from fastapi import FastAPI
from pydantic import BaseModel


class Item(BaseModel):
    name: str
    description: str | None = None


app = FastAPI(separate_input_output_schemas=False)


@app.post("/items/")
def create_item(item: Item):
    return item


@app.get("/items/")
def read_items() -> list[Item]:
    return [
        Item(
            name="Portal Gun",

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float


class ResponseMessage(BaseModel):
    message: str


@app.post("/items/", response_model=ResponseMessage)
async def create_item(item: Item):
    return {"message": "item received"}


@app.get("/items/", response_model=list[Item])
async def get_items():
    return [

from typing import Annotated, Literal

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

app = FastAPI()


class FilterParams(BaseModel):
    model_config = {"extra": "forbid"}

    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: list[str] = []


@app.get("/items/")

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: list[str] = []


@app.post("/items/")
async def create_item(item: Item) -> Item:
    return item


@app.get("/items/")
async def read_items() -> list[Item]:
    return [

def test_openapi_schema():
    """
    Test that example overrides work:

    * pydantic model schema_extra is included
    * Body(example={}) overrides schema_extra in pydantic model
    * Body(examples{}) overrides Body(example={}) and schema_extra in pydantic model
    """
    app = create_app()
    client = TestClient(app)
    response = client.get("/openapi.json")

from fastapi import FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: str | None = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])


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

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


class Item(BaseModel):
    id: str
    value: str


class Message(BaseModel):
    message: str


app = FastAPI()


@app.get("/items/{item_id}", response_model=Item, responses={404: {"model": Message}})
async def read_item(item_id: str):
    if item_id == "foo":

你可以向你的*路径操作装饰器*传入参数 `responses`。

它接收一个 `dict`：键是每个响应的状态码（例如 `200`），值是包含该响应信息的另一个 `dict`。

这些响应的每个 `dict` 都可以有一个键 `model`，包含一个 Pydantic 模型，就像 `response_model` 一样。

**FastAPI** 会获取该模型，生成它的 JSON Schema，并将其放在 OpenAPI 中的正确位置。

例如，要声明另一个状态码为 `404` 且具有 Pydantic 模型 `Message` 的响应，你可以这样写：

{* ../../docs_src/additional_responses/tutorial001_py310.py hl[18,22] *}

/// note | 注意

记住你需要直接返回 `JSONResponse`。

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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

    model_config = {
        "json_schema_extra": {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,

如果你要回傳的每個 JSON 項目型別都是 `Item`（一個 Pydantic 模型），而且該函式是 async，你可以將回傳型別宣告為 `AsyncIterable[Item]`：

{* ../../docs_src/stream_json_lines/tutorial001_py310.py ln[1:24] hl[9:11,22] *}

如果你宣告了回傳型別，FastAPI 會用它來進行資料的**驗證**、在 OpenAPI 中**文件化**、**過濾**，並使用 Pydantic 進行**序列化**。

/// tip

由於 Pydantic 會在 **Rust** 端進行序列化，宣告回傳型別可獲得比未宣告時高得多的**效能**。

///