## Importe `Field`

Primeiro, você tem que importá-lo:

```Python hl_lines="4"
{!../../docs_src/body_fields/tutorial001.py!}
```

/// warning | "Aviso"

Note que `Field` é importado diretamente do `pydantic`, não do `fastapi` como todo o resto (`Query`, `Path`, `Body`, etc).

///

func (z *BatchJobKV) DecodeMsg(dc *msgp.Reader) (err error) {
	var field []byte
	_ = field
	var zb0001 uint32
	zb0001, err = dc.ReadMapHeader()
	if err != nil {
		err = msgp.WrapError(err)
		return
	}
	for zb0001 > 0 {
		zb0001--
		field, err = dc.ReadMapKeyPtr()
		if err != nil {
			err = msgp.WrapError(err)
			return
		}
		switch msgp.UnsafeString(field) {
		case "Key":
			z.Key, err = dc.ReadString()

	public static final field INSTANCE Lmockwebserver3/SocketPolicy$DisconnectAtStart;
}

public final class mockwebserver3/SocketPolicy$DisconnectDuringRequestBody : mockwebserver3/SocketPolicy {
	public static final field INSTANCE Lmockwebserver3/SocketPolicy$DisconnectDuringRequestBody;
}

public final class mockwebserver3/SocketPolicy$DisconnectDuringResponseBody : mockwebserver3/SocketPolicy {

          <required>true</required>
          <type>String</type>
        </field>
        <field>
          <name>version</name>
          <description>The version of the extension.</description>
          <version>1.0.0+</version>
          <required>true</required>
          <type>String</type>
        </field>
        <field>
          <name>classLoadingStrategy</name>

                    "type": "missing",
                    "loc": ["body", "item"],
                    "msg": "Field required",
                    "input": None,
                },
                {
                    "type": "missing",
                    "loc": ["body", "user"],
                    "msg": "Field required",
                    "input": None,
                },
                {

                    "type": "missing",
                    "loc": ["body", "item"],
                    "msg": "Field required",
                    "input": None,
                },
                {
                    "type": "missing",
                    "loc": ["body", "user"],
                    "msg": "Field required",
                    "input": None,
                },
                {

                    "type": "missing",
                    "loc": ["body", "item"],
                    "msg": "Field required",
                    "input": None,
                },
                {
                    "type": "missing",
                    "loc": ["body", "user"],
                    "msg": "Field required",
                    "input": None,
                },
                {

                )
    new_field = create_model_field(name=field.name, type_=use_type)
    new_field.has_alias = field.has_alias  # type: ignore[attr-defined]
    new_field.alias = field.alias  # type: ignore[misc]
    new_field.class_validators = field.class_validators  # type: ignore[attr-defined]
    new_field.default = field.default  # type: ignore[misc]
    new_field.required = field.required  # type: ignore[misc]

            {
                "type": "missing",
                "loc": ["body", "username"],
                "msg": "Field required",
                "input": {},
            },
            {
                "type": "missing",
                "loc": ["body", "password"],
                "msg": "Field required",
                "input": {},
            },
        ]
    }


@needs_pydanticv2
@needs_py39

                    field.alias
                    if field.alias != field.name
                    else field.name.replace("_", "-")
                )
        value = _get_multidict_value(field, received_params, alias=alias)
        if value is not None:
            params_to_process[field.name] = value
        processed_keys.add(alias or field.alias)
        processed_keys.add(field.name)