但本指南会大致展示它们的预期用法。

///

### 使用 Pydantic 的 `exclude_unset` 参数 { #using-pydantics-exclude-unset-parameter }

如果要接收部分更新，建议在 Pydantic 模型的 `.model_dump()` 中使用 `exclude_unset` 参数。

比如，`item.model_dump(exclude_unset=True)`。

这会生成一个 `dict`，只包含创建 `item` 模型时显式设置的数据，不包含默认值。

然后再用它生成一个只含已设置（在请求中发送）数据、且省略默认值的 `dict`：

{* ../../docs_src/body_updates/tutorial002_py310.py hl[32] *}

            }
            return entity;
        });
    }

    /**
     * Creates a label/value map item for dropdowns or list displays.
     *
     * @param label the display label for the item
     * @param value the value associated with the item
     * @return a map containing the label and value entries
     */

      "input": null
    }
  ]
}
```

`needy` は必須のパラメータなので、URLにセットする必要があります:

```
http://127.0.0.1:8000/items/foo-item?needy=sooooneedy
```

...これはうまくいくでしょう:

```JSON
{
    "item_id": "foo-item",
    "needy": "sooooneedy"
}
```

そして当然、あるパラメータを必須に、あるパラメータにデフォルト値を設定し、またあるパラメータを完全にオプショナルにできます:

{* ../../docs_src/query_params/tutorial006_py310.py hl[8] *}

 * for document data. This class wraps an existing map and provides custom behavior
 * for the entrySet method to ensure language fields appear first in iteration order.
 * Used throughout the Fess search system for document data manipulation.
 *
 */
public class DocMap implements Map<String, Object> {

    /** The key used for language field identification */
    private static final String LANG_KEY = "lang";

 */
public class Curl {

    /**
     * The temporary directory used by Curl. It is initialized to the system's temporary directory.
     */
    public static final File tmpDir = new File(System.getProperty("java.io.tmpdir"));

    /**
     * Protected constructor to prevent direct instantiation but allow inheritance.
     */
    protected Curl() {
        // nothing
    }

    /**

    static {
        CANONICAL_PROTOCOLS.put("wsjar", "jar"); // Proprietary protocol used by WebSphere for jar files
        CANONICAL_PROTOCOLS.put("vfsfile", "file"); // Proprietary protocol used by JBossAS5 for file system
    }

    /**
     * Opens a URL and returns an {@link InputStream}.
     *
     * @param url
     *            The URL. Must not be {@literal null}.

            this.systemProperties = new Properties();
            synchronized (
                    systemProperties) { // avoid concurrentmodification if someone else sets/removes an unrelated system
                // property
                this.systemProperties.putAll(systemProperties);
            }
        } else {
            this.systemProperties = null;
        }

        return this;

但本指南會大致示範它們各自的設計用法。

///

### 使用 Pydantic 的 `exclude_unset` 參數 { #using-pydantics-exclude-unset-parameter }

如果要接收部分更新，在 Pydantic 模型的 `.model_dump()` 中使用 `exclude_unset` 參數非常實用。

例如 `item.model_dump(exclude_unset=True)`。

這會產生一個只包含建立 `item` 模型時實際設定過之欄位的 `dict`，不含預設值。

接著你可以用它來生成只包含實際設定（請求中傳來）的資料之 `dict`，省略預設值：

{* ../../docs_src/body_updates/tutorial002_py310.py hl[32] *}

 * <p>This authenticator enables Single Sign-On (SSO) using SAML 2.0 protocol
 * with Identity Providers such as Okta, Azure AD, OneLogin, etc.</p>
 *
 * <h2>Required Configuration</h2>
 * <p>Add the following properties to {@code system.properties}:</p>
 * <pre>
 * # Enable SAML SSO
 * sso.type=saml
 *
 * # Identity Provider settings (obtain from your IdP)
 * saml.idp.entityid=http://www.okta.com/xxxxx

   */
  public static Equivalence<Object> equals() {
    return Equals.INSTANCE;
  }

  /**
   * Returns an equivalence that uses {@code ==} to compare values and {@link
   * System#identityHashCode(Object)} to compute the hash code. {@link Equivalence#equivalent}
   * returns {@code true} if {@code a == b}, including in the case that a and b are both null.
   *
   * @since 13.0