}


@app.get("/items/{item_id}", response_model=Item)
async def read_item(item_id: str):
    return items[item_id]


@app.patch("/items/{item_id}", response_model=Item)
async def update_item(item_id: str, item: Item):
    stored_item_data = items[item_id]
    stored_item_model = Item(**stored_item_data)
    update_data = item.model_dump(exclude_unset=True)

    size: Union[int, None] = Body(default=None),
):
    if item_id in items:
        item = items[item_id]
        item["name"] = name
        item["size"] = size
        return item
    else:
        item = {"name": name, "size": size}
        items[item_id] = item

from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int = Path(title="The ID of the item to get", ge=0, le=1000),
    q: Union[str, None] = None,
    item: Union[Item, None] = None,
):
    results = {"item_id": item_id}

    @app.post("/items/", responses={402: {"model": Item}})
    def create_item(item: Item) -> Item:
        return item

    @app.post("/items-list/")
    def create_item_list(item: list[Item]):
        return item

    @app.get("/items/")
    def read_items() -> list[Item]:
        return [
            Item(
                name="Portal Gun",

   * dependent on the hash codes they produce will fail sooner.
   */
  @SuppressWarnings("GoodTime") // reading system time without TimeSource
  static final int GOOD_FAST_HASH_SEED = (int) System.currentTimeMillis();

  /**
   * Returns a hash function implementing the <a
   * href="https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp">32-bit murmur3

  static final boolean GENERATE_CANCELLATION_CAUSES;

  static {
    // System.getProperty may throw if the security policy does not permit access.
    boolean generateCancellationCauses;
    try {
      generateCancellationCauses =
          parseBoolean(System.getProperty("guava.concurrent.generate_cancellation_cause", "false"));
    } catch (SecurityException e) {

Supongamos que solo tienes un único parámetro de cuerpo `item` de un modelo Pydantic `Item`.

Por defecto, **FastAPI** esperará su cuerpo directamente.

Pero si deseas que espere un JSON con una clave `item` y dentro de ella los contenidos del modelo, como lo hace cuando declaras parámetros de cuerpo extra, puedes usar el parámetro especial `Body` `embed`:

```Python
item: Item = Body(embed=True)
```

como en:

<div class="announce-wrapper">
  <div id="announce-left">
    <div class="item">
      <a class="announce-link" href="https://fastapicloud.com" target="_blank">
        <span class="twemoji">
          {% include ".icons/material/cloud-arrow-up.svg" %}
        </span> Join the <strong>FastAPI Cloud</strong> waiting list 🚀
      </a>
    </div>
    <div class="item">
      <a class="announce-link" href="https://x.com/fastapi" target="_blank">

}


@app.get("/items/{item_id}", response_model=Item)
async def read_item(item_id: str):
    return items[item_id]


@app.patch("/items/{item_id}", response_model=Item)
async def update_item(item_id: str, item: Item):
    stored_item_data = items[item_id]
    stored_item_model = Item(**stored_item_data)
    update_data = item.model_dump(exclude_unset=True)

        void testReadDataWireFormatWithOffset() {
            byte[] fullBuffer = new byte[200];
            byte[] dfsData = createValidDfsReferralBuffer();
            int offset = 50;
            System.arraycopy(dfsData, 0, fullBuffer, offset, dfsData.length);

            int bytesRead = response.readDataWireFormat(fullBuffer, offset, dfsData.length);

            assertTrue(bytesRead > 0);