# 查詢參數模型

如果你有一組具有相關性的**查詢參數**，你可以建立一個 **Pydantic 模型**來聲明它們。

這將允許你在**多個地方**去**重複使用模型**，並且一次性為所有參數聲明驗證和元資料 (metadata)。😎

/// note

FastAPI 從 `0.115.0` 版本開始支援這個特性。🤓

///

## 使用 Pydantic 模型的查詢參數

在一個 **Pydantic 模型**中聲明你需要的**查詢參數**，然後將參數聲明為 `Query`：

{* ../../docs_src/query_param_models/tutorial001_an_py310.py hl[9:13,17] *}

**FastAPI** 將會從請求的**查詢參數**中**提取**出**每個欄位**的資料，並將其提供給你定義的 Pydantic 模型。

## 查看文件

		// Note: updates from healEntry to tracker must be sent on results channel.
		healEntry := func(bucket string, entry metaCacheEntry) {
			defer jt.Give()

			if entry.name == "" && len(entry.metadata) == 0 {
				// ignore entries that don't have metadata.
				return
			}
			if entry.isDir() {
				// ignore healing entry.name's with `/` suffix.
				return
			}

			// We might land at .metacache, .trash, .multipart

	Result  struct {
		Credentials auth.Credentials `xml:"Credentials,omitempty"`
	} `xml:"AssumeRoleWithCertificateResult"`
	Metadata struct {
		RequestID string `xml:"RequestId,omitempty"`
	} `xml:"ResponseMetadata,omitempty"`
}

// AssumeRoleWithCustomTokenResponse contains the result of a successful
// AssumeRoleWithCustomToken request.

If you have a group of **cookies** that are related, you can create a **Pydantic model** to declare them. 🍪

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

/// tip

This same technique applies to `Query`, `Cookie`, and `Header`. 😎

///

     *
     * @param artifact         Artifact to be transformed.
     * @param remoteRepository the repository to deploy to
     * @param localRepository  the local repository the metadata is stored in
     */
    void transformForDeployment(
            Artifact artifact, ArtifactRepository remoteRepository, ArtifactRepository localRepository)
            throws ArtifactDeploymentException;

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.repository.metadata;

import org.apache.maven.artifact.ArtifactScopeEnum;
import org.codehaus.plexus.PlexusContainer;
import org.codehaus.plexus.component.repository.exception.ComponentLookupException;

/**

        when(mockChannelManager.getHealthyChannels()).thenReturn(Arrays.asList(channel1, channel2));

        ChannelInfo selected = loadBalancer.selectChannel(queryInfo);
        // Should prefer less loaded channel for metadata operations
        assertEquals(channel1, selected);
    }

    @Test
    void testAffinityBasedStrategy() throws Exception {
        loadBalancer.setStrategy(LoadBalancingStrategy.AFFINITY_BASED);

				}
				if _, nbuf, err := msgp.ReadUint32Bytes(b); err == nil {
					// Read metadata CRC (added in v2, ignore if not found)
					b = nbuf
				}

				hdr, v, err := decodeXLHeaders(v)
				if err != nil {
					return nil, err
				}
				type version struct {
					Idx      int
					Header   json.RawMessage
					Metadata json.RawMessage
				}
				versions := make([]version, hdr.versions)

////

/// tip

You could use the same technique to extend the JSON Schema and add your own custom extra info.

For example you could use it to add metadata for a frontend user interface, etc.

///

/// info

OpenAPI 3.1.0 (used since FastAPI 0.99.0) added support for `examples`, which is part of the **JSON Schema** standard.

// in 'pool.bin', this is eventually used for decommissioning the pool.
func (z *erasureServerPools) Init(ctx context.Context) error {
	// Load rebalance metadata if present
	if err := z.loadRebalanceMeta(ctx); err == nil {
		// Start rebalance routine if we can reload rebalance metadata.
		z.StartRebalance()
	}

	meta := poolMeta{}
	if err := meta.load(ctx, z.serverPools[0], z.serverPools); err != nil {
		return err
	}