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

    Note over client,operation: Can raise exceptions, including HTTPException
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise Exception
        dep -->> handler: Raise Exception

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

    Note over client,operation: Can raise exceptions, including HTTPException
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise Exception
        dep -->> handler: Raise Exception

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

    Note over client,operation: Can raise exceptions, including HTTPException
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise Exception
        dep -->> handler: Raise Exception

        ] = None,
        on_startup: Annotated[
            Sequence[Callable[[], Any]] | None,
            Doc(
                """
                A list of startup event handler functions.

                You should instead use the `lifespan` handlers.

                Read more in the [FastAPI docs for `lifespan`](https://fastapi.tiangolo.com/advanced/events/).
                """
            ),
        ] = None,

FastAPI 0.106.0 より前では、`yield` の後で例外を送出することはできませんでした。`yield` を持つ依存関係の終了コードはレスポンス送信「後」に実行されるため、[例外ハンドラ](../tutorial/handling-errors.md#install-custom-exception-handlers)はすでに実行済みでした。

これは主に、依存関係が "yield" した同じオブジェクトをバックグラウンドタスク内で利用できるようにするための設計でした。終了コードはバックグラウンドタスク完了後に実行されるからです。

これは、レスポンスがネットワーク上を移動するのを待っている間にリソースを保持しないようにする意図で、FastAPI 0.106.0 で変更されました。

/// tip | 豆知識

        } catch (AuthorizationException e) {
            throw new TransferFailedException("Authorization failed: " + e.getMessage(), e);
        } finally {
            // Remove remaining TransferListener instances (checksum handlers removed in above finally clause)
            if (downloadMonitor != null) {
                wagon.removeTransferListener(downloadMonitor);
            }

            disconnectWagon(wagon);

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

    Note over client,operation: Can raise exceptions, including HTTPException
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise Exception
        dep -->> handler: Raise Exception

	globalRemoteTargetTransport = NewRemoteTargetHTTPTransport(false)()
	globalProxyEndpoints = GetProxyEndpoints(globalEndpoints, globalRemoteTargetTransport)

	globalForwarder = handlers.NewForwarder(&handlers.Forwarder{
		PassHost:     true,
		RoundTripper: globalRemoteTargetTransport,
		Logger: func(err error) {
			if err != nil && !errors.Is(err, context.Canceled) {
				proxyLogIf(GlobalContext, err)
			}

	for i := riscv.REG_X0; i <= riscv.REG_X31; i++ {
		// Disallow X3 in shared mode, as this will likely be used as the
		// GP register, which could result in problems in non-Go code,
		// including signal handlers.
		if shared && i == riscv.REG_GP {
			continue
		}
		if i == riscv.REG_TP || i == riscv.REG_G {
			continue
		}
		name := fmt.Sprintf("X%d", i-riscv.REG_X0)
		register[name] = int16(i)
	}

	handler2 := func(req *testRequest) (resp *testResponse, err *RemoteErr) {
		r := RemoteErr(req.String)
		return nil, &r
	}
	errFatal(h1.Register(local, handler1))
	errFatal(h2.Register(local, handler2))

	errFatal(h1.Register(remote, handler1))
	errFatal(h2.Register(remote, handler2))

	// local to remote connection