### Función personalizada para generar ID único { #custom-generate-unique-id-function }

FastAPI usa un **ID único** para cada *path operation*, se usa para el **operation ID** y también para los nombres de cualquier modelo personalizado necesario, para requests o responses.

Puedes personalizar esa función. Toma un `APIRoute` y retorna un string.

**FastAPI** 不強制任何特定的意義。

這裡的資訊作為一個指南，而不是要求。

例如，當使用 GraphQL 時，你通常只使用 `POST` 操作。

///

### 第四步：定義 **路徑操作函式**

這是我們的「**路徑操作函式**」：

* **path**: 是 `/`.
* **operation**: 是 `get`.
* **function**: 是裝飾器下面的函式（在 `@app.get("/")` 下面）。

{* ../../docs_src/first_steps/tutorial001.py h1[7] *}

這就是一個 Python 函式。

它將會在 **FastAPI** 收到一個請求時被呼叫，使用 `GET` 操作。

在這種情況下，它是一個 `async` 函式。

---

const (
	xfs  = "XFS"
	ext4 = "EXT4"
)

// WalkDir will traverse a directory and return all entries found.
// On success a sorted meta cache stream will be returned.
// Metadata has data stripped, if any.
// The function tries to quit as fast as the context is canceled to avoid further drive IO
func (s *xlStorage) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) (err error) {
	legacyFS := s.fsType != xfs && s.fsType != ext4

    "path": "platforms/core-configuration/flow-services",
    "unitTests": false,
    "functionalTests": true,
    "crossVersionTests": false
  },
  {
    "name": "functional",
    "path": "platforms/core-runtime/functional",
    "unitTests": true,
    "functionalTests": false,
    "crossVersionTests": false
  },
  {
    "name": "gradle-cli",
    "path": "platforms/core-runtime/gradle-cli",

	defer nsLock.Unlock(lkctx)

	// Freeze all incoming S3 API calls before running speedtest.
	globalNotificationSys.ServiceFreeze(ctx, true)

	// Unfreeze as soon as request context is canceled or when the function returns.
	go func() {
		<-ctx.Done()
		globalNotificationSys.ServiceFreeze(ctx, false)
	}()

	durationStr := r.Form.Get(peerRESTDuration)
	duration, err := time.ParseDuration(durationStr)

Например, при использовании GraphQL обычно все действия выполняются только с помощью POST-операций.

///

### Шаг 4: определите **функцию операции пути** { #step-4-define-the-path-operation-function }

Вот наша «функция операции пути»:

* **путь**: `/`.
* **операция**: `get`.
* **функция**: функция ниже «декоратора» (ниже `@app.get("/")`).

{* ../../docs_src/first_steps/tutorial001_py39.py hl[7] *}

    build_site_dist_path = build_site_path / lang
    if lang == "en":
        dist_path = site_path
        # Don't remove en dist_path as it might already contain other languages.
        # When running build_all(), that function already removes site_path.
        # All this is only relevant locally, on GitHub Actions all this is done through
        # artifacts and multiple workflows, so it doesn't matter if directories are
        # removed or not.

		cause:      err,
	}
}

func errIllegalSQLFunctionArgument(err error) *s3Error {
	return &s3Error{
		code:       "IllegalSqlFunctionArgument",
		message:    "Illegal argument was used in the SQL function.",
		statusCode: 400,
		cause:      err,
	}
}

func errMultipleDataSourcesUnsupported(err error) *s3Error {
	return &s3Error{
		code:       "MultipleDataSourcesUnsupported",

		jwtgo.ValidationErrorUnverifiable)
}

// ParseWithClaims - parse the token string, valid methods.
func ParseWithClaims(tokenStr string, claims *MapClaims, fn func(*MapClaims) ([]byte, error)) error {
	// Key lookup function has to be provided.
	if fn == nil {
		// keyFunc was not provided, return error.
		return jwtgo.NewValidationError("no Keyfunc was provided.", jwtgo.ValidationErrorUnverifiable)
	}

	bufp := base64BufPool.Get()

Vamos usar as ferramentas fornecidas pelo **FastAPI** para lidar com segurança.

## Como Parece { #how-it-looks }

Vamos primeiro usar o código e ver como funciona, e depois voltaremos para entender o que está acontecendo.

## Crie um `main.py` { #create-main-py }

Copie o exemplo em um arquivo `main.py`:

{* ../../docs_src/security/tutorial001_an_py39.py *}