Então, com essa declaração de tipo, o **FastAPI** fornece <abbr title="convertendo a string que vem de um request HTTP em dados Python">"parsing"</abbr> automático do request.
///

## Validação de dados { #data-validation }

Mas se você for no navegador para <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a>, verá um bom erro HTTP:

```JSON
{
  "detail": [
    {

/// tip | Consejo

Para entender las variables de entorno, puedes leer [Variables de Entorno](../environment-variables.md){.internal-link target=_blank}.

///

## Tipos y validación { #types-and-validation }

import org.lastaflute.web.Execute;
import org.lastaflute.web.response.HtmlResponse;
import org.lastaflute.web.response.render.RenderData;
import org.lastaflute.web.ruts.process.ActionRuntime;
import org.lastaflute.web.validation.VaMessenger;

import jakarta.annotation.Resource;

/**
 * Admin action for Group management.
 *
 */
public class AdminGroupAction extends FessAdminAction {

    /**
     * Default constructor.

///

### JSON Schema's `examples` field { #json-schemas-examples-field }

But then JSON Schema added an <a href="https://json-schema.org/draft/2019-09/json-schema-validation.html#rfc.section.9.5" class="external-link" target="_blank">`examples`</a> field to a new version of the specification.

Но по умолчанию всё **«просто работает»**.

### Проверка значений { #validation }

* Проверка значений для большинства (или всех?) **типов данных** Python, включая:
    * Объекты JSON (`dict`).
    * Массив JSON (`list`) с определёнными типами элементов.

            logger.warn("Could not get urls: (" + xpath + ", " + attr + ")", e);
        }
        return urlList;
    }

    /**
     * Adds a child URL to the URL list after processing and validation.
     *
     * @param urlList the list to add the URL to
     * @param url the base URL for resolving relative URLs
     * @param attrValue the attribute value containing the URL

Por padrão, tudo **"simplesmente funciona"**.

### Validação { #validation }

* Validação para a maioria dos (ou todos?) **tipos de dados** do Python, incluindo:
    * objetos JSON (`dict`).
    * arrays JSON (`list`), definindo tipos dos itens.

<img src="/img/python-types/image06.png">

## Les modèles Pydantic

<a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> est une bibliothèque Python pour effectuer de la validation de données.

Vous déclarez la forme de la donnée avec des classes et des attributs.

Chaque attribut possède un type.

	// Total length of the alpha numeric table.
	alphaNumericTableLen = byte(len(alphaNumericTable))

	reservedChars = "=,"
)

// Common errors generated for access and secret key validation.
var (
	ErrInvalidAccessKeyLength   = fmt.Errorf("access key length should be between %d and %d", accessKeyMinLen, accessKeyMaxLen)

   *
   * If a challenge uses the `token68` variant instead of auth params, there is exactly one
   * auth param in the challenge at key null. Invalid headers and challenges are ignored.
   * No semantic validation is done, for example that `Basic` auth must have a `realm`
   * auth param, this is up to the caller that interprets these challenges.
   */
  fun challenges(): List<Challenge> {
    return headers.parseChallenges(