//// tab | Python 3.9+

```Python hl_lines="9-11  15"
{!> ../../docs_src/request_form_models/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="8-10  14"
{!> ../../docs_src/request_form_models/tutorial001_an.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip | "Dica"

比如，你可以将请求体的一个 `example` 传递给 `Body`:

//// tab | Python 3.10+

```Python hl_lines="22-27"
{!> ../../docs_src/schema_extra_example/tutorial003_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="22-27"
{!> ../../docs_src/schema_extra_example/tutorial003_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="23-28"

          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"
      - uses: actions/checkout@v4
      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.10"
          # Issue ref: https://github.com/actions/setup-python/issues/436
          # cache: "pip"
          # cache-dependency-path: pyproject.toml
      - name: Install build dependencies

//// tab | Python 3.9+

```Python hl_lines="9"
{!> ../../docs_src/request_forms/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="8"
{!> ../../docs_src/request_forms/tutorial001_an.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="7"

</div>

////

### Lendo variáveis de ambiente com Python

Você também pode criar variáveis de ambiente fora do Python, no terminal (ou com qualquer outro método), e realizar a leitura delas no Python.

Por exemplo, você pode definir um arquivo `main.py` com o seguinte código:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// dica

## Пример

Вот пример *операции пути* с параметрами, который демонстрирует некоторые из вышеперечисленных типов.

//// tab | Python 3.8 и выше

```Python hl_lines="1  3  12-16"
{!> ../../docs_src/extra_data_types/tutorial001.py!}
```

////

//// tab | Python 3.10 и выше

```Python hl_lines="1  2  11-15"
{!> ../../docs_src/extra_data_types/tutorial001_py310.py!}
```

////

它接收一个对象，比如Pydantic模型，并会返回一个JSON兼容的版本：

//// tab | Python 3.10+

```Python hl_lines="4  21"
{!> ../../docs_src/encoder/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="5  22"
{!> ../../docs_src/encoder/tutorial001.py!}
```

////

在这个例子中，它将Pydantic模型转换为`dict`，并将`datetime`转换为`str`。

Z. B. `pip install python-multipart`.

///

## `Form` importieren

Importieren Sie `Form` von `fastapi`:

//// tab | Python 3.9+

```Python hl_lines="3"
{!> ../../docs_src/request_forms/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="1"

## Optional parameters

The same way, you can declare optional query parameters, by setting their default to `None`:

//// tab | Python 3.10+

```Python hl_lines="7"
{!> ../../docs_src/query_params/tutorial002_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="9"
{!> ../../docs_src/query_params/tutorial002.py!}
```

////

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。