fields_to_extract = get_cached_model_fields(first_field.type_)
        single_not_embedded_field = True
        # If headers are in a Pydantic model, the way to disable convert_underscores
        # would be with Header(convert_underscores=False) at the Pydantic model level
        default_convert_underscores = getattr(
            first_field.field_info, "convert_underscores", True
        )

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

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.model.building;

import java.io.File;
import java.net.URI;
import java.nio.file.Files;
import java.nio.file.Path;

import org.apache.maven.building.FileSource;

/**
 * Wraps an ordinary {@link File} as a model source.
 *
 * @deprecated use {@code org.apache.maven.api.services.ModelBuilder} instead
 */

        app = FastAPI()

        @app.get("/", responses={"500": {"model": NonPydanticModel}})
        def read_root():
            pass  # pragma: nocover


def test_invalid_response_model_sub_type_in_responses_raises():
    with pytest.raises(FastAPIError):
        app = FastAPI()

        @app.get("/", responses={"500": {"model": list[NonPydanticModel]}})
        def read_root():

 * under the License.
 */
package org.apache.maven.profiles.activation;

import java.io.File;
import java.io.IOException;

import org.apache.maven.model.Activation;
import org.apache.maven.model.ActivationFile;
import org.apache.maven.model.Profile;
import org.codehaus.plexus.interpolation.EnvarBasedValueSource;
import org.codehaus.plexus.interpolation.InterpolationException;

    }

    /**
     * Gets the interim result of the model building up to the point where it failed.
     *
     * @return The interim model building result or {@code null} if not available.
     */
    public ModelBuilderResult getResult() {
        return result;
    }

    /**
     * Gets the identifier of the POM whose effective model could not be built. The general format of the identifier is

 * limitations under the License.
 */

package gradlebuild.docs.dsl.docbook;

import gradlebuild.docs.dsl.docbook.model.BlockDoc;
import gradlebuild.docs.dsl.docbook.model.ClassDoc;
import gradlebuild.docs.dsl.docbook.model.ClassExtensionDoc;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

import java.util.Collection;

class BlocksRenderer implements ClassDocMemberRenderer {

 */
package gradlebuild.docs.dsl.docbook;

import gradlebuild.docs.dsl.source.TypeNameResolver;
import gradlebuild.docs.dsl.source.model.ClassMetaData;
import gradlebuild.docs.dsl.source.model.MethodMetaData;
import gradlebuild.docs.dsl.source.model.TypeMetaData;
import gradlebuild.docs.model.ClassMetaDataRepository;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

import java.util.ArrayList;

# Retornando uma Resposta Diretamente { #return-a-response-directly }

Quando você cria uma *operação de rota* no **FastAPI** você pode retornar qualquer dado nela: um dicionário (`dict`), uma lista (`list`), um modelo do Pydantic ou do seu banco de dados, etc.

Por padrão, o **FastAPI** irá converter automaticamente o valor do retorno para JSON utilizando o `jsonable_encoder` explicado em [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank}.

import gradlebuild.docs.XmlSpecification
import gradlebuild.docs.dsl.docbook.model.ClassDoc
import gradlebuild.docs.dsl.docbook.model.ExtraAttributeDoc
import gradlebuild.docs.dsl.docbook.model.PropertyDoc
import gradlebuild.docs.dsl.source.model.ClassMetaData
import gradlebuild.docs.dsl.source.model.PropertyMetaData
import gradlebuild.docs.dsl.source.model.TypeMetaData

class ClassDocPropertiesBuilderTest extends XmlSpecification {