return new SerializedForm<>(delegate());
  }

    private void readObject(ObjectInputStream stream) throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializedForm");
  }

  /** Serialized form of the map, to avoid serializing the constraint. */
  private static final class SerializedForm<B extends @Nullable Object> implements Serializable {
    private final Map<Class<? extends @NonNull B>, B> backingMap;

Chaque élément produit avec `yield` est encodé en JSON et envoyé dans le champ `data:` d’un événement SSE.

Si vous déclarez le type de retour comme `AsyncIterable[Item]`, FastAPI l’utilisera pour **valider**, **documenter** et **sérialiser** les données avec Pydantic.

{* ../../docs_src/server_sent_events/tutorial001_py310.py ln[1:25] hl[10:12,23] *}

/// tip | Astuce

		} else {
			versions = append(versions, fi)
			allVersionIDs = append(allVersionIDs, fi.VersionID)
		}
	}
	buf, err := xl.AppendTo(nil)
	if err != nil {
		t.Fatalf("Failed to serialize xlmeta %v", err)
	}
	fivs, err := getFileInfoVersions(buf, basefi.Volume, basefi.Name, false)
	if err != nil {
		t.Fatalf("getFileInfoVersions failed: %v", err)
	}
	chkNumVersions := func(fis []FileInfo) bool {

    `com.google.guava:failureaccess:1.0.3`. It also has
    [some annotation-only dependencies][guava-deps], which we discuss in more
    detail at that link.

4.  Serialized forms of ALL objects are subject to change unless noted
    otherwise. Do not persist these and assume they can be read by a future
    version of the library.

			if err != nil {
				err = msgp.WrapError(err)
				return
			}
		}
	}
	o = bts
	return
}

// Msgsize returns an upper bound estimate of the number of bytes occupied by the serialized message
func (z *ServerSystemConfig) Msgsize() (s int) {
	s = 1 + 11 + msgp.IntSize + 9 + msgp.ArrayHeaderSize
	for za0001 := range z.CmdLines {
		s += msgp.StringPrefixSize + len(z.CmdLines[za0001])
	}

```

</div>

Ensuite, allez sur l'UI `/docs`, vous verrez que **FastAPI** utilise ces **modèles** pour **documenter** l'API, et les utilisera aussi pour **sérialiser** et **valider** les données.

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Mettre à jour l'application avec plusieurs modèles { #update-the-app-with-multiple-models }

        AtomicDouble a = new AtomicDouble(x);
        double z = a.addAndGet(y);
        assertBitEquals(x + y, z);
        assertBitEquals(x + y, a.get());
      }
    }
  }

  /** a deserialized serialized atomic holds same value */
  public void testSerialization() throws Exception {
    AtomicDouble a = new AtomicDouble();
    AtomicDouble b = serialClone(a);
    assertThat(b).isNotSameInstanceAs(a);
    a.set(-22.0);

    return new SerializedForm<>(delegate());
  }

    private void readObject(ObjectInputStream stream) throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializedForm");
  }

  /** Serialized form of the map, to avoid serializing the constraint. */
  private static final class SerializedForm<B extends @Nullable Object> implements Serializable {
    private final Map<Class<? extends @NonNull B>, B> backingMap;

      hashCode = ~~hashCode;
      // needed to deal with GWT integer overflow
    }
    return hashCode;
  }

  /*
   * Serializes ImmutableLists as their logical contents. This ensures that
   * implementation types do not leak into the serialized representation.
   */
  @J2ktIncompatible // serialization
  static final class SerializedForm implements Serializable {
    final Object[] elements;

  }

  /** Returns the value of this {@code AtomicDouble} as a {@code double}. */
  @Override
  public double doubleValue() {
    return get();
  }

  /**
   * Saves the state to a stream (that is, serializes it).
   *
   * @serialData The current value is emitted (a {@code double}).
   */
  private void writeObject(ObjectOutputStream s) throws IOException {
    s.defaultWriteObject();

    s.writeDouble(get());