```JSON
{
  "detail": [
    {
      "type": "int_parsing",
      "loc": [
        "path",
        "item_id"
      ],
      "msg": "Input should be a valid integer, unable to parse string as an integer",
      "input": "foo",
      "url": "https://errors.pydantic.dev/2.1/v/int_parsing"
    }
  ]
}
```

because the path parameter `item_id` had a value of `"foo"`, which is not an `int`.

```JSON
{
  "detail": [
    {
      "type": "int_parsing",
      "loc": [
        "path",
        "item_id"
      ],
      "msg": "Input should be a valid integer, unable to parse string as an integer",
      "input": "foo",
      "url": "https://errors.pydantic.dev/2.1/v/int_parsing"
    }
  ]
}
```

Der Pfad-Parameter `item_id` hatte den Wert `"foo"`, was kein `int` ist.

Then we use the request directly, and extract the body as `bytes`. This means that FastAPI won't even try to parse the request payload as JSON.

And then in our code, we parse that YAML content directly, and then we are again using the same Pydantic model to validate the YAML content:

=== "Pydantic v2"

    ```Python hl_lines="26-33"

```JSON
{
  "detail": [
    {
      "type": "int_parsing",
      "loc": [
        "path",
        "item_id"
      ],
      "msg": "Input should be a valid integer, unable to parse string as an integer",
      "input": "foo",
      "url": "https://errors.pydantic.dev/2.1/v/int_parsing"
    }
  ]
}
```

    ```Python hl_lines="26-33"
    {!> ../../../docs_src/path_operation_advanced_configuration/tutorial007_pv1.py!}
    ```

!!! info
    In Pydantic Version 1 war die Methode zum Parsen und Validieren eines Objekts `Item.parse_obj()`, in Pydantic Version 2 heißt die Methode `Item.model_validate()`.

!!! tip "Tipp"
    Hier verwenden wir dasselbe Pydantic-Modell wieder.

* <a href="https://pythonhosted.org/itsdangerous/" target="_blank"><code>itsdangerous</code></a> - در صورتی که بخواید از `SessionMiddleware` پشتیبانی کنید.

```

En este caso el parámetro de la función `q` será opcional y será `None` por defecto.

!!! check "Revisa"
    También puedes notar que **FastAPI** es lo suficientemente inteligente para darse cuenta de que el parámetro de path `item_id` es un parámetro de path y que `q` no lo es, y por lo tanto es un parámetro de query.

!!! note "Nota"
    FastAPI sabrá que `q` es opcional por el `= None`.