# yieldを持つ依存関係

FastAPIは、いくつかの<abbr title='時々"exit"、"cleanup"、"teardown"、"close"、"context managers"、 ...のように呼ばれる'>終了後の追加のステップ</abbr>を行う依存関係をサポートしています。

これを行うには、`return`の代わりに`yield`を使い、その後に追加のステップを書きます。

/// tip | 豆知識

`yield`は必ず一度だけ使用するようにしてください。

///

/// info | 情報

これを動作させるには、**Python 3.7** 以上を使用するか、**Python 3.6** では"backports"をインストールする必要があります:

```
pip install async-exit-stack async-generator
```

# Abhängigkeiten mit `yield` { #dependencies-with-yield }

FastAPI unterstützt Abhängigkeiten, die nach Abschluss einige <abbr title="Manchmal auch genannt „Exit Code“, „Cleanup Code“, „Teardown Code“, „Closing Code“, „Kontextmanager Exit Code“, usw.">zusätzliche Schritte ausführen</abbr>.

Verwenden Sie dazu `yield` statt `return` und schreiben Sie die zusätzlichen Schritte / den zusätzlichen Code danach.

/// tip | Tipp

      }
      finished = true;
    }

    @Override
    protected HashCode makeHash() {
      if (!finished) {
        // processRemaining does teardown we always want to do -- the folding together of the four
        // rolling CRCs.  So we call it on an empty ByteBuffer if we didn't already.
        processRemaining(EMPTY);
      }
      return HashCode.fromInt(~crc0);

# Dependências com yield { #dependencies-with-yield }

O **FastAPI** possui suporte para dependências que realizam <abbr title='às vezes também chamado de "código de saída", "código de limpeza", "código de teardown", "código de fechamento", "código de saída do gerenciador de contexto", etc.'>alguns passos extras ao finalizar</abbr>.

Para fazer isso, utilize `yield` em vez de `return`, e escreva os passos extras (código) depois.

/// tip | Dica

# Dependencies with yield { #dependencies-with-yield }

FastAPI supports dependencies that do some <abbr title='sometimes also called "exit code", "cleanup code", "teardown code", "closing code", "context manager exit code", etc.'>extra steps after finishing</abbr>.

To do this, use `yield` instead of `return`, and write the extra steps (code) after.

/// tip

Make sure to use `yield` one single time per dependency.

///

/// note | Technical Details

@Tag("Slow")
class MockWebServerTest {
  @RegisterExtension
  var platform = PlatformRule()

  private val server = MockWebServer()

  @BeforeEach
  fun setUp() {
    server.start()
  }

  @AfterEach
  fun tearDown() {
    server.close()
  }

  @Test
  fun defaultMockResponse() {
    val builder = MockResponse.Builder()
    assertThat(headersToList(builder)).containsExactly("Content-Length: 0")

    call =
      clientTestRule.newClient().newCall(
        Request
          .Builder()
          .url("https://$uriHost:$uriPort/")
          .build(),
      ) as RealCall
  }

  @AfterEach fun tearDown() {
    factory.close()
  }

  @Test fun singleRoute() {
    val address = factory.newAddress()
    val routeSelector = newRouteSelector(address)
    assertThat(routeSelector.hasNext()).isTrue()

    return clientTestRule
  }

  @BeforeEach
  fun setUp() {
    platform.assumeNotOpenJSSE()
  }

  @AfterEach
  @Throws(InterruptedException::class)
  fun tearDown() {
    clientListener.assertExhausted()
  }

  @Test
  fun textMessage() {
    webServer.enqueue(
      MockResponse
        .Builder()
        .webSocketUpgrade(serverListener)

    }

    @BeforeEach
    void setUp() throws Exception {
        validator = new DefaultModelValidator(new DefaultModelVersionProcessor());
    }

    @AfterEach
    void tearDown() throws Exception {
        this.validator = null;
    }

    private void assertViolations(SimpleProblemCollector result, int fatals, int errors, int warnings) {

      listener.onClosed(this, code, reason!!)
    }

    readerToClose?.closeQuietly()
  }

  /** For testing: force this web socket to release its threads. */
  @Throws(InterruptedException::class)
  fun tearDown() {
    taskQueue.shutdown()
    taskQueue.idleLatch().await(10, TimeUnit.SECONDS)
  }

  @Synchronized fun sentPingCount(): Int = sentPingCount