有没有办法将html冲到Sinatra的电线上

Question

I have a Sinatra app with a long running process (a web scraper). I'd like the app flush the results of the crawler's progress as the crawler is running instead of at the end.

I've considered forking the request and doing something fancy with ajax but this is a really basic one-pager app that really just needs to output a log to a browser as it's happening. Any suggestions?

Answer 1

更新(2012-03-21)

从Sinatra 1.3.0开始,您可以使用新的流API:

get '/' do
  stream do |out|
    out << "foo\n"
    sleep 10
    out << "bar\n"
  end
end

老答案

不幸的是,你没有可以简单地刷新的流(这不适用于Rack中间件).从路径块返回的结果可以简单地响应each.然后,Rack处理程序将each使用块调用,并在该块中将正文的给定部分刷新到客户端.

所有机架响应必须始终响应each并始终将字符串传递给给定块.如果你只是返回一个字符串,Sinatra会为你处理这个问题.

一个简单的流媒体示例如下:

require 'sinatra'

get '/' do
  result = ["this", " takes", " some", " time"]
  class << result
    def each
      super do |str|
        yield str
        sleep 0.3
      end
    end
  end
  result
end

现在,您只需将所有抓取放入each方法中:

require 'sinatra'

class Crawler
  def initialize(url)
    @url = url
  end

  def each
    yield "opening url\n"
    result = open @url
    yield "seaching for foo\n"
    if result.include? "foo"
      yield "found it\n"
    else
      yield "not there, sorry\n"
    end
  end
end

get '/' do
  Crawler.new 'http://mysite'
end