# Verwendung von Datenklassen { #using-dataclasses }

FastAPI basiert auf **Pydantic**, und ich habe Ihnen gezeigt, wie Sie Pydantic-Modelle verwenden können, um <abbr title="Request – Anfrage: Daten, die der Client zum Server sendet">Requests</abbr> und <abbr title="Response – Antwort: Daten, die der Server zum anfragenden Client zurücksendet">Responses</abbr> zu deklarieren.

## Other middlewares { #other-middlewares }

There are many other ASGI middlewares.

For example:

import java.util.Iterator;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * This class provides a skeletal implementation of the {@link Multiset} interface. A new multiset
 * implementation can be created easily by extending this class and implementing the {@link
 * Multiset#entrySet()} method, plus optionally overriding {@link #add(Object, int)} and {@link
 * #remove(Object, int)} to enable modifications to the multiset.
 *

    if (seenExceptionsLocal == null) {
      // TODO(cpovirk): Should we use a simpler (presumably cheaper) data structure?
      /*
       * Using weak references here could let us release exceptions earlier, but:
       *
       * 1. On Android, querying a WeakReference blocks if the GC is doing an otherwise-concurrent
       * pass.
       *

Import the `Response` class (sub-class) you want to use and declare it in the *path operation decorator*.

For large responses, returning a `Response` directly is much faster than returning a dictionary.

things you should know about contributing:

1.  API changes require discussion, use cases, etc. Code comes later.
2.  Pull requests are great for small fixes for bugs, documentation, etc.
3.  Pull requests are not merged directly into the master branch.
4.  Code contributions require signing a Google CLA.

API changes
-----------

We make changes to Guava's public [APIs][], including adding new APIs, very

Der `TestClient` basiert auf <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a> und glücklicherweise können wir es direkt verwenden, um die API zu testen.

## Beispiel { #example }

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicInteger;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Basher test for {@link ConcurrentHashMultiset}: start a bunch of threads, have each of them do
 * operations at random. Each thread keeps track of the per-key deltas that it's directly

/**
 * Holds a model along with some auxiliary information. This internal utility class assists the model builder during POM
 * processing by providing a means to transport information that cannot be (easily) extracted from the model itself.
 *
 * @deprecated use {@code org.apache.maven.api.services.ModelBuilder} instead
 */
@Deprecated(since = "4.0.0")
class ModelData {
    private final ModelSource source;

    }

    /**
     * We use this to map all phases to the lifecycle that contains it. This is used so that a user can specify the
     * phase they want to execute, and we can easily determine what lifecycle we need to run.
     *
     * @return A map of lifecycles, indexed on id
     */
    public Map<String, Lifecycle> getPhaseToLifecycleMap() {