from fastapi import FastAPI, HTTPException

app = FastAPI()

items = {"foo": "The Foo Wrestlers"}


@app.get("/items-header/{item_id}")
async def read_item_header(item_id: str):
    if item_id not in items:
        raise HTTPException(
            status_code=404,
            detail="Item not found",
            headers={"X-Error": "There goes my error"},
        )

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: str | None = Query(
        default=None,
        alias="item-query",
        title="Query string",
        description="Query string for the items to search in the database that have a good match",
        min_length=3,
        max_length=50,
        pattern="^fixedquery$",
        deprecated=True,
    ),
):

    return {"in": "router-decorator-depends"}


app.include_router(router)

client = TestClient(app)


async def overrider_dependency_simple(q: Optional[str] = None):
    return {"q": q, "skip": 5, "limit": 10}


async def overrider_sub_dependency(k: str):
    return {"k": k}


async def overrider_dependency_with_sub(msg: dict = Depends(overrider_sub_dependency)):
    return msg


def test_main_depends():

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: str | None = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")
async def read_items(commons: CommonQueryParams = Depends(CommonQueryParams)):
    response = {}

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: str | None = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")
async def read_items(commons: CommonQueryParams = Depends()):
    response = {}

from datetime import datetime

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Subscription(BaseModel):
    username: str
    monthly_fee: float
    start_date: datetime


@app.webhooks.post("new-subscription")
def new_subscription(body: Subscription):
    """
    When a new user subscribes to your service we'll send you a POST request with this

from fastapi import Depends, FastAPI

app = FastAPI()


async def common_parameters(q: str | None = None, skip: int = 0, limit: int = 100):
    return {"q": q, "skip": skip, "limit": limit}


@app.get("/items/")
async def read_items(commons: dict = Depends(common_parameters)):
    return commons


@app.get("/users/")
async def read_users(commons: dict = Depends(common_parameters)):

from docs_src.custom_response.tutorial008_py39 import app

client = TestClient(app)


def test_get(tmp_path: Path):
    file_path: Path = tmp_path / "large-video-file.mp4"
    tutorial008_py39.some_file_path = str(file_path)
    test_content = b"Fake video bytes"
    file_path.write_bytes(test_content)
    response = client.get("/")

from fastapi import FastAPI, Path, Query

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    item_id: Annotated[int, Path(title="The ID of the item to get")],
    q: Annotated[Union[str, None], Query(alias="item-query")] = None,
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})

* 数据转换
* 数据校验
* 自动生成文档

## 特殊的类型和校验

除了普通的单一值类型（如 `str`、`int`、`float` 等）外，你还可以使用从 `str` 继承的更复杂的单一值类型。

要了解所有的可用选项，请查看关于 <a href="https://docs.pydantic.dev/latest/concepts/types/" class="external-link" target="_blank">来自 Pydantic 的外部类型</a> 的文档。你将在下一章节中看到一些示例。

例如，在 `Image` 模型中我们有一个 `url` 字段，我们可以把它声明为 Pydantic 的 `HttpUrl`，而不是 `str`：

{* ../../docs_src/body_nested_models/tutorial005_py310.py hl[2,8] *}