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


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


@app.get("/story/stream-bytes", response_class=StreamingResponse)

```

## 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 iter_data():
        yield json.dumps({"is_open": session.open})

    return StreamingResponse(iter_data())


@app.get("/request-scope")
def request_scope(session: SessionRequestDep) -> Any:
    def iter_data():
        yield json.dumps({"is_open": session.open})

    return StreamingResponse(iter_data())


@app.get("/two-scopes")
def get_stream_session(

def get_stream_simple(session: SessionDep) -> Any:
    def iter_data():
        yield from ["x", "y", "z"]

    return StreamingResponse(iter_data())


@app.get("/stream-session")
def get_stream_session(session: SessionDep) -> Any:
    def iter_data():
        yield from session

    return StreamingResponse(iter_data())


@app.get("/broken-session-data")
def get_broken_session_data(session: BrokenSessionDep) -> Any:

## A `StreamingResponse` with `yield` { #a-streamingresponse-with-yield }

If you declare a `response_class=StreamingResponse` in your *path operation function*, you can use `yield` to send each chunk of data in turn.

{* ../../docs_src/stream_data/tutorial001_py310.py ln[1:23] hl[20,23] *}

你也可以用它來串流大型二進位檔案，邊讀邊將每個區塊（chunk）串流出去，而不必一次把整個檔案載入記憶體。

你也可以用同樣方式串流視訊或音訊，甚至可以在處理的同時即時產生並傳送。

## 使用 `yield` 的 `StreamingResponse` { #a-streamingresponse-with-yield }

如果在你的路徑操作函式中宣告 `response_class=StreamingResponse`，就可以用 `yield` 逐一送出每個資料區塊。

{* ../../docs_src/stream_data/tutorial001_py310.py ln[1:23] hl[20,23] *}

FastAPI 會如實將每個資料區塊交給 `StreamingResponse`，不會嘗試將其轉換為 JSON 或其他格式。

### 非 async 路徑操作函式 { #non-async-path-operation-functions }

import anyio
from fastapi import FastAPI
from fastapi.responses import StreamingResponse

app = FastAPI()


async def fake_video_streamer():
    for i in range(10):
        yield b"some fake video bytes"
        await anyio.sleep(0)


@app.get("/")
async def main():

from fastapi import FastAPI
from fastapi.responses import StreamingResponse

some_file_path = "large-video-file.mp4"
app = FastAPI()


@app.get("/")
def main():
    def iterfile():  # (1)
        with open(some_file_path, mode="rb") as file_like:  # (2)
            yield from file_like  # (3)

import base64
from collections.abc import AsyncIterable, Iterable
from io import BytesIO

from fastapi import FastAPI
from fastapi.responses import StreamingResponse

你也可以用它来流式传输大型二进制文件，在读取的同时按块发送，无需一次性把所有内容读入内存。

你还可以用这种方式流式传输视频或音频，甚至可以在处理的同时生成并发送。

## 使用 `yield` 的 `StreamingResponse` { #a-streamingresponse-with-yield }

如果你在*路径操作函数*中声明 `response_class=StreamingResponse`，你就可以使用 `yield` 依次发送每个数据块。

{* ../../docs_src/stream_data/tutorial001_py310.py ln[1:23] hl[20,23] *}

FastAPI 会将每个数据块原样交给 `StreamingResponse`，不会尝试将其转换为 JSON 或做类似处理。

### 非 async 的*路径操作函数* { #non-async-path-operation-functions }