File Upload Indicator in Ruby on Rails Web Applications

Task: to show how to implement the file loading indicator for different configurations of Ruby on Rails:

I will divide the series of articles into three parts.

mongrel

mongrel (s) + nginx

mod_rails



The following are verified with:

Ruby on Rails 2.2.2

ruby 1.8.6 (2008-03-03 patchlevel 114) [universal-darwin9.0]

mongrel 1.1.5

Mac OS X 10.5.6



Part I. How to do it with mongrel

The basis of the article, the link to which is at the very end. But repeating it on my new rails and pollereha nothing happened. I changed her a little bit.



Creation of the frame:

rails upload

cd upload

rm public/index.html

script/generate controller home index upload progress

touch app/views/layouts/application.html.erb



')

Adding Routing:

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1. ActionController :: Routing :: Routes.draw do | map |
2. map.root: controller => 'home'
3. map.upload '/ upload' ,: controller => 'home' ,: action => 'upload'
4. map.progress '/ progress' ,: controller => 'home' ,: action => 'progress'
5. end

The preparation phase is complete. Now we need to explain a little how the file upload indicator functions. The form submission should go to the iframe, and from the page itself using ajax requests you can refer to a specific controller that will return the current state (you can in json, you can html, javascript is done here), and depending on them on the page move the indicator.



So, there is one controller, and there are three methods in it: index for outputting the form for upload, upload - processing the uploaded file, progress - for getting data on the status of the upload. The controller looks like this:

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1. class HomeController <ApplicationController
2. skip_before_filter: verify_authenticity_token,: only => [: progress ]
4. def index
5. @upid = Time .now.tv_sec.to_s
6. end
8. def upload
9. render: text => 'done'
10. end
12. def progress
13. @status = Mongrel :: Uploads.check (params [: upload_id])
14. respond_to do | format |
15. format .js
16. end
17. end
18. end

skip_before_filter is required since requests will go without a token. @upid is a unique identifier.

Now you need to write a plugin for Mongrel, which will intercept the download files (or rather, refer to a specific url) and store data on the download status, in addition, you need to somehow access this data. It's good that this is already implemented and the code can be taken from svn:



svn co svn://rubyforge.org/var/svn/mongrel/trunk/projects/mongrel_upload_progress



I propose to do this: create a file lib / progress_plugin.rb with the following contents:

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1. class Upload <GemPlugin :: Plugin "/ handlers"
2. include Mongrel :: HttpHandlerPlugin
4. def initialize (options = {})
5. @path_info = Array (options [: path_info])
6. @frequency = options [: frequency] || 3
7. @request_notify = true
8. if options [: drb]
9. require 'drb'
10. DRb.start_service
11. Mongrel .const_set: Uploads, DRbObject. new ( nil , options [: drb])
12. else
13. Mongrel .const_set: Uploads, Mongrel :: UploadProgress.new
14. end
15. Mongrel :: Uploads.debug = true if options [: debug]
16. end
18. def request_begins (params)
19. upload_notify (: add , params, params [ Mongrel :: Const :: CONTENT_LENGTH] .to_i)
20. end
22. def request_progress (params, clen, total)
23. upload_notify (( mark , params, clen)
24. end
26. def process (request, response)
27. upload_notify (: finish , request.params)
28. end
30. private
31. def upload_notify (action, params, * args)
32. return unless @path_info. include ? (params [ 'PATH_INFO' ]) &&
33. params [ Mongrel :: Const :: REQUEST_METHOD] == 'POST' &&
34. upload_id = Mongrel :: HttpRequest.query_parse (params [ 'QUERY_STRING' ]) [ 'upload_id' ]
35. if action ==: mark
36. last_checked_time = Mongrel :: Uploads. last_checked (upload_id)
37. return unless last_checked_time && Time .now - last_checked_time> @frequency
38. end
39. Mongrel :: Uploads.send (action, upload_id, * args)
40. Mongrel :: Uploads. update_checked_time (upload_id) unless action ==: finish
41. end
42. end
44. # Keeps track of the status of all currently processing uploads
45. class Mongrel :: UploadProgress
46. attr_accessor: debug
47. def initialize
48. @guard = Mutex .new
49. @counters = {}
50. end
52. def check (upid)
53. @counters [upid] .last rescue nil
54. end
56. def last_checked (upid)
57. @counters [upid] .first rescue nil
58. end
60. def update_checked_time (upid)
61. @ guard.synchronize {@counters [upid] [ 0 ] = Time .now}
62. end
64. def add (upid, size)
65. @ guard.synchronize do
66. @counters [upid] = [ Time .now, {: size => size,: received => 0 }]
67. puts "# {upid}: Added" if @debug
68. end
69. end
71. def mark (upid, len)
72. return unless status = check (upid)
73. puts "# {upid}: Marking" if @debug
74. @ guard.synchronize {status [: received] = status [: size] - len}
75. end
77. def finish (upid)
78. @ guard.synchronize do
79. puts "# {upid}: Finished" if @debug
80. @counters. delete (upid)
81. end
82. end
84. def list
85. @ counters.keys.sort
86. end
87. end

After that, create a config for mongrel (in fact, a normal ruby-file), which will connect this plugin to mongrel:

touch config/mongrel_upload_progress.conf





Put in mongrel_upload_progress.conf you need the following:

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1. require 'progress_plugin'
2. uri "/" ,: handler => plugin ( '/ handlers / upload' ,: path_info => '/ upload' ),: in_front => true

path_info is a route that will be intercepted by the plugin to track the status of the download.

Download form and all the necessary js-nicks can be taken here .



It remains to just run the mongrel with the configuration file:

mongrel_rails start -S config/mongrel_upload_progress.conf





The indicator in the browser will look something like this:



If there are several mongrelians you can use drb, the details are described in the link below.



I did not make any cosmetic changes within this article. In a more beautiful form, the indicator can be viewed on rghost.ru



Of course, it is a pity to admit that all this is written most likely in vain, since few people are just getting along with a simple mongrel. Usually they put nginx in front of the mongrel or even replace it with apache with mod_passenger. I plan to write articles about them later.

References

mongrel upload progress