{* ../../docs_src/dataclasses/tutorial003.py hl[1,5,8:11,14:17,23:25,28] *}

1. Wir importieren `field` weiterhin von Standard-`dataclasses`.

2. `pydantic.dataclasses` ist ein direkter Ersatz für `dataclasses`.

3. Die Datenklasse `Author` enthält eine Liste von `Item`-Datenklassen.

...без додавання обов’язкового параметра `needy`, Ви побачите помилку:

```JSON
{
  "detail": [
    {
      "type": "missing",
      "loc": [
        "query",
        "needy"
      ],
      "msg": "Field required",
      "input": null
    }
  ]
}
```

Оскільки `needy` є обов’язковим параметром, вам потрібно вказати його в URL:

```
http://127.0.0.1:8000/items/foo-item?needy=sooooneedy
```

```JSON
{
    "detail": [
        {
            "loc": [
                "query",
                "needy"
            ],
            "msg": "field required",
            "type": "value_error.missing"
        }
    ]
}
```

Поскольку `needy` является обязательным параметром, вам необходимо указать его в URL-адресе:

```

</a>
<a href="https://pypi.org/project/fastapi" target="_blank">
    <img src="https://img.shields.io/pypi/v/fastapi?color=%2334D058&label=pypi%20package" alt="Package version">
</a>
<a href="https://pypi.org/project/fastapi" target="_blank">
    <img src="https://img.shields.io/pypi/pyversions/fastapi.svg?color=%2334D058" alt="Supported Python versions">
</a>
</p>

---

        assertTrue(exception instanceof Exception);
        assertTrue(exception instanceof Throwable);
    }

    public void test_serialization() {
        // Test that the exception has the correct serialVersionUID field
        ScriptEngineException exception = new ScriptEngineException("Serialization test");

        // Verify the exception can be created and basic properties work
        assertNotNull(exception);

    stream.defaultWriteObject();
    stream.writeObject(keyTypeOrObjectUnderJ2cl);
    Serialization.writeMap(this, stream);
  }

  @SuppressWarnings("unchecked") // reading field populated by writeObject
  @GwtIncompatible // java.io.ObjectInputStream
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();

...sin agregar el parámetro requerido `needy`, verás un error como:

```JSON
{
  "detail": [
    {
      "type": "missing",
      "loc": [
        "query",
        "needy"
      ],
      "msg": "Field required",
      "input": null
    }
  ]
}
```

Como `needy` es un parámetro requerido, necesitarías establecerlo en la URL:

```
http://127.0.0.1:8000/items/foo-item?needy=sooooneedy
```

In this case, **FastAPI** will notice that there is more than one body parameter in the function (there are two parameters that are Pydantic models).

So, it will then use the parameter names as keys (field names) in the body, and expect a body like:

```JSON
{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    },
    "user": {

```JSON
{
    "detail": [
        {
            "loc": [
                "query",
                "needy"
            ],
            "msg": "field required",
            "type": "value_error.missing"
        }
    ]
}
```

Como `needy` é um parâmetro obrigatório, você precisaria defini-lo na URL:

```

      .toUrl()
      .openConnection()
      .getInputStream() // Should succeed.
  }

  /**
   * Throttle the request body by sleeping 500ms after every 3 bytes. With a 6-byte request, this
   * should yield one sleep for a total delay of 500ms.
   */
  @Test
  fun throttleRequest() {
    assumeNotWindows()
    server.enqueue(
      MockResponse()
        .throttleBody(3, 500, TimeUnit.MILLISECONDS),
    )