errors in your code.

    Read more about it in the
    [FastAPI docs for Handling Errors](https://fastapi.tiangolo.com/tutorial/handling-errors/).

    ## Example

    ```python
    from fastapi import FastAPI, HTTPException

    app = FastAPI()

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


    @app.get("/items/{item_id}")
    async def read_item(item_id: str):

# 高级用户指南

## 额外特性

主要的教程 [教程 - 用户指南](../tutorial/index.md){.internal-link target=_blank} 应该足以让你了解 **FastAPI** 的所有主要特性。

你会在接下来的章节中了解到其他的选项、配置以及额外的特性。

/// tip

接下来的章节**并不一定是**「高级的」。

而且对于你的使用场景来说，解决方案很可能就在其中。

///

## 先阅读教程

你可能仍会用到 **FastAPI** 主教程 [教程 - 用户指南](../tutorial/index.md){.internal-link target=_blank} 中的大多数特性。

import importlib
import runpy
import sys
import unittest

import pytest
from fastapi.testclient import TestClient

MOD_NAME = "docs_src.debugging.tutorial001_py39"


@pytest.fixture(name="client")
def get_client():
    mod = importlib.import_module(MOD_NAME)
    client = TestClient(mod.app)
    return client


def test_uvicorn_run_is_not_called_on_import():
    if sys.modules.get(MOD_NAME):

import importlib
from types import ModuleType

import pytest
from fastapi.exceptions import FastAPIError
from fastapi.testclient import TestClient


@pytest.fixture(
    name="mod",
    params=[
        pytest.param("tutorial008c_py39"),
        pytest.param("tutorial008c_an_py39"),
    ],
)
def get_mod(request: pytest.FixtureRequest):
    mod = importlib.import_module(f"docs_src.dependencies.{request.param}")

    return mod

from fastapi import FastAPI
from fastapi.routing import APIRoute

app = FastAPI()


@app.get("/items/")
async def read_items():
    return [{"item_id": "Foo"}]


def use_route_names_as_operation_ids(app: FastAPI) -> None:
    """
    Simplify operation IDs so that generated API clients have simpler function
    names.

    Should be called only after all routes have been added.
    """
    for route in app.routes:

from fastapi import FastAPI, Security
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from fastapi.testclient import TestClient

app = FastAPI()

security = HTTPBearer()


@app.get("/users/me")
def read_current_user(credentials: HTTPAuthorizationCredentials = Security(security)):
    return {"scheme": credentials.scheme, "credentials": credentials.credentials}


client = TestClient(app)

from fastapi import FastAPI, Security
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from fastapi.testclient import TestClient

app = FastAPI()

security = HTTPBearer(description="HTTP Bearer token scheme")


@app.get("/users/me")
def read_current_user(credentials: HTTPAuthorizationCredentials = Security(security)):
    return {"scheme": credentials.scheme, "credentials": credentials.credentials}

from fastapi import FastAPI, Security
from fastapi.security import HTTPAuthorizationCredentials, HTTPDigest
from fastapi.testclient import TestClient

app = FastAPI()

security = HTTPDigest(description="HTTPDigest scheme")


@app.get("/users/me")
def read_current_user(credentials: HTTPAuthorizationCredentials = Security(security)):
    return {"scheme": credentials.scheme, "credentials": credentials.credentials}


client = TestClient(app)

from fastapi.testclient import TestClient

from docs_src.extending_openapi.tutorial001_py39 import app

client = TestClient(app)


def test():
    response = client.get("/items/")
    assert response.status_code == 200, response.text
    assert response.json() == [{"name": "Foo"}]


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {

```

最后的 `CommonQueryParams`:

```Python
... = Depends(CommonQueryParams)
```

...实际上是 **Fastapi** 用来知道依赖项是什么的。

FastAPI 将从依赖项中提取声明的参数，这才是 FastAPI 实际调用的。

---

在本例中，第一个 `CommonQueryParams` ：

```Python
commons: CommonQueryParams ...
```

...对于 **FastAPI** 没有任何特殊的意义。FastAPI 不会使用它进行数据转换、验证等 (因为对于这，它使用 `= Depends(CommonQueryParams)`)。

你实际上可以只这样编写:

```Python