///

## Stream SSE with FastAPI { #stream-sse-with-fastapi }

To stream SSE with FastAPI, use `yield` in your *path operation function* and set `response_class=EventSourceResponse`.

Import `EventSourceResponse` from `fastapi.sse`:

{* ../../docs_src/server_sent_events/tutorial001_py310.py ln[1:25] hl[4,22] *}

Each yielded item is encoded as JSON and sent in the `data:` field of an SSE event.

And when using `Depends(scope="request")` (the default), the exit code after `yield` is executed after the response is sent.

You can read more about it in the docs for [Dependencies with `yield` - Early exit and `scope`](../tutorial/dependencies/dependencies-with-yield.md#early-exit-and-scope).

### Dependencies with `yield` and `StreamingResponse`, Technical Details { #dependencies-with-yield-and-streamingresponse-technical-details }

			Fields: []schema.IndexOption{
				{Field: &schema.Field{Name: "FieldD"}},
				// Note: Duplicate Columns
				{Field: &schema.Field{Name: "FieldD"}},
			},
		},
		{
			Name:  "uniq_field_e1_e2",
			Class: "UNIQUE",
			Fields: []schema.IndexOption{
				{Field: &schema.Field{Name: "FieldE1"}},
				{Field: &schema.Field{Name: "FieldE2"}},
			},
		},
		{
			Name:  "uniq_field_f1_f2",

## SSE mit FastAPI streamen { #stream-sse-with-fastapi }

Um SSE mit FastAPI zu streamen, verwenden Sie `yield` in Ihrer *Pfadoperation-Funktion* und setzen Sie `response_class=EventSourceResponse`.

Importieren Sie `EventSourceResponse` aus `fastapi.sse`:

{* ../../docs_src/server_sent_events/tutorial001_py310.py ln[1:25] hl[4,22] *}

Jedes mit `yield` zurückgegebene Element wird als JSON kodiert und im Feld `data:` eines SSE-Events gesendet.

使用 `Depends(scope="function")` 時，`yield` 之後的結束程式碼會在「路徑操作函式」執行完畢後立刻執行，在回應發送回客戶端之前。

而當使用 `Depends(scope="request")`（預設值）時，`yield` 之後的結束程式碼會在回應送出之後才執行。

你可以在文件中閱讀更多：[含有 `yield` 的相依 - 提前結束與 `scope`](../tutorial/dependencies/dependencies-with-yield.md#early-exit-and-scope)。

### 含有 `yield` 與 `StreamingResponse` 的相依，技術細節 { #dependencies-with-yield-and-streamingresponse-technical-details }

在 FastAPI 0.118.0 之前，如果你使用含有 `yield` 的相依，它會在「路徑操作函式」回傳之後、發送回應之前，執行結束程式碼。

Puedes leer más al respecto en la documentación de [Dependencias con `yield` - Salida temprana y `scope`](../tutorial/dependencies/dependencies-with-yield.md#early-exit-and-scope).

### Dependencias con `yield` y `StreamingResponse`, detalles técnicos { #dependencies-with-yield-and-streamingresponse-technical-details }

    for line in message.splitlines():
        yield line


@app.get("/story/stream-no-async", response_class=StreamingResponse)
def stream_story_no_async() -> Iterable[str]:
    for line in message.splitlines():
        yield line


@app.get("/story/stream-no-annotation", response_class=StreamingResponse)
async def stream_story_no_annotation():
    for line in message.splitlines():
        yield line

///

### `yield from` { #yield-from }

Cuando estés iterando sobre algo, como un objeto tipo archivo, y estés haciendo `yield` para cada elemento, también podrías usar `yield from` para hacer `yield` de cada elemento directamente y saltarte el `for`.

///

### `yield from` { #yield-from }

Когда вы итерируетесь по чему‑то, например, по «файлоподобному» объекту, и делаете `yield` для каждого элемента, вы можете также использовать `yield from`, чтобы отдавать каждый элемент напрямую и не писать цикл `for`.

Это не специфично для FastAPI, это просто Python, но полезный приём. 😎

            if self.open:
                yield item
            else:
                raise ValueError("Session closed")


@contextmanager
def acquire_session() -> Generator[Session, None, None]:
    session = Session()
    try:
        yield session
    finally:
        session.open = False


def dep_session() -> Any:
    with acquire_session() as s:
        yield s


def broken_dep_session() -> Any: