path-params/image01.png">

/// check | 检查

还是使用 Python 类型声明，**FastAPI** 提供了（集成 Swagger UI 的）API 文档。

注意，路径参数的类型是整数。

from fastapi import FastAPI

tags_metadata = [
    {
        "name": "users",
        "description": "Operations with users. The **login** logic is also here.",
    },
    {
        "name": "items",
        "description": "Manage items. So _fancy_ they have their own docs.",
        "externalDocs": {
            "description": "Items external docs",
            "url": "https://fastapi.tiangolo.com/",
        },
    },
]

Wenn Sie eine ältere FastAPI-App haben, nutzen Sie möglicherweise Pydantic Version 1.

FastAPI Version 0.100.0 unterstützte sowohl Pydantic v1 als auch v2. Es verwendete, was auch immer Sie installiert hatten.

FastAPI Version 0.119.0 führte eine teilweise Unterstützung für Pydantic v1 innerhalb von Pydantic v2 (als `pydantic.v1`) ein, um die Migration zu v2 zu erleichtern.

    * Eğer Starlette'i karşılaştırıyorsanız, Sanic, Flask, Django, vb. frameworkler (veya mikroframeworkler) ile karşılaştırın.
* **FastAPI**:
    * Starlette'in Uvicorn'u kullandığı ve ondan daha hızlı olamayacağı gibi, **FastAPI**'da Starlette'i kullanır, dolayısıyla ondan daha hızlı olamaz.

# Ref: https://github.com/fastapi/fastapi/issues/14454

from typing import Annotated, Optional

from fastapi import APIRouter, Depends, FastAPI, Security
from fastapi.security import OAuth2AuthorizationCodeBearer
from fastapi.testclient import TestClient
from inline_snapshot import snapshot

oauth2_scheme = OAuth2AuthorizationCodeBearer(
    authorizationUrl="authorize",
    tokenUrl="token",
    auto_error=True,