龙卷风 异步HTTPClient 动态添加 http_client.fetch 到列表

Question

>这里是代码

class GetdataHandler(tornado.web.RequestHandler):
    @tornado.web.asynchronous
    @tornado.gen.engine
    def get(self):
        http_client = tornado.httpclient.AsyncHTTPClient()
        response1, response2, response3, response4, response5, response6, response7, response8, response9, response10 = yield [
        http_client.fetch('http://u.com/order/fa-huo?id=85223'),
        http_client.fetch('http://u.com/order/fa-huo?id=85224'),
        http_client.fetch('http://u.com/order/fa-huo?id=85225'),
        http_client.fetch('http://u.com/order/fa-huo?id=85226'),
        http_client.fetch('http://u.com/order/fa-huo?id=85227'),
        http_client.fetch('http://u.com/order/fa-huo?id=85228'),
        http_client.fetch('http://u.com/order/fa-huo?id=85229'),
        http_client.fetch('http://u.com/order/fa-huo?id=85230'),
        http_client.fetch('http://u.com/order/fa-huo?id=85231'),
        http_client.fetch('http://u.com/order/fa-huo?id=85232')]
        self.write('getData: %s  getData: %s  getData: %s  getData: %s  getData: %s  getData: %s  getData: %s  getData: %s  getData: %s  getData: %s'%(response1.body,response2.body,response3.body,response4.body,response5.body,response6.body,response7.body,response8.body,response9.body,response10.body))
        self.finish()

这是一种愚蠢的方式。我会从 mysql 获取 ID。我不知道我需要申请多少个 ID。我不知道如何使用（for）来做到这一点。任何建议将不胜感激。

Answer 1

使用简单的 'for，将需要额外的列表

ids = [111,222,333,444]
futures = []
for iid in ids:
    futures.append(http_client.fetch(url + iid)
responses = yield futures
# prepare output to user
bodies = []
for r in responses:
    bodies.append(r.body)
# join list of response bodies 
output = ' '.join(bodies) 
self.write(output)

或者您可以使用列表理解

class GetdataHandler(tornado.web.RequestHandler):
    @tornado.web.asynchronous
    @tornado.gen.engine
    def get(self):
        http_client = tornado.httpclient.AsyncHTTPClient()
        url = 'http://u.com/order/fa-huo?id={}'
        ids = [111,222,333,444]  
        # from GET/POST params 
        # ids = self.get_arguments('ids')
        responses = yield [
            http_client.fetch(url.format(iid)) for iid in ids
        ]
        output = ' '.join(
            ['getData: {}'.format(r.body) for r in responses]
        )
        self.write(output)   
        self.finish()

但请注意，缺少错误处理。例如 - 如果其中一个fetch引发异常，您将不会得到任何结果，您应该使用错误处理包装一些函数（可能在 fetch 中使用raise_exception参数）。

更多信息：

• Python 列表理解解释

• https://emptysqua.re/blog/multiple-asynchronous-events-tornado/