请求流
Sanic允许您按流获取请求数据,如下所示。请求结束时,等待request.stream.read()返回None。只有post,put和patch装饰器具有stream参数。
from sanic import Sanic from sanic.views import CompositionView from sanic.views import HTTPMethodView from sanic.views import stream as stream_decorator from sanic.blueprints import Blueprint from sanic.response import stream, text bp = Blueprint('blueprint_request_stream') app = Sanic('request_stream') class SimpleView(HTTPMethodView): @stream_decorator async def post(self, request): result = '' while True: body = await request.stream.read() if body is None: break result += body.decode('utf-8') return text(result) @app.post('/stream', stream=True) async def handler(request): async def streaming(response): while True: body = await request.stream.read() if body is None: break body = body.decode('utf-8').replace('1', 'A') await response.write(body) return stream(streaming) @bp.put('/bp_stream', stream=True) async def bp_put_handler(request): result = '' while True: body = await request.stream.read() if body is None: break result += body.decode('utf-8').replace('1', 'A') return text(result) # You can also use `bp.add_route()` with stream argument async def bp_post_handler(request): result = '' while True: body = await request.stream.read() if body is None: break result += body.decode('utf-8').replace('1', 'A') return text(result) bp.add_route(bp_post_handler, '/bp_stream', methods=['POST'], stream=True) async def post_handler(request): result = '' while True: body = await request.stream.read() if body is None: break result += body.decode('utf-8') return text(result) app.blueprint(bp) app.add_route(SimpleView.as_view(), '/method_view') view = CompositionView() view.add(['POST'], post_handler, stream=True) app.add_route(view, '/composition_view') if __name__ == '__main__': app.run(host='127.0.0.1', port=8000)
响应流
Sanic允许您使用stream方法将内容流式传输到客户端。此方法接受协程回调,该回调传递给写入的StreamingHTTPResponse对象。一个简单的例子如下:
from sanic import Sanic from sanic.response import stream app = Sanic(__name__) @app.route("/") async def test(request): async def sample_streaming_fn(response): await response.write('foo,') await response.write('bar') return stream(sample_streaming_fn, content_type='text/csv')
在要将内容流传输到源自外部服务(例如数据库)的客户端的情况下,这很有用。例如,您可以使用asyncpg提供的异步游标将数据库记录流式传输到客户端:
@app.route("/") async def index(request): async def stream_from_db(response): conn = await asyncpg.connect(database='test') async with conn.transaction(): async for record in conn.cursor('SELECT generate_series(0, 10)'): await response.write(record[0]) return stream(stream_from_db)
如果客户端支持HTTP / 1.1,Sanic将使用分块传输编码;您可以使用流功能的分块选项显式启用或禁用它。
文件流
Sanic提供sanic.response.file_stream函数,该函数在您要发送大文件时很有用。它返回一个StreamingHTTPResponse对象,默认情况下将使用分块传输编码。因此,Sanic不在响应中添加Content-Length HTTP标头。如果要使用此标头,则可以禁用分块传输编码并手动添加它:
from aiofiles import os as async_os from sanic.response import file_stream @app.route("/") async def index(request): file_path = "/srv/www/whatever.png" file_stat = await async_os.stat(file_path) headers = {"Content-Length": str(file_stat.st_size)} return await file_stream( file_path, headers=headers, chunked=False, )