participant handler as Exception handler
participant dep as Dep with yield
participant operation as Path Operation
participant tasks as Background tasks

    Note over client,tasks: Can raise exception for dependency, handled after response is sent
    Note over client,operation: Can raise HTTPException and can change the response
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise

  ImmediateExecutionOperation* CreateOperation() override = 0;

  // Returns whether the runtime is backed by TFRT or the legacy TF Eager
  // Runtime. This is necessary to decouple runtime-dependent
  // code that is layered on top of the runtime.
  virtual bool UsesTFRT() = 0;

  // List attributes of available devices
  virtual void ListDevices(std::vector<DeviceAttributes>* devices) = 0;

	case TypeFifo:
		mode |= fs.ModeNamedPipe
	}

	return mode
}

func (fi headerFileInfo) String() string {
	return fs.FormatFileInfo(fi)
}

// sysStat, if non-nil, populates h from system-dependent fields of fi.
var sysStat func(fi fs.FileInfo, h *Header, doNameLookups bool) error

const (
	// Mode constants from the USTAR spec:

participant handler as Exception handler
participant dep as Dep with yield
participant operation as Path Operation
participant tasks as Background tasks

    Note over client,tasks: Can raise exception for dependency, handled after response is sent
    Note over client,operation: Can raise HTTPException and can change the response
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise

	"Misdirected Request":             http.StatusMisdirectedRequest,
	"Unprocessable Entity":            http.StatusUnprocessableEntity,
	"Locked":                          http.StatusLocked,
	"Failed Dependency":               http.StatusFailedDependency,
	"Too Early":                       http.StatusTooEarly,
	"Upgrade Required":                http.StatusUpgradeRequired,

There you can set:

* The "Item ID", used in the path.
* The "Token" used as a query parameter.

/// tip

Notice that the query `token` will be handled by a dependency.

///

With that you can connect the WebSocket and then send and receive messages:

<img src="/img/tutorial/websockets/image05.png">

## Handling disconnections and multiple clients

Isso é que nós iremos resolver, vamos carregar o modelo antes das requisições serem manuseadas, mas apenas um pouco antes da aplicação começar a receber requisições, não enquanto o código estiver sendo carregado.

O "fluxo" da `senha` é um dos caminhos ("fluxos") definidos no OAuth2, para lidar com a segurança e autenticação.

OAuth2 foi projetado para que o backend ou a API pudesse ser independente do servidor que autentica o usuário.

Mas nesse caso, a mesma aplicação **FastAPI** irá lidar com a API e a autenticação.

Então, vamos rever de um ponto de vista simplificado:

# Klassen als Abhängigkeiten

Bevor wir tiefer in das **Dependency Injection** System eintauchen, lassen Sie uns das vorherige Beispiel verbessern.

## Ein `dict` aus dem vorherigen Beispiel

Im vorherigen Beispiel haben wir ein `dict` von unserer Abhängigkeit („Dependable“) zurückgegeben:

//// tab | Python 3.10+

```Python hl_lines="9"
{!> ../../docs_src/dependencies/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

    * The cache can be disabled per dependency declaration, using `use_cache=False` as in `Depends(your_dependency, use_cache=False)`.
    * Updated docs at: [Using the same dependency multiple times](https://fastapi.tiangolo.com/tutorial/dependencies/sub-dependencies/#using-the-same-dependency-multiple-times).
    * PR [#292](https://github.com/tiangolo/fastapi/pull/292).