# 쿼리 매개변수와 문자열 검증 { #query-parameters-and-string-validations }

**FastAPI**를 사용하면 매개변수에 대한 추가 정보 및 검증을 선언할 수 있습니다.

이 애플리케이션을 예로 들어보겠습니다:

{* ../../docs_src/query_params_str_validations/tutorial001_py310.py hl[7] *}

쿼리 매개변수 `q`는 `str | None` 자료형입니다. 즉, `str` 자료형이지만 `None` 역시 될 수 있음을 뜻하고, 실제로 기본값은 `None`이기 때문에 FastAPI는 이 매개변수가 필수가 아니라는 것을 압니다.

/// note | 참고

FastAPI는 `q`의 기본값이 `= None`이기 때문에 필수가 아님을 압니다.

        // Should not throw NPE during construction
        SmbTreeHandleImpl handleWithNullLoc = new SmbTreeHandleImpl(null, freshConnection);
        assertNotNull(handleWithNullLoc);

        // But operations that use resourceLoc might fail
        // For example, send methods would likely throw NPE when trying to use the null resourceLoc
    }

from your test's `tearDown()`.

### API

#### MockResponse

Mock responses default to an empty response body and a `200` status code.
You can set a custom body with a string, input stream or byte array. Also
add headers with a fluent builder API.

### Java
```java
MockResponse response = new MockResponse.Builder()
    .addHeader("Content-Type", "application/json; charset=utf-8")

    checkPositionIndexes(off, off + len, input.length);
    return HashCode.fromLong(fingerprint(input, off, len));
  }

  @Override
  public int bits() {
    return 64;
  }

  @Override
  public String toString() {
    return "Hashing.farmHashFingerprint64()";
  }

  // End of public functions.

  @VisibleForTesting
  static long fingerprint(byte[] bytes, int offset, int length) {
    if (length <= 32) {

{* ../../docs_src/body_nested_models/tutorial002_py310.py hl[12] *}

## Set types { #set-types }

But then we think about it, and realize that tags shouldn't repeat, they would probably be unique strings.

And Python has a special data type for sets of unique items, the `set`.

Then we can declare `tags` as a set of strings:

      <span style="background-color:#007166"><font color="#D3D7CF"> app </font></span>  Using import string: <font color="#3465A4">main:app</font>

            return ni != null && ni.supportsMulticast();
        } catch (SocketException e) {
            return false;
        }
    }

    @Override
    public String toString() {
        return "NetworkInterfaceInfo{" + "address=" + address + ", linkSpeed=" + linkSpeed + " Mbps" + ", capability=0x"

	metricsCache := newMetricsCache()
	mgMap := make(map[collectorPath]*MetricsGroup)
	bucketMGMap := make(map[collectorPath]*MetricsGroup)
	for _, mg := range allMetricGroups {
		if !strings.HasPrefix(string(mg.CollectorPath), clusterBasePath) {
			mg.AddExtraLabels(
				serverName, globalLocalNodeName,
				// poolIndex, strconv.Itoa(globalLocalPoolIdx),
			)
		}
		mg.SetCache(metricsCache)

	time.Sleep(100 * time.Millisecond)
	ps.Lock()
	if len(ps.subs) != 1 {
		t.Fatal("expected 1 subscriber")
	}
	ps.Unlock()
	close(doneCh2)
}

type maskString string

func (m maskString) Mask() uint64 {
	return 1
}

func TestPubSub(t *testing.T) {
	ps := New[Maskable, Maskable](1)
	ch1 := make(chan Maskable, 1)
	doneCh1 := make(chan struct{})

        return elements;
    }

    /**
     * Returns an array of {@literal String}.
     *
     * @param elements the elements of the array
     * @return the array
     */
    public static String[] asStringArray(final String... elements) {
        return elements;
    }

    /**
     * Returns an array of {@literal Boolean}.
     *