# 中间件

你可以向 **FastAPI** 应用添加中间件.

"中间件"是一个函数,它在每个**请求**被特定的*路径操作*处理之前,以及在每个**响应**返回之前工作.

* 它接收你的应用程序的每一个**请求**.
* 然后它可以对这个**请求**做一些事情或者执行任何需要的代码.
* 然后它将**请求**传递给应用程序的其他部分 (通过某种*路径操作*).
* 然后它获取应用程序生产的**响应** (通过某种*路径操作*).
* 它可以对该**响应**做些什么或者执行任何需要的代码.
* 然后它返回这个 **响应**.

/// note | "技术细节"

如果你使用了 `yield` 关键字依赖, 依赖中的退出代码将在执行中间件*后*执行.

如果有任何后台任务(稍后记录), 它们将在执行中间件*后*运行.

///

## 创建中间件

# Подзависимости

Вы можете создавать зависимости, которые имеют **подзависимости**.

Их **вложенность** может быть любой глубины.

**FastAPI** сам займётся их управлением.

## Провайдер зависимости

Можно создать первую зависимость следующим образом:

//// tab | Python 3.10+

```Python hl_lines="8-9"
{!> ../../docs_src/dependencies/tutorial005_an_py310.py!}
```

////

//// tab | Python 3.9+

# Subdependências

Você pode criar dependências que possuem **subdependências**.

Elas podem ter o nível de **profundidade** que você achar necessário.

O **FastAPI** se encarrega de resolver essas dependências.

## Primeira dependência "injetável"

Você pode criar uma primeira dependência (injetável) dessa forma:

//// tab | Python 3.10+

```Python hl_lines="8-9"
{!> ../../docs_src/dependencies/tutorial005_an_py310.py!}
```

# 컨테이너의 FastAPI - 도커

FastAPI 어플리케이션을 배포할 때 일반적인 접근 방법은 **리눅스 컨테이너 이미지**를 생성하는 것입니다. 이 방법은 주로 <a href="https://www.docker.com/" class="external-link" target="_blank">**도커**</a>를 사용해 이루어집니다. 그런 다음 해당 컨테이너 이미지를 몇가지 방법으로 배포할 수 있습니다.

리눅스 컨테이너를 사용하는 데에는 **보안**, **반복 가능성**, **단순함** 등의 장점이 있습니다.

/// tip | "팁"

시간에 쫓기고 있고 이미 이런것들을 알고 있다면 [`Dockerfile`👇](#build-a-docker-image-for-fastapi)로 점프할 수 있습니다.

///

<details>
<summary>도커파일 미리보기 👀</summary>

/// note | "Technical Details"

`Header` is a "sister" class of `Path`, `Query` and `Cookie`. It also inherits from the same common `Param` class.

But remember that when you import `Query`, `Path`, `Header`, and others from `fastapi`, those are actually functions that return special classes.

///

/// info

To declare headers, you need to use `Header`, because otherwise the parameters would be interpreted as query parameters.

///

import os
from pathlib import Path

from fastapi.testclient import TestClient

from docs_src.background_tasks.tutorial002 import app

client = TestClient(app)


def test():
    log = Path("log.txt")
    if log.is_file():
        os.remove(log)  # pragma: no cover
    response = client.post("/send-notification/******@****.***?q=some-query")
    assert response.status_code == 200, response.text

  pull_request_target:
    types:
      - labeled
  workflow_dispatch:

permissions:
  issues: write
  pull-requests: write

jobs:
  issue-manager:
    if: github.repository_owner == 'fastapi'
    runs-on: ubuntu-latest
    steps:
      - name: Dump GitHub context
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"
      - uses: tiangolo/issue-manager@0.5.1

    page.screenshot(path="docs/en/docs/img/tutorial/query-param-models/image01.png")

    # ---------------------
    context.close()
    browser.close()


process = subprocess.Popen(
    ["fastapi", "run", "docs_src/query_param_models/tutorial001.py"]
)
try:
    for _ in range(3):
        try:
            response = httpx.get("http://localhost:8000/docs")
        except httpx.ConnectError:

import pytest
from fastapi.testclient import TestClient

from ...utils import needs_py39


@pytest.fixture(name="client")
def get_client():
    from docs_src.dependencies.tutorial008d_an_py39 import app

    client = TestClient(app)
    return client


@needs_py39
def test_get_no_item(client: TestClient):
    response = client.get("/items/foo")
    assert response.status_code == 404, response.text

/// note | "Detalles Técnicos"

`Cookie` es una clase "hermana" de `Path` y `Query`. También hereda de la misma clase común `Param`.

Pero recuerda que cuando importas `Query`, `Path`, `Cookie`  y otros de `fastapi`, en realidad son funciones que devuelven clases especiales.

///

/// info

Para declarar cookies, necesitas usar `Cookie`, porque de lo contrario los parámetros serían interpretados como parámetros de query.