`JSONResponse` 本身是一个 `Response` 的子类。

///

当你返回一个 `Response` 时，**FastAPI** 会直接传递它。

**FastAPI** 不会用 Pydantic 模型做任何数据转换，不会将响应内容转换成任何类型，等等。

这种特性给你极大的可扩展性。你可以返回任何数据类型，重写任何数据声明或者校验，等等。

## 在 `Response` 中使用 `jsonable_encoder`

由于 **FastAPI** 并未对你返回的 `Response` 做任何改变，你必须确保你已经准备好响应内容。

例如，如果不首先将 Pydantic 模型转换为 `dict`，并将所有数据类型（如 `datetime`、`UUID` 等）转换为兼容 JSON 的类型，则不能将其放入JSONResponse中。

                                    "title": "Ads Id",
                                }
                            )
                            | IsDict(
                                # TODO: remove when deprecating Pydantic v1
                                {"title": "Ads Id", "type": "string"}
                            ),
                            "name": "ads_id",
                            "in": "cookie",
                        }

import typing

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

app = FastAPI()


class JsonApiResponse(JSONResponse):
    media_type = "application/vnd.api+json"


class Error(BaseModel):
    status: str
    title: str


class JsonApiError(BaseModel):
    errors: typing.List[Error]


@app.get(
    "/a",

from typing import Optional

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

app = FastAPI()


class SubModel(BaseModel):
    a: Optional[str] = "foo"


class Model(BaseModel):
    x: Optional[int] = None
    sub: SubModel


class ModelSubclass(Model):
    y: int
    z: int = 0
    w: Optional[int] = None


class ModelDefaults(BaseModel):

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

                                    "title": "Strange Header",
                                }
                            )
                            | IsDict(
                                # TODO: remove when deprecating Pydantic v1
                                {"title": "Strange Header", "type": "string"}
                            ),
                            "name": "strange_header",
                            "in": "header",

                                    ],
                                }
                            )
                            | IsDict(
                                # TODO: remove when deprecating Pydantic v1
                                {
                                    "title": "X-Token",
                                    "type": "array",
                                    "items": {"type": "string"},

from typing import List, Optional, Union

import pytest
from fastapi import FastAPI
from fastapi.exceptions import ResponseValidationError
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: Optional[float] = None
    owner_ids: Optional[List[int]] = None


@app.get("/items/invalid", response_model=Item)
def get_invalid():

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


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


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

from typing import Annotated, 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


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,