# Is it possible to determine the file size before an actual u **URL:** \ **Category:** Rails\ **Created:** [March 14, 2007, 8:05pm UTC](https://www.ruby-forum.com/t/is-it-possible-to-determine-the-file-size-before-an-actual-u/88829 "2007-03-14T20:05:59Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![dan\_kuwachi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/dfb087/32.png) [@dan\_kuwachi](https://www.ruby-forum.com/u/dan_kuwachi)\ **Post date:** [March 14, 2007, 8:05pm UTC](https://www.ruby-forum.com/t/is-it-possible-to-determine-the-file-size-before-an-actual-u/88829/1 "2007-03-14T20:05:59Z")
I am doing a file upload where I want to constrain the maximum size to 1 mb, and I can check this data after the upload has completed. Is there a way to check this before the upload actually starts? ---
**Author:** ![dan\_kuwachi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/dfb087/32.png) [@dan\_kuwachi](https://www.ruby-forum.com/u/dan_kuwachi)\ **Post date:** [March 14, 2007, 8:13pm UTC](https://www.ruby-forum.com/t/is-it-possible-to-determine-the-file-size-before-an-actual-u/88829/2 "2007-03-14T20:13:27Z")
dan kuwachi wrote: > I am doing a file upload where I want to constrain the maximum size to > 1 mb, and I can check this data after the upload has completed. Is > there a way to check this before the upload actually starts? I don’t think you can do this. Rails will not even begin processing the action until the browser finishes sending the request. And the file upload is part of the request. I think you are at the mercy of HTTP here. But I could be completely wrong since I have heard of rails based file upload progress bars, so if anyone knows better feel free to shoot me down. ---
**Author:** ![dan\_kuwachi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/dfb087/32.png) [@dan\_kuwachi](https://www.ruby-forum.com/u/dan_kuwachi)\ **Post date:** [March 15, 2007, 1:45am UTC](https://www.ruby-forum.com/t/is-it-possible-to-determine-the-file-size-before-an-actual-u/88829/3 "2007-03-15T01:45:45Z")
If you’re using mongrel, you can write a handler to get information about the incoming request before it’s completely downloaded. You can then have your rails controllers connect to the handler via drb to get the content-length information the browser sends. Afaik, this is what mongrel’s upload progress handler does: [http://mongrel.rubyforge.org/docs/upload\_progress.html](http://mongrel.rubyforge.org/docs/upload_progress.html) It’ll probably do what you need to do. If not, you can use it as inspiration for your own handler.