## Необязательные параметры

Аналогично, вы можете объявлять необязательные query-параметры, установив их значение по умолчанию, равное `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!}
```

////

## Create `main.py`

Copy the example in a file `main.py`:

//// tab | Python 3.9+

```Python
{!> ../../docs_src/security/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python
{!> ../../docs_src/security/tutorial001_an.py!}
```

////

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

/// tip

Prefer to use the `Annotated` version if possible.

///

//// tab | Python 3.10+

```Python hl_lines="26-27  30"
{!> ../../docs_src/dependency_testing/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="28-29  32"
{!> ../../docs_src/dependency_testing/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="29-30  33"

//// tab | Python 3.10+

```Python hl_lines="26-27  30"
{!> ../../docs_src/dependency_testing/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="28-29  32"
{!> ../../docs_src/dependency_testing/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="29-30  33"

Dit betekent ook dat je in Python 3.10 `EenType | None` kunt gebruiken:

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="1  4"
{!> ../../docs_src/python_types/tutorial009.py!}
```

////

//// tab | Python 3.8+ alternative

```Python hl_lines="1  4"

* `Path`
* `Query`

它们的工作方式与其他 FastAPI 端点/ *路径操作* 相同：

//// tab | Python 3.10+

```Python hl_lines="68-69  82"
{!> ../../docs_src/websockets/tutorial002_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="68-69  82"
{!> ../../docs_src/websockets/tutorial002_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="69-70  83"

//// tab | 🐍 3️⃣.6️⃣ & 🔛

```Python hl_lines="15-23"
{!> ../../docs_src/schema_extra_example/tutorial001.py!}
```

////

//// tab | 🐍 3️⃣.1️⃣0️⃣ & 🔛

```Python hl_lines="13-21"
{!> ../../docs_src/schema_extra_example/tutorial001_py310.py!}
```

////

///

✍ 🚙 🔢 #️⃣ 🔐 👟 ⚪️➡️ 👩‍💻.

& ➕1️⃣ 🚙 ✔ 🚥 📨 🔐 🏏 #️⃣ 🏪.

& ➕1️⃣ 1️⃣ 🔓 & 📨 👩‍💻.

//// tab | 🐍 3️⃣.6️⃣ & 🔛

```Python hl_lines="7  48  55-56  59-60  69-75"
{!> ../../docs_src/security/tutorial004.py!}
```

////

//// tab | 🐍 3️⃣.1️⃣0️⃣ & 🔛

```Python hl_lines="6  47  54-55  58-59  68-74"
{!> ../../docs_src/security/tutorial004_py310.py!}
```

Here's a general idea of how the models could look like with their password fields and the places where they are used:

//// tab | Python 3.10+

```Python hl_lines="7  9  14  20  22  27-28  31-33  38-39"
{!> ../../docs_src/extra_models/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="9  11  16  22  24  29-30  33-35  40-41"
{!> ../../docs_src/extra_models/tutorial001.py!}
```

```

///

## Import `Form`

Import `Form` from `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"
{!> ../../docs_src/request_forms/tutorial001_an.py!}
```

////

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

/// tip