Nesse caso, você pode simplesmente trocar as `dataclasses` padrão por `pydantic.dataclasses`, que é um substituto direto:

{* ../../docs_src/dataclasses_/tutorial003_py310.py hl[1,4,7:10,13:16,22:24,27] *}

1. Ainda importamos `field` das `dataclasses` padrão.

2. `pydantic.dataclasses` é um substituto direto para `dataclasses`.

3. A dataclass `Author` inclui uma lista de dataclasses `Item`.

{* ../../docs_src/dataclasses_/tutorial003_py310.py hl[1,4,7:10,13:16,22:24,27] *}

1. Todavía importamos `field` de los `dataclasses` estándar.

2. `pydantic.dataclasses` es un reemplazo directo para `dataclasses`.

3. El dataclass `Author` incluye una lista de dataclasses `Item`.

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

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

...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
```

			return err
		}
	case !f.Tag.IsEmpty():
		if err := e.EncodeElement(f.Tag, xml.StartElement{Name: xml.Name{Local: "Tag"}}); err != nil {
			return err
		}
	default:
		// Always print Prefix field when both And & Tag are empty
		if err := e.EncodeElement(f.Prefix, xml.StartElement{Name: xml.Name{Local: "Prefix"}}); err != nil {
			return err
		}

		if f.ObjectSizeLessThan > 0 {

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

La présence de `needy` étant nécessaire, vous auriez besoin de l'insérer dans l'URL :

```

			case *ast.StructType:
				return true // recurse into fields
			case *ast.InterfaceType:
				return true // recurse into methods
			case *ast.FieldList:
				return true // recurse into fields
			case *ast.ValueSpec:
				if isDeprecated(n.Doc) {
					for _, id := range n.Names {
						mark(id)
					}
				}
				return false
			case *ast.Field:
				if isDeprecated(n.Doc) {

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

Da `needy` ein erforderlicher Parameter ist, müssen Sie ihn in der URL setzen:

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

本例把标准的 `dataclasses` 直接替换为 `pydantic.dataclasses`：

```{ .python .annotate hl_lines="1  5  8-11  14-17  23-25  28" }
{!../../docs_src/dataclasses_/tutorial003.py!}
```

1. 本例依然要从标准的 `dataclasses` 中导入 `field`；

2. 使用 `pydantic.dataclasses` 直接替换 `dataclasses`；

3. `Author` 数据类包含 `Item` 数据类列表；

4. `Author` 数据类用于 `response_model` 参数；

5. 其它带有数据类的标准类型注解也可以作为请求体；

    本例使用的是 `Item` 数据类列表；