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Yield Styles

@sse_stream accepts any of these yield styles — use whichever feels most natural.

Plain string

The simplest style — yields an unnamed message event.

@sse_stream
def view(request):
    yield "hello"
    yield "world"

Wire format: 

data: hello

data: world

Tuple — (event, data)

The most common style. data can be any JSON-serialisable value.

@sse_stream
def view(request):
    yield ("update", {"count": 1})
    yield ("update", {"count": 2})
    yield ("complete", "done")

Wire format: 

event: update
data: {"count": 1}

event: update
data: {"count": 2}

event: complete
data: done

Tuple — (event, data, id)

Same as above, but includes an event ID. Useful for client-side reconnection — the browser sends the last id in the Last-Event-ID header on reconnect.

@sse_stream
def view(request):
    yield ("update", {"count": 1}, "evt-001")
    yield ("update", {"count": 2}, "evt-002")

Wire format: 

event: update
data: {"count": 1}
id: evt-001

event: update
data: {"count": 2}
id: evt-002

Dict with "data" key

Maps directly to SSEEvent fields. Useful when you want to pass all fields in one expression.

@sse_stream
def view(request):
    yield {"data": "hello", "event": "greet"}
    yield {"data": {"count": 1}, "event": "update", "id": "evt-1"}

Supported keys: data, event, id, retry.

Dict without "data" key

The entire dict is serialised as JSON and used as the event payload.

@sse_stream
def view(request):
    yield {"foo": "bar", "count": 42}

Wire format: 

data: {"foo": "bar", "count": 42}

SSEEvent object

Full control over every SSE field.

from django_flosse import SSEEvent

@sse_stream
def view(request):
    yield SSEEvent(
        data  = {"status": "done"},
        event = "complete",
        id    = "final",
        retry = 5000,       # tell browser: wait 5s before reconnecting
    )

Wire format: 

retry: 5000
id: final
event: complete
data: {"status": "done"}

Summary

What you yield Event name Has ID Has retry
"hello" (unnamed) ✗ ✗
("update", data) update ✗ ✗
("update", data, "id-1") update ✓ ✗
{"data": x, "event": "e"} e ✓* ✓*
{"foo": "bar"} (unnamed) ✗ ✗
SSEEvent(data=x, event="e", id="1") e ✓ ✓

Tip

Dict data and all non-string values are serialised to JSON automatically. You never need to call json.dumps() yourself.