Rails 流控制器中的意外过滤器行为

Question

当Ruby on Rails 3: Streaming data through Rails to client 中所示的流式传输时，我遇到了 after_filter 和 around_filter 在响应之前完成执行的问题。我需要在执行 after_filters 之前流式传输响应，因为我们依赖于在这些过滤器中清理的数据。我正在使用乘客。

示例控制器：

class Asdf
  def each
    (1..5).each do |num|
      sleep(1)
      Rails.logger.info "STREAMING LINE #{num}"
      yield "test#{num}\n"
    end
  end
end

class WelcomeController < ApplicationController
  before_filter :before
  after_filter :after

  around_filter do |controller, action|
    logger.debug "around_filter prior to action"
    action.call
    logger.debug "around_filter after action"
  end

  def index
    self.response.headers['Last-Modified'] = Time.now.to_s

    self.response_body = Asdf.new                                                  
  end

  def before
    Rails.logger.info "before_filter called"
  end

  def after
    Rails.logger.info "after_filter called"
  end

end

示例日志输出（时间反映它正在流式传输）

Started GET "/welcome/index" for 192.168.74.64 at 2016-01-25 17:28:17 -0600
Processing by WelcomeController#index as HTML
before_filter called
around_filter prior to action
around_filter after action
after_filter called
Completed 200 OK in 0.7ms (ActiveRecord: 0.0ms)
STREAMING LINE 1
STREAMING LINE 2
STREAMING LINE 3
STREAMING LINE 4
STREAMING LINE 5

Answer 1

看起来，与其依赖around_filter，不如在迭代器耗尽后，您可以在类的each 方法中调用数据清理例程：

class Asdf
  def each
    (1..5).each do |num|
      sleep(1)
      Rails.logger.info "STREAMING LINE #{num}"
      yield "test#{num}\n"
    end
    Rails.logger.info "ALL DONE; READY TO CLEAN UP"
    clean_up
  end

  def clean_up
    Rails.logger.info "CLEANING UP"
  end
end

在 Rails 3.2 应用程序中点击 welcome#index 操作会在日志中产生以下内容：

Started GET "/welcome" for 127.0.0.1 at 2016-01-25 18:55:49 -0800
Processing by WelcomeController#index as HTML
before_filter called
around_filter prior to action
around_filter after action
after_filter called
Completed 200 OK in 0.5ms (ActiveRecord: 0.0ms)
STREAMING LINE 1
STREAMING LINE 2
STREAMING LINE 3
STREAMING LINE 4
STREAMING LINE 5
ALL DONE; READY TO CLEAN UP
CLEANING UP