Bevorzugen Sie die `Annotated`-Version, falls möglich.

///

```Python hl_lines="10"
{!> ../../docs_src/dependencies/tutorial011.py!}
```

////

In diesem Fall ist dieses `__call__` das, was **FastAPI** verwendet, um nach zusätzlichen Parametern und Unterabhängigkeiten zu suchen, und das ist es auch, was später aufgerufen wird, um einen Wert an den Parameter in Ihrer *Pfadoperation-Funktion* zu übergeben.

from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from pydantic import BaseModel

fake_users_db = {
    "johndoe": {
        "username": "johndoe",
        "full_name": "John Doe",
        "email": "******@****.***",
        "hashed_password": "fakehashedsecret",
        "disabled": False,
    },
    "alice": {

```

</div>

强烈建议你在本地编写或复制代码，对其进行编辑并运行。

在编辑器中使用 FastAPI 会真正地展现出它的优势：只需要编写很少的代码，所有的类型检查，代码补全等等。

---

## 安装 FastAPI

第一个步骤是安装 FastAPI。

为了使用本教程，你可能需要安装所有的可选依赖及对应功能：

<div class="termy">

```console
$ pip install "fastapi[all]"

---> 100%
```

</div>

......以上安装还包括了 `uvicorn`，你可以将其用作运行代码的服务器。

/// note

你也可以分开来安装。

Aqui tem um mini <a href="https://sqlmodel.tiangolo.com/tutorial/fastapi/" class="external-link" target="_blank">tutorial de como usar SQLModel com FastAPI</a>. ✨

from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException

app = FastAPI()


class InternalError(Exception):
    pass


def get_username():
    try:
        yield "Rick"
    except InternalError:
        print("We don't swallow the internal error here, we raise again 😎")
        raise


@app.get("/items/{item_id}")
def get_item(item_id: str, username: Annotated[str, Depends(get_username)]):

from fastapi import Depends, FastAPI, Header, HTTPException
from typing_extensions import Annotated


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")

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: set[str] = set()


@app.post("/items/", response_model=Item, summary="Create an item")
async def create_item(item: Item):
    """
    Create an item with all the information:

    - **name**: each item must have a name

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from ...utils import needs_py39


@pytest.fixture(name="client")
def get_client():
    from docs_src.dependencies.tutorial006_an_py39 import app

    client = TestClient(app)
    return client


@needs_py39
def test_get_no_headers(client: TestClient):
    response = client.get("/items/")
    assert response.status_code == 422, response.text

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from ...utils import needs_py39


@pytest.fixture(name="client")
def get_client():
    from docs_src.schema_extra_example.tutorial004_an_py39 import app

    client = TestClient(app)
    return client


# Test required and embedded body parameters with no bodies sent
@needs_py39
def test_post_body_example(client: TestClient):

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture(name="client")
def get_client():
    from docs_src.schema_extra_example.tutorial004_py310 import app

    client = TestClient(app)
    return client


# Test required and embedded body parameters with no bodies sent
@needs_py310
def test_post_body_example(client: TestClient):