/// tip | Consejo

Aquí estamos usando `Query()` porque este es un **parámetro de query**. Más adelante veremos otros como `Path()`, `Body()`, `Header()`, y `Cookie()`, que también aceptan los mismos argumentos que `Query()`.

///

FastAPI ahora:

* **Validará** los datos asegurándose de que la longitud máxima sea de 50 caracteres
* Mostrará un **error claro** para el cliente cuando los datos no sean válidos

}

const minReadBufferSize = 16
const maxConsecutiveEmptyReads = 100

// NewReaderSize returns a new [Reader] whose buffer has at least the specified
// size. If the argument io.Reader is already a [Reader] with large enough
// size, it returns the underlying [Reader].
func NewReaderSize(rd io.Reader, size int) *Reader {
	// Is it already a Reader?
	b, ok := rd.(*Reader)

{* ../../docs_src/path_params/tutorial001.py hl[6:7] *}

Der Wert des Pfad-Parameters `item_id` wird Ihrer Funktion als das Argument `item_id` übergeben.

Wenn Sie dieses Beispiel ausführen und auf <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a> gehen, sehen Sie als Response:

```JSON

Se você parar para ver, *funções de operação de rota* são declaradas para serem usadas sempre que uma *rota* e uma *operação* se encaixam, e então o **FastAPI** se encarrega de chamar a função correspondente com os argumentos corretos, extraindo os dados da requisição.

Na verdade, todos (ou a maioria) dos frameworks web funcionam da mesma forma.

///

Lo único nuevo es el `callbacks=invoices_callback_router.routes` como un argumento para el *decorador de path operation*. Veremos qué es eso a continuación.

## Documentar el callback

El código real del callback dependerá mucho de tu propia aplicación API.

	if ns1 != ns2 {
		return fmt.Errorf("Expected number of endpoints %d, seen %d", ns1, ns2)
	}

	for i, cmdLine := range s1.CmdLines {
		if cmdLine != s2.CmdLines[i] {
			return fmt.Errorf("Expected command line argument %s, seen %s", cmdLine,
				s2.CmdLines[i])
		}
	}

	if reflect.DeepEqual(s1.MinioEnv, s2.MinioEnv) {
		return nil
	}

	// Report differences in environment variables.
	var missing []string

     * on an SMB server addressed by the <code>SmbFile</code> parameter. See
     * {@link jcifs.smb.SmbFile} for a detailed description and examples of
     * the smb URL syntax. If the second argument is <code>true</code>, then
     * bytes will be written to the end of the file rather than the beginning.
     *
     * @param file
     *            An <code>SmbFile</code> representing the file to write to

						},
					},
				},
				nil,
				[][]uint64{{
					16, 16, 16, 16, 16, 16, 16, 16,
					16, 16, 16, 16, 16, 16, 16, 16,
				}},
			},
			true,
		},
		// More than 1 ellipses per argument for standalone setup.
		{
			"/export{1...10}/disk{1...10}",
			endpointSet{
				[]ellipses.ArgPattern{
					[]ellipses.Pattern{
						{
							Prefix: "",
							Suffix: "",

      </searchConfiguration>

// [Writer.CreateHeader], [Writer.CreateRaw], or [Writer.Close].
//
// In contrast to [Writer.CreateHeader], the bytes passed to Writer are not compressed.
//
// CreateRaw's argument is stored in w. If the argument is a pointer to the embedded
// [FileHeader] in a [File] obtained from a [Reader] created from in-memory data,
// then w will refer to all of that memory.