Um **gerenciador de contexto** em Python é algo que você pode usar em uma declaração `with`, por exemplo, `open()` pode ser usado como um gerenciador de contexto:

```Python
with open("file.txt") as file:
    file.read()
```

Nas versões mais recentes de Python, há também um **gerenciador de contexto assíncrono**. Você o usaria com `async with`:

```Python
async with lifespan(app):
    await do_stuff()
```

      - name: Dump GitHub context
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"
      - uses: actions/checkout@v5
      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.11"
      - name: Setup uv
        uses: astral-sh/setup-uv@v6
        with:
          version: "0.4.15"
          enable-cache: true
          cache-dependency-glob: |

      - name: Dump GitHub context
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"
      - uses: actions/checkout@v5
      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.11"
      - name: Setup uv
        uses: astral-sh/setup-uv@v6
        with:
          version: "0.4.15"
          enable-cache: true
          cache-dependency-glob: |

//// tab | Python 3.8+

```Python hl_lines="1"
async def needy_dependency(fresh_value: Annotated[str, Depends(get_value, use_cache=False)]):
    return {"fresh_value": fresh_value}
```

////

//// tab | Python 3.8+ sin Anotaciones

/// tip | Consejo

Prefiere usar la versión `Annotated` si es posible.

///

```Python hl_lines="1"

//// tab | Python 3.8+

```Python hl_lines="1"
async def needy_dependency(fresh_value: Annotated[str, Depends(get_value, use_cache=False)]):
    return {"fresh_value": fresh_value}
```

////

//// tab | Python 3.8+ nicht annotiert

/// tip | Tipp

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

///

```Python hl_lines="1"

なので:

```Python
q: Optional[str] = Query(default=None)
```

...を以下と同じようにパラメータをオプションにします:

```Python
q: Optional[str] = None
```

しかし、これはクエリパラメータとして明示的に宣言しています。

/// info | 情報

FastAPIは以下の部分を気にすることを覚えておいてください:

```Python
= None
```

もしくは:

```Python
= Query(default=None)
```

そして、 `None` を利用することでクエリパラメータが必須ではないと検知します。

![ReDoc](https://fastapi.tiangolo.com/img/index/index-06-redoc-02.png)


### 現代 Python

這一切都基於標準的 **Python 型別**宣告（感謝 Pydantic）。無需學習新的語法，只需使用標準的現代 Python。

如果你需要 2 分鐘來學習如何使用 Python 型別（即使你不使用 FastAPI），可以看看這個簡短的教學：[Python 型別](python-types.md){.internal-link target=_blank}。

如果你寫帶有 Python 型別的程式碼：

```python
from datetime import date

from pydantic import BaseModel

# 宣告一個變數為 string

And they send a request with a username `johndoe` and a password `love123`.

Then the Python code in your application would be equivalent to something like:

```Python
if "johndoe" == "stanleyjobson" and "love123" == "swordfish":
    ...
```

    steps:
    - name: Dump GitHub context
      env:
        GITHUB_CONTEXT: ${{ toJson(github) }}
      run: echo "$GITHUB_CONTEXT"
    - uses: actions/checkout@v5
    - name: Set up Python
      uses: actions/setup-python@v5
      with:
        python-version: "3.11"
    - name: Setup uv
      uses: astral-sh/setup-uv@v6
      with:
        version: "0.4.15"
        enable-cache: true
        cache-dependency-glob: |

      - name: Dump GitHub context
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"
      - uses: actions/checkout@v5
      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.11"
      - name: Setup uv
        uses: astral-sh/setup-uv@v6
        with:
          version: "0.4.15"
          enable-cache: true
          cache-dependency-glob: |