## レスポンスモデルのエンコーディングパラメータ

レスポンスモデルにはデフォルト値を設定することができます:

```Python hl_lines="11 13 14"
{!../../docs_src/response_model/tutorial004.py!}
```

* `description: str = None`は`None`がデフォルト値です。
* `tax: float = 10.5`は`10.5`がデフォルト値です。
* `tags: List[str] = []` は空のリスト（`[]`）がデフォルト値です。

しかし、実際に保存されていない場合には結果からそれらを省略した方が良いかもしれません。

/**
 * @author shot
 */
public class MimeTypeUtilTest {

    /**
     * @see org.junit.rules.ExpectedException
     */
    @Rule
    public ExpectedException exception = ExpectedException.none();

    /**
     * @throws Exception
     */
    @Test
    public void testGetFromStream() throws Exception {
        final String path = ClassUtil.getPackageName(this.getClass()).replaceAll("\\.", "/") + "/aaa.html";

    public boolean available() {
        final String ssoType = getSsoType();
        if (logger.isDebugEnabled()) {
            logger.debug("sso.type: {}", ssoType);
        }
        return !Constants.NONE.equals(ssoType);
    }

    public LoginCredential getLoginCredential() {
        if (available()) {
            final SsoAuthenticator authenticator = getAuthenticator();
            if (authenticator != null) {

/test/e2e/generated/bindata.go

# This file used by some vendor repos (e.g. github.com/go-openapi/...) to store secret variables and should not be ignored
!\.drone\.sec

/bazel-*
*.pyc

# generated by verify-vendor.sh

        channel = "flakiness-detection",
        extraParameters = "--checks none --rerun --cross-version-only"
    ),
    historical(
        displayName = "Historical Performance Test",
        timeout = 600,
        defaultBaselines = "last",
        channel = "historical",
        extraParameters = "--checks none --cross-version-only"
    ),
    adHoc(
        displayName = "AdHoc Performance Test",

          sink: Buffer,
          byteCount: Long,
        ): Long {
          check(!closed)
          return data.read(sink, byteCount)
        }

        override fun timeout(): Timeout {
          return Timeout.NONE
        }
      }
    return source.buffer().asResponseBody(null, -1)
  }

  private fun newResponse(
    responseBody: ResponseBody,
    code: Int = 200,
    fn: Response.Builder.() -> Unit = {},

		kmsRouter.Methods(http.MethodGet).Path(version + "/key/status").HandlerFunc(gz(httpTraceAll(kmsAPI.KMSKeyStatusHandler)))
	}

	// If none of the routes match add default error handler routes
	kmsRouter.NotFoundHandler = httpTraceAll(errorResponseHandler)
	kmsRouter.MethodNotAllowedHandler = httpTraceAll(methodNotAllowedHandler("KMS"))

            "description": "A very nice Item",
            "price": 35.4,
            "tax": 3.2,
        },
    )
    assert response.status_code == 200


def test_openapi_schema(client: TestClient) -> None:
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},

            "price": 35.4,
            "tax": 3.2,
        },
    )
    assert response.status_code == 200


@needs_py310
def test_openapi_schema(client: TestClient) -> None:
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},

因此，接着上面的 `user_dict` 继续编写如下代码：

```Python
UserInDB(**user_dict)
```

就会生成如下结果：

```Python
UserInDB(
    username="john",
    password="secret",
    email="john.doe@example.com",
    full_name=None,
)
```

或更精准，直接把可能会用到的内容与 `user_dict` 一起使用：

```Python
UserInDB(
    username = user_dict["username"],
    password = user_dict["password"],
    email = user_dict["email"],