Da mesma forma, você pode declarar parâmetros de consulta opcionais, definindo o valor padrão para `None`:

=== "Python 3.10+"

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

=== "Python 3.8+"

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

Nesse caso, o parâmetro da função `q` será opcional, e `None` será o padrão.

Аналогично, вы можете объявлять необязательные query-параметры, установив их значение по умолчанию, равное `None`:

=== "Python 3.10+"

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

=== "Python 3.8+"

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

    ```Python hl_lines="18-19  26-27"
    {!> ../../../docs_src/dependencies/tutorial008_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="17-18  25-26"
    {!> ../../../docs_src/dependencies/tutorial008_an.py!}
    ```

=== "Python 3.8+ nicht annotiert"

    !!! tip "Tipp"
        Bevorzugen Sie die `Annotated`-Version, falls möglich.

    ```Python hl_lines="16-17  24-25"

👫 💪 **⏬** 👆 💪 👫.

**FastAPI** 🔜 ✊ 💅 🔬 👫.

## 🥇 🔗 "☑"

👆 💪 ✍ 🥇 🔗 ("☑") 💖:

=== "🐍 3️⃣.6️⃣ & 🔛"

    ```Python hl_lines="8-9"
    {!> ../../../docs_src/dependencies/tutorial005.py!}
    ```

=== "🐍 3️⃣.1️⃣0️⃣ & 🔛"

    ```Python hl_lines="6-7"
    {!> ../../../docs_src/dependencies/tutorial005_py310.py!}
    ```

⚫️ 📣 📦 🔢 🔢 `q` `str`, & ⤴️ ⚫️ 📨 ⚫️.

=== "Pydantic v2"

    ```Python hl_lines="17-22  24"
    {!> ../../../docs_src/path_operation_advanced_configuration/tutorial007.py!}
    ```

=== "Pydantic v1"

    ```Python hl_lines="17-22  24"
    {!> ../../../docs_src/path_operation_advanced_configuration/tutorial007_pv1.py!}
    ```

!!! info

你还可以通过将默认值设置为 `None` 来将请求体参数声明为可选参数：

=== "Python 3.10+"

    ```Python hl_lines="18-20"
    {!> ../../../docs_src/body_multiple_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="18-20"
    {!> ../../../docs_src/body_multiple_params/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="19-21"
    {!> ../../../docs_src/body_multiple_params/tutorial001_an.py!}

=== "Python 3.10+"

    ```Python hl_lines="2"
    {!> ../../../docs_src/body/tutorial001_py310.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="4"
    {!> ../../../docs_src/body/tutorial001.py!}
    ```

## 创建数据模型

把数据模型声明为继承 `BaseModel` 的类。

使用 Python 标准类型声明所有属性：

=== "Python 3.10+"

    ```Python hl_lines="5-9"
    {!> ../../../docs_src/body/tutorial001_py310.py!}

=== "Python 3.9+"

    ```Python hl_lines="19"
    {!> ../../../docs_src/dependencies/tutorial006_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="18"
    {!> ../../../docs_src/dependencies/tutorial006_an.py!}
    ```

=== "Python 3.8 без Annotated"

    !!! Подсказка
        Рекомендуется использовать версию с Annotated, если возможно.

    ```Python hl_lines="17"

=== "Python 3.10+"

    ```Python hl_lines="13  15  22  25"
    {!> ../../../docs_src/background_tasks/tutorial002_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="13  15  22  25"
    {!> ../../../docs_src/background_tasks/tutorial002_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="14  16  23  26"

## 导入 `Cookie`

首先，导入 `Cookie`：

=== "Python 3.10+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/cookie_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

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

=== "Python 3.8+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/cookie_params/tutorial001_an.py!}
    ```