# Background Tasks { #background-tasks }

You can define background tasks to be run *after* returning a response.

This is useful for operations that need to happen after a request, but that the client doesn't really have to be waiting for the operation to complete before receiving the response.

This includes, for example:

* Email notifications sent after performing an action:

Je hoeft niet langer de verkeerde keys in te typen, op en neer te gaan tussen de documentatie, of heen en weer te scrollen om te checken of je `username` of toch `user_name` had gebruikt.

### Kort

  }

  @Override
  public Collection<V> values() {
    return delegate.values();
  }

  @CanIgnoreReturnValue
  private <T> T checkValid(T t) {
    // a ClassCastException is what's supposed to happen!
    @SuppressWarnings("unchecked")
    K k = (K) t;
    int unused = comparator().compare(k, k);
    return t;
  }

  @Override
  public boolean equals(@Nullable Object obj) {

          @Override
          public void run() {
            do {
              // We can't have a GOLDEN_NOT_PRESENT_KEY because false positives are
              // possible! It's false negatives that can't happen.
              assertThat(bloomFilter.mightContain(GOLDEN_PRESENT_KEY)).isTrue();

              int key = getNonGoldenRandomKey();
              // We can't check that the key is mightContain() == false before the

                }
            }
            // For MSAL4J, if silent refresh fails, return true if token is still valid
            // Actual refresh will happen during next authentication request
            return true;
        }

        /**
         * Gets the Azure AD authentication result.
         * @return The authentication result.
         */

   * cached value, which will be recalculated when {@code get()} is called on the reserialized
   * instance. The actual memoization does not happen when the underlying delegate throws an
   * exception.
   *
   * <p>When the underlying delegate throws an exception then this memoizing supplier will keep
   * delegating calls until it returns valid data.
   *

Sie können beispielsweise kein Pydantic-Modell in eine `JSONResponse` einfügen, ohne es zuvor in ein `dict` zu konvertieren, bei dem alle Datentypen (wie `datetime`, `UUID`, usw.) in JSON-kompatible Typen konvertiert wurden.

In diesen Fällen können Sie den `jsonable_encoder` verwenden, um Ihre Daten zu konvertieren, bevor Sie sie an eine Response übergeben:

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

	}

	// There is no way to handle errors here, so we panic the current goroutine
	// and the Metrics API handler returns a 500 HTTP status code. This should
	// normally not happen, and usually indicates a bug.
	logger.CriticalIf(GlobalContext, errors.Wrap(err, "failed to get metrics"))

	promMetrics := metricValues.ToPromMetrics(mg.CollectorPath.metricPrefix(),
		mg.ExtraLabels)

        SmbTreeConnectionTrace wrapper = new SmbTreeConnectionTrace(delegate);
        wrapper.acquire();
        wrapper.release();

        // Assert: delegate interactions occur when usage transitions happen
        verify(delegate, times(1)).acquire();
        verify(delegate, times(1)).release();
    }

    @Test
    @DisplayName("finalize() invokes checkRelease exactly once")

Und Sie können alle Modelle und Daten für die Sicherheitsanforderungen verwenden (in diesem Fall ein Pydantic-Modell `User`).

Sie sind jedoch nicht auf die Verwendung von bestimmten Datenmodellen, Klassen, oder Typen beschränkt.

Möchten Sie eine `id` und eine `email` und keinen `username` in Ihrem Modell haben? Kein Problem. Sie können dieselben Tools verwenden.