在 OpenAPI 中，描述這種情況的方式是將該欄位標記為必填，因為它一定存在。

因此，同一個模型的 JSON Schema 會依用於輸入或輸出而不同：

- 用於輸入時，`description` 不是必填
- 用於輸出時，`description` 是必填（且可能為 `None`，在 JSON 中為 `null`）

### 文件中的輸出模型 { #model-for-output-in-docs }

你也可以在文件中檢視輸出模型，`name` 與 `description` 都以紅色星號標示為必填：

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image03.png">
</div>

                        "title": "Message",
                        "required": ["title", "description"],
                        "type": "object",
                        "properties": {
                            "title": {"title": "Title", "type": "string"},
                            "description": {"title": "Description", "type": "string"},
                        },
                    },

                            "title": "InvoiceEvent",
                            "required": ["description", "paid"],
                            "type": "object",
                            "properties": {
                                "description": {
                                    "title": "Description",
                                    "type": "string",
                                },

{* ../../docs_src/separate_openapi_schemas/tutorial001_py310.py ln[1:15] hl[14] *}

...then the `description` field will **not be required**. Because it has a default value of `None`.

### Input Model in Docs { #input-model-in-docs }

You can confirm that in the docs, the `description` field doesn't have a **red asterisk**, it's not marked as required:

<div class="screenshot">

*path operation*'larınıza özet ve açıklama eklemek ve bunları dokümantasyon arayüzünde göstermek için, [Tutorial - Path Operation Configurations - Summary and Description](../tutorial/path-operation-configuration.md#summary-and-description) dokümantasyonunu okuyun.

## Dokümantasyon Response Açıklaması - OpenAPI { #documentation-response-description-openapi }

  <version>0.0.0.0</version>
</parent>
    ]]></configuration>
    <description> This is the MavenProject instance for the parent of the current POM.
    </description>
  </expression>
  <expression>
    <syntax>project.file</syntax>
    <description> This is the File instance that refers to the location of the current POM on
      disk.
    </description>
  </expression>
  <expression>
    <syntax>project.artifacts</syntax>

TFE_MonitoringCounter0* TFE_MonitoringNewCounter0(const char* name,
                                                  TF_Status* status,
                                                  const char* description) {
  auto* result = new TFE_MonitoringCounter0({name, description});
  tsl::Set_TF_Status_from_Status(status, result->counter->GetStatus());
  if (!result->counter->GetStatus().ok()) {
    delete result;
    return nullptr;
  }
  return result;
}

  - type: textarea
    id: current-behavior
    attributes:
      label: Current Behavior
      description: Tell us what happens
    validations:
      required: true
  - type: textarea
    id: expected-behavior
    attributes:
      label: Expected Behavior
      description: Tell us what should happen
    validations:
      required: true
  - type: textarea
    id: context
    attributes:

			Description:    e.Error(),
			HTTPStatusCode: http.StatusBadRequest,
		}
	case AdminError:
		apiErr = APIError{
			Code:           e.Code,
			Description:    e.Message,
			HTTPStatusCode: e.StatusCode,
		}
	case SRError:
		apiErr = errorCodes.ToAPIErrWithErr(e.Code, e.Cause)
	case decomError:
		apiErr = APIError{
			Code:           "XMinioDecommissionNotAllowed",
			Description:    e.Err,

### 输入用的模型 { #model-for-input }

如果你像下面这样把该模型用作输入：

{* ../../docs_src/separate_openapi_schemas/tutorial001_py310.py ln[1:15] hl[14] *}

...那么 `description` 字段将**不是必填项**，因为它的默认值是 `None`。

### 文档中的输入模型 { #input-model-in-docs }

你可以在文档中确认，`description` 字段没有**红色星号**，也就是未被标记为必填：

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image01.png">
</div>

### 输出用的模型 { #model-for-output }