from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = Field(
        default=None, title="The description of the item", max_length=300
    )
    price: float = Field(gt=0, description="The price must be greater than zero")
    tax: Union[float, None] = None


@app.put("/items/{item_id}")

        default=None,
        alias="item-query",
        title="Query string",
        description="Query string for the items to search in the database that have a good match",
        min_length=3,
        max_length=50,
        pattern="^fixedquery$",
        deprecated=True,
    ),
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

= Query(None)
```

그리고 `None`을 사용하여 쿼라 매개변수가 필수적이지 않다는 것을 파악합니다.

`Optional` 부분은 편집기에게 더 나은 지원을 제공하기 위해서만 사용됩니다.

///

또한 `Query`로 더 많은 매개변수를 전달할 수 있습니다. 지금의 경우 문자열에 적용되는 `max_length` 매개변수입니다:

```Python
q: str = Query(None, max_length=50)
```

이는 데이터를 검증할 것이고, 데이터가 유효하지 않다면 명백한 오류를 보여주며, OpenAPI 스키마 *경로 작동*에 매개변수를 문서화 합니다.

## 검증 추가

매개변수 `min_length` 또한 추가할 수 있습니다:

```

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。

`Optional` の部分は、エディターによるより良いサポートを可能にします。

///

そして、さらに多くのパラメータを`Query`に渡すことができます。この場合、文字列に適用される、`max_length`パラメータを指定します。

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

これにより、データを検証し、データが有効でない場合は明確なエラーを表示し、OpenAPIスキーマの　*path operation* にパラメータを記載します。

## バリデーションをさらに追加する

パラメータ`min_length`も追加することができます:

  /**
   * Maximum length of a full domain name, including separators, and leaving room for the root
   * label. See <a href="http://www.ietf.org/rfc/rfc2181.txt">RFC 2181</a> part 11.
   */
  private static final int MAX_LENGTH = 253;

  /**
   * Maximum size of a single part of a domain name. See <a
   * href="http://www.ietf.org/rfc/rfc2181.txt">RFC 2181</a> part 11.
   */
  private static final int MAX_DOMAIN_PART_LENGTH = 63;

                               void* value, size_t max_length,
                               TF_Status* status) {
  const auto* attr = GetAttrValue(oper, attr_name, status);
  if (!status->status.ok()) return;
  if (attr->value_case() != tensorflow::AttrValue::kS) {
    status->status =
        InvalidArgument("Attribute '", attr_name, "' is not a string");
    return;
  }
  if (max_length <= 0) {
    return;
  }

* Update docs for first steps, links and rewording. PR [#1518](https://github.com/tiangolo/fastapi/pull/1518) by [@yankeexe](https://github.com/yankeexe).
* Enable `showCommonExtensions` in Swagger UI to show additional validations like `maxLength`, etc. PR [#1466](https://github.com/tiangolo/fastapi/pull/1466) by [@TiewKH](https://github.com/TiewKH).

    TF_Operation* oper, const char* attr_name, TF_Status* status);

// Fills in `value` with the value of the attribute `attr_name`.  `value` must
// point to an array of length at least `max_length` (ideally set to
// TF_AttrMetadata.total_size from TF_OperationGetAttrMetadata(oper,
// attr_name)).
TF_CAPI_EXPORT extern void TF_OperationGetAttrString(TF_Operation* oper,

        when(mockNdrBuffer.dec_ndr_long()).thenReturn(1, 2);
        // The implementation uses maximum_length/2 for _name_buffers, not length
        when(mockDeferredNdrBuffer.dec_ndr_long()).thenReturn(10, 0, 5); // _name_buffers (max_length/2 = 20/2 = 10), 0, _name_bufferl (5)
        when(mockDeferredNdrBuffer.dec_ndr_short()).thenReturn((int) (short) 'a', (int) (short) 'b', (int) (short) 'c', (int) (short) 'd',
                (int) (short) 'e');