# Body - Campos { #body-fields }

De la misma manera que puedes declarar validaciones adicionales y metadatos en los parámetros de las *path operation function* con `Query`, `Path` y `Body`, puedes declarar validaciones y metadatos dentro de los modelos de Pydantic usando `Field` de Pydantic.

## Importar `Field` { #import-field }

Primero, tienes que importarlo:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[4] *}

/// warning | Advertencia

		return 0, err
	}
	var deviceCwd string
	if isStd {
		// Note that we use path.Join here instead of filepath.Join:
		// The device paths should be slash-separated even if the go_android_exec
		// wrapper itself is compiled for Windows.
		deviceCwd = path.Join(deviceGoroot, "src", importPath)
	} else {
		deviceCwd = path.Join(deviceGopath, "src", importPath)
		if modDir != "" {

        wagon.addExpectedContent("path", "lower-case-checksum");
        wagon.addExpectedContent("path.sha1", "2a25dc564a3b34f68237fc849066cbc7bb7a36a1");
        wagonManager.getArtifact(artifact, repo, null, false);

        wagon.clearExpectedContent();
        wagon.addExpectedContent("path", "upper-case-checksum");
        wagon.addExpectedContent("path.sha1", "B7BB97D7D0B9244398D9B47296907F73313663E6");

    try {
      val requestHeaders = stream.takeHeaders()
      var path: String? = null
      var i = 0
      val size = requestHeaders.size
      while (i < size) {
        if (requestHeaders.name(i) == Header.TARGET_PATH_UTF8) {
          path = requestHeaders.value(i)
          break
        }
        i++
      }
      if (path == null) {
        // TODO: send bad request error
        throw AssertionError()

                }
            }
            return builder.build()
        }

        private
        fun processDirectory(dir: Path, builder: Trie.Builder) {
            Files.walkFileTree(dir, object : SimpleFileVisitor<Path>() {
                override fun visitFile(file: Path, attrs: BasicFileAttributes): FileVisitResult {
                    val zipEntry = ZipEntry(dir.relativize(file).toString())

            return url.toString();
        }

        private void concatPath(StringBuilder url, String path) {
            if (!path.isEmpty()) {
                boolean initialUrlEndsWithSlash = url.charAt(url.length() - 1) == '/';
                boolean pathStartsWithSlash = path.charAt(0) == '/';

                if (pathStartsWithSlash) {
                    if (initialUrlEndsWithSlash) {

    route: APIRoute = request.scope["route"]
    return {"user_id": user_id, "path": route.path}


@app.websocket("/items/{item_id}")
async def websocket_item(item_id: str, websocket: WebSocket):
    route: APIWebSocketRoute = websocket.scope["route"]
    await websocket.accept()
    await websocket.send_json({"item_id": item_id, "path": route.path})


client = TestClient(app)


def test_get():

	"github.com/pkg/xattr"
)

var (
	path, name string
	value      uint64
	set, list  bool
)

func getxattr(path, name string) (uint64, error) {
	buf, err := xattr.LGet(path, name)
	if err != nil {
		return 0, err
	}

	return binary.LittleEndian.Uint64(buf[:8]), nil
}

func listxattr(path string) ([]string, error) {
	return xattr.LList(path)
}

func setxattr(path, name string, value uint64) error {

func (k *KeycloakProvider) LookupUser(userid string) (User, error) {
	req, err := http.NewRequest(http.MethodGet, k.adminURL, nil)
	if err != nil {
		return User{}, err
	}
	req.URL.Path = path.Join(req.URL.Path, "realms", k.realm, "users", userid)

	k.Lock()
	accessToken := k.accessToken
	k.Unlock()
	if accessToken.AccessToken == "" {
		return User{}, ErrAccessTokenExpired
	}

Imaginemos que quieres obtener la dirección IP/host del cliente dentro de tu *path operation function*.

Para eso necesitas acceder al request directamente.

{* ../../docs_src/using_request_directly/tutorial001_py39.py hl[1,7:8] *}

Al declarar un parámetro de *path operation function* con el tipo siendo `Request`, **FastAPI** sabrá pasar el `Request` en ese parámetro.

/// tip | Consejo