//// tab | Python 3.9+

```Python hl_lines="79-81"
{!> ../../docs_src/websockets/tutorial003_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="81-83"
{!> ../../docs_src/websockets/tutorial003.py!}
```

////

To try it out:

```Python hl_lines="9"
{!> ../../docs_src/query_params_str_validations/tutorial011.py!}
```

////

//// tab | 🐍 3️⃣.9️⃣ & 🔛

```Python hl_lines="9"
{!> ../../docs_src/query_params_str_validations/tutorial011_py39.py!}
```

////

//// tab | 🐍 3️⃣.1️⃣0️⃣ & 🔛

```Python hl_lines="7"
{!> ../../docs_src/query_params_str_validations/tutorial011_py310.py!}
```

////

⤴️, ⏮️ 📛 💖:

//// tab | Python 3.10+ non-Annotated

/// tip | "Заметка"

Рекомендуется использовать `Annotated` версию, если это возможно.

///

```Python hl_lines="17-19"
{!> ../../docs_src/body_multiple_params/tutorial001_py310.py!}
```

////

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

/// tip | "Заметка"

Рекомендуется использовать версию с `Annotated`, если это возможно.

///

```Python hl_lines="19-21"

```

////

//// tab | Python 3.10+ non-Annotated

/// tip

Préférez utiliser la version `Annotated` si possible.

///

```Python hl_lines="17-19"
{!> ../../docs_src/body_multiple_params/tutorial001_py310.py!}
```

////

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

/// tip

Préférez utiliser la version `Annotated` si possible.

///

```Python hl_lines="19-21"

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture
def client():
    from docs_src.body.tutorial001_py310 import app

    client = TestClient(app)
    return client


@needs_py310
def test_body_float(client: TestClient):
    response = client.post("/items/", json={"name": "Foo", "price": 50.5})

////

//// tab | Python 3.9+ non-Annotated

/// tip

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="9"
{!> ../../docs_src/query_params_str_validations/tutorial011_py39.py!}
```

////

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

/// tip

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="9"

```

////

//// tab | Python 3.10+ non-Annotated

/// tip

尽可能选择使用 `Annotated` 的版本。

///

```Python hl_lines="17-19"
{!> ../../docs_src/body_multiple_params/tutorial001_py310.py!}
```

////

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

/// tip

尽可能选择使用 `Annotated` 的版本。

///

```Python hl_lines="19-21"
{!> ../../docs_src/body_multiple_params/tutorial001.py!}

You can declare `examples` for a Pydantic model that will be added to the generated JSON Schema.

//// tab | Python 3.10+ Pydantic v2

```Python hl_lines="13-24"
{!> ../../docs_src/schema_extra_example/tutorial001_py310.py!}
```

////

//// tab | Python 3.10+ Pydantic v1

```Python hl_lines="13-23"
{!> ../../docs_src/schema_extra_example/tutorial001_py310_pv1.py!}
```

////

//// tab | Python 3.9+ без Annotated

/// tip | "Подсказка"

Рекомендуется использовать версию с `Annotated` если возможно.

///

```Python hl_lines="9"
{!> ../../docs_src/query_params_str_validations/tutorial011_py39.py!}
```

////

//// tab | Python 3.8+ без Annotated

/// tip | "Подсказка"

Рекомендуется использовать версию с `Annotated` если возможно.

///

```Python hl_lines="9"

# 查询参数和字符串校验

**FastAPI** 允许你为参数声明额外的信息和校验。

让我们以下面的应用程序为例：

//// tab | Python 3.10+

```Python hl_lines="7"
{!> ../../docs_src/query_params_str_validations/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="9"
{!> ../../docs_src/query_params_str_validations/tutorial001.py!}
```

////

查询参数 `q` 的类型为 `str`，默认值为 `None`，因此它是可选的。

## 额外的校验