diff --git a/venv/Lib/site-packages/fastapi/.agents/skills/fastapi/references/streaming.md b/venv/Lib/site-packages/fastapi/.agents/skills/fastapi/references/streaming.md new file mode 100644 index 0000000..0832eed --- /dev/null +++ b/venv/Lib/site-packages/fastapi/.agents/skills/fastapi/references/streaming.md @@ -0,0 +1,105 @@ +# Streaming + +## Stream JSON Lines + +To stream JSON Lines, declare the return type and use `yield` to return the data. + +```python +@app.get("/items/stream") +async def stream_items() -> AsyncIterable[Item]: + for item in items: + yield item +``` + +## Server-Sent Events (SSE) + +To stream Server-Sent Events, use `response_class=EventSourceResponse` and `yield` items from the endpoint. + +Plain objects are automatically JSON-serialized as `data:` fields, declare the return type so the serialization is done by Pydantic: + +```python +from collections.abc import AsyncIterable + +from fastapi import FastAPI +from fastapi.sse import EventSourceResponse +from pydantic import BaseModel + +app = FastAPI() + + +class Item(BaseModel): + name: str + price: float + + +@app.get("/items/stream", response_class=EventSourceResponse) +async def stream_items() -> AsyncIterable[Item]: + yield Item(name="Plumbus", price=32.99) + yield Item(name="Portal Gun", price=999.99) +``` + +For full control over SSE fields (`event`, `id`, `retry`, `comment`), yield `ServerSentEvent` instances: + +```python +from collections.abc import AsyncIterable + +from fastapi import FastAPI +from fastapi.sse import EventSourceResponse, ServerSentEvent + +app = FastAPI() + + +@app.get("/events", response_class=EventSourceResponse) +async def stream_events() -> AsyncIterable[ServerSentEvent]: + yield ServerSentEvent(data={"status": "started"}, event="status", id="1") + yield ServerSentEvent(data={"progress": 50}, event="progress", id="2") +``` + +Use `raw_data` instead of `data` to send pre-formatted strings without JSON encoding: + +```python +yield ServerSentEvent(raw_data="plain text line", event="log") +``` + +## Stream bytes + +To stream bytes, declare a `response_class=` of `StreamingResponse` or a sub-class, and use `yield` to return the data. + +```python +from fastapi import FastAPI +from fastapi.responses import StreamingResponse +from app.utils import read_image + +app = FastAPI() + + +class PNGStreamingResponse(StreamingResponse): + media_type = "image/png" + +@app.get("/image", response_class=PNGStreamingResponse) +def stream_image_no_async_no_annotation(): + with read_image() as image_file: + yield from image_file +``` + +prefer this over returning a `StreamingResponse` directly: + +```python +# DO NOT DO THIS + +import anyio +from fastapi import FastAPI +from fastapi.responses import StreamingResponse +from app.utils import read_image + +app = FastAPI() + + +class PNGStreamingResponse(StreamingResponse): + media_type = "image/png" + + +@app.get("/") +async def main(): + return PNGStreamingResponse(read_image()) +```