from typing import Optional, Union

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

app = FastAPI()


class Item(BaseModel):
    name: Optional[str] = None


class OtherItem(BaseModel):
    price: int


@app.post("/items/")
def save_union_body(item: Union[OtherItem, Item]):
    return {"item": item}


client = TestClient(app)

from typing import Optional

from fastapi import FastAPI
from pydantic import BaseModel, Field
from starlette.testclient import TestClient

app = FastAPI()


class Item(BaseModel):
    name: str = Field(alias="aliased_name")
    price: Optional[float] = None
    owner_ids: Optional[list[int]] = None


@app.get("/items/valid", response_model=Item)
def get_valid():
    return Item(aliased_name="valid", price=1.0)

Obwohl jeder andere normal deklarierte Parameter (z. B. der Body, mit einem Pydantic-Modell) dennoch validiert, konvertiert, annotiert, usw. werden würde.

Es gibt jedoch bestimmte Fälle, in denen es nützlich ist, auf das `Request`-Objekt zuzugreifen.

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


class Model1(BaseModel):
    foo: str
    bar: str


class Model2(BaseModel):
    ref: Model1
    baz: str


class Model3(BaseModel):
    name: str
    age: int
    ref2: Model2


app = FastAPI()


@app.get(
    "/simple_include",
    response_model=Model2,

You can achieve that using <a href="https://docs.pydantic.dev/latest/concepts/validators/#field-after-validator" class="external-link" target="_blank">Pydantic's `AfterValidator`</a> inside of `Annotated`.

/// tip

Pydantic also has <a href="https://docs.pydantic.dev/latest/concepts/validators/#field-before-validator" class="external-link" target="_blank">`BeforeValidator`</a> and others. 🤓

///

## **FastAPI** Tarafından Kullanılanlar

### <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a>

Pydantic Python tip belirteçlerine dayanan; veri doğrulama, veri dönüştürme ve dökümantasyon tanımlamak (JSON Şema kullanarak) için bir kütüphanedir.

import pytest
from fastapi import Depends, FastAPI, Security
from fastapi.security import OAuth2, OAuth2PasswordRequestFormStrict
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

reusable_oauth2 = OAuth2(
    flows={
        "password": {
            "tokenUrl": "token",
            "scopes": {"read:users": "Read the users", "write:users": "Create users"},
        }
    }
)

from typing import Optional

import pytest
from fastapi import Depends, FastAPI, Security
from fastapi.security import OAuth2, OAuth2PasswordRequestFormStrict
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

reusable_oauth2 = OAuth2(
    flows={
        "password": {
            "tokenUrl": "token",
            "scopes": {"read:users": "Read the users", "write:users": "Create users"},
        }

但直接从 `Request` 对象提取数据时（例如，读取请求体），**FastAPI** 不会验证、转换和存档数据（为 API 文档使用 OpenAPI）。

不过，仍可以验证、转换与注释（使用 Pydantic 模型的请求体等）其它正常声明的参数。

但在某些特定情况下，还是需要提取 `Request` 对象。

## 直接使用 `Request` 对象

假设要在*路径操作函数*中获取客户端 IP 地址和主机。

此时，需要直接访问请求。

{* ../../docs_src/using_request_directly/tutorial001.py hl[1,7:8] *}

Embora qualquer outro parâmetro declarado normalmente (o corpo da requisição com um modelo Pydantic, por exemplo) ainda seria validado, convertido, anotado, etc.

Mas há situações específicas onde é útil utilizar o objeto `Request`.

## Utilize o objeto `Request` diretamente { #use-the-request-object-directly }