Sync fastapi docs from 11614be9 on 2026-03-11

docs_src/server_sent_events/tutorial004_py310.py

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+from collections.abc import AsyncIterable
+from typing import Annotated
+
+from fastapi import FastAPI, Header
+from fastapi.sse import EventSourceResponse, ServerSentEvent
+from pydantic import BaseModel
+
+app = FastAPI()
+
+
+class Item(BaseModel):
+    name: str
+    price: float
+
+
+items = [
+    Item(name="Plumbus", price=32.99),
+    Item(name="Portal Gun", price=999.99),
+    Item(name="Meeseeks Box", price=49.99),
+]
+
+
+@app.get("/items/stream", response_class=EventSourceResponse)
+async def stream_items(
+    last_event_id: Annotated[int | None, Header()] = None,
+) -> AsyncIterable[ServerSentEvent]:
+    start = last_event_id + 1 if last_event_id is not None else 0
+    for i, item in enumerate(items):
+        if i < start:
+            continue
+        yield ServerSentEvent(data=item, id=str(i))