![Grafana](https://raw.githubusercontent.com/minio/minio/master/docs/metrics/prometheus/grafana/node/grafana-node.png)

 * {@link MapIteratorCache}, this structure caches values for the two most recently retrieved keys.
 *
 * @author James Sexton
 */
final class MapRetrievalCache<K, V> extends MapIteratorCache<K, V> {
  // See the note about volatile in the superclass.
  private transient volatile @Nullable CacheEntry<K, V> cacheEntry1;
  private transient volatile @Nullable CacheEntry<K, V> cacheEntry2;

  MapRetrievalCache(Map<K, V> backingMap) {

        // When
        String nextName = mockAddress.nextCalledName(mockContext);

        // Then
        assertEquals(expectedNextName, nextName, "Should return next called name");
        // Note: nextCalledName can return null when no more names available
    }

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[9] *}

/// note | Technische Details

`Header` ist eine Schwesterklasse von `Path`, `Query` und `Cookie`. Sie erbt von derselben gemeinsamen `Param`-Elternklasse.

В таких случаях вы можете использовать `jsonable_encoder` для преобразования данных перед передачей их в ответ:

{* ../../docs_src/response_directly/tutorial001.py hl[6:7,21:22] *}

/// note | Технические детали

Вы также можете использовать `from starlette.responses import JSONResponse`.

따라서 데이터가 올바른 유형인지 확인해야 합니다. 예: `JSONResponse`를 반환하는 경우, JSON과 호환되는지 확인하세요.

또한 `response_model`로 걸러져야 할 데이터가 전달되지 않도록 확인하세요.

///

### 추가 정보

/// note | 기술적 세부사항

`from starlette.responses import Response` 또는 `from starlette.responses import JSONResponse`를 사용할 수도 있습니다.

	Class   string // UNIQUE | FULLTEXT | SPATIAL
	Type    string // btree, hash, gist, spgist, gin, and brin
	Where   string
	Comment string
	Option  string        // WITH PARSER parser_name
	Fields  []IndexOption // Note: IndexOption's Field maybe the same
}

type IndexOption struct {
	*Field
	Expression string
	Sort       string // DESC, ASC
	Collate    string
	Length     int
	Priority   int
}

 * ```
 *
 * If any other extension or parameter is specified, then [unknownValues] will be true. Such
 * responses should be refused as their web socket extensions will not be understood.
 *
 * Note that [java.util.zip.Deflater] is hardcoded to use 15 bits (32 KiB) for
 * `client_max_window_bits` and [java.util.zip.Inflater] is hardcoded to use 15 bits (32 KiB) for

This means that you can send only the data that you want to update, leaving the rest intact.

/// note

`PATCH` is less commonly used and known than `PUT`.

And many teams use only `PUT`, even for partial updates.

You are **free** to use them however you want, **FastAPI** doesn't impose any restrictions.

Vous pouvez également déclarer des paramètres body comme étant optionnels, en leur assignant une valeur par défaut à `None` :

{* ../../docs_src/body_multiple_params/tutorial001_an_py310.py hl[18:20] *}

/// note

Notez que, dans ce cas, le paramètre `item` provenant du `Body` est optionnel (sa valeur par défaut est `None`).

///

## Paramètres multiples du body