// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package str provides string manipulation utilities.
package str

import (
	"fmt"
	"strings"
	"unicode"
	"unicode/utf8"
)

// StringList flattens its arguments into a single []string.
// Each argument in args must have type string or []string.

    ```

The query parameter `q` is of type `Union[str, None]` (or `str | None` in Python 3.10), that means that it's of type `str` but could also be `None`, and indeed, the default value is `None`, so FastAPI will know it's not required.

!!! note
    FastAPI will know that the value of `q` is not required because of the default value `= None`.

```

由于我们必须用 `Query(default=None)` 替换默认值 `None`，`Query` 的第一个参数同样也是用于定义默认值。

所以：

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

...使得参数可选，等同于：

```Python
q: str = None
```

但是 `Query` 显式地将其声明为查询参数。

然后，我们可以将更多的参数传递给 `Query`。在本例中，适用于字符串的 `max_length` 参数：

```Python
q: Union[str, None] = Query(default=None, max_length=50)
```

将会校验数据，在数据无效时展示清晰的错误信息，并在 OpenAPI 模式的*路径操作*中记录该参​​数。

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

쿼리 매개변수 `q`는 `Optional[str]` 자료형입니다. 즉, `str` 자료형이지만 `None` 역시 될 수 있음을 뜻하고, 실제로 기본값은 `None`이기 때문에 FastAPI는 이 매개변수가 필수가 아니라는 것을 압니다.

!!! note "참고"
    FastAPI는 `q`의 기본값이 `= None`이기 때문에 필수가 아님을 압니다.

    `Optional[str]`에 있는 `Optional`은 FastAPI가 사용하는게 아니지만, 편집기에게 더 나은 지원과 오류 탐지를 제공하게 해줍니다.

## 추가 검증

    {!> ../../../docs_src/query_params_str_validations/tutorial001_py310.py!}
    ```

🔢 🔢 `q` 🆎 `Union[str, None]` (⚖️ `str | None` 🐍 3️⃣.1️⃣0️⃣), 👈 ⛓ 👈 ⚫️ 🆎 `str` ✋️ 💪 `None`, & 👐, 🔢 💲 `None`, FastAPI 🔜 💭 ⚫️ 🚫 ✔.

!!! note
    FastAPI 🔜 💭 👈 💲 `q` 🚫 ✔ ↩️ 🔢 💲 `= None`.

     `Union` `Union[str, None]` 🔜 ✔ 👆 👨‍🎨 🤝 👆 👍 🐕‍🦺 & 🔍 ❌.

## 🌖 🔬

=== "Python 3.10+"

    ```Python
    q: str | None = None
    ```

=== "Python 3.8+"

    ```Python
    q: Union[str, None] = None
    ```

Вот что мы получим, если обернём это в `Annotated`:

=== "Python 3.10+"

    ```Python
    q: Annotated[str | None] = None
    ```

=== "Python 3.8+"

    ```Python
    q: Annotated[Union[str, None]] = None
    ```

    ```

Der Query-Parameter `q` hat den Typ `Union[str, None]` (oder `str | None` in Python 3.10), was bedeutet, er ist entweder ein `str` oder `None`. Der Defaultwert ist `None`, also weiß FastAPI, der Parameter ist nicht erforderlich.

!!! note "Hinweis"
    FastAPI weiß nur dank des definierten Defaultwertes `=None`, dass der Wert von `q` nicht erforderlich ist

package norm

import "unicode/utf8"

type input struct {
	str   string
	bytes []byte
}

func inputBytes(str []byte) input {
	return input{bytes: str}
}

func inputString(str string) input {
	return input{str: str}
}

func (in *input) setBytes(str []byte) {
	in.str = ""
	in.bytes = str
}

func (in *input) setString(str string) {
	in.str = str
	in.bytes = nil
}

def get_openapi(
    *,
    title: str,
    version: str,
    openapi_version: str = "3.1.0",
    summary: Optional[str] = None,
    description: Optional[str] = None,
    routes: Sequence[BaseRoute],
    webhooks: Optional[Sequence[BaseRoute]] = None,
    tags: Optional[List[Dict[str, Any]]] = None,
    servers: Optional[List[Dict[str, Union[str, Any]]]] = None,
    terms_of_service: Optional[str] = None,

    description: Optional[str] = None
    content: Dict[str, MediaType]
    required: Optional[bool] = None


class Link(BaseModelWithConfig):
    operationRef: Optional[str] = None
    operationId: Optional[str] = None
    parameters: Optional[Dict[str, Union[Any, str]]] = None
    requestBody: Optional[Union[Any, str]] = None
    description: Optional[str] = None
    server: Optional[Server] = None