Carrierwave how to get the file extension

Question

I'm developing a Ruby on Rails application that requires file uploading/downloading. For the upload part i used the gem carrierwave since it's very easy to use and flexible. The problem is: once i uploaded the file, i need to know a few things: i.e. if it's a pdf instead of downloading the file i show it inline,and the same goes for an image. How do i get the file extension and how can i do it to send the file to a user?? Any feedback is appreciated Thanks!!

score 40 · Accepted Answer · answered Jul 25 '12 at 08:32

40

Determine file extension (I suppose a name for mounted uploader is 'file'):

file = my_model.file.url
extension = my_model.file.file.extension.downcase

Then prepare mime and disposition vars:

disposition = 'attachment'
mime = MIME::Types.type_for(file).first.content_type

if %w{jpg png jpg gif bmp}.include?(extension) or extension == "pdf"
  disposition = 'inline'
end

(add other extensions if you want).

And then send the file:

send_file file, :type => mime, :disposition => disposition

answered Jul 25 '12 at 08:32

bender

1,430
10
14

Thank you very much, i like the style of your solution, and it worked perfectly. Again, thanks for the reply!! – Wiggin Jul 25 '12 at 09:19
where exactly in the rails project files you place the disposition and MIME type vars? – maumercado Oct 12 '12 at 02:02

Stefan Kanev · Answer 2 · 2012-07-25T09:16:00.513

5

Once you have uploaded a file, the name is stored in the database. This also includes the extension. Assuming you have a User model with an uploader mounted as asset, then you can get it as:

user.asset.file.extension

As for sending it to the user, if you call user.asset_url, it will give you the URL where the file is uploaded. The user can use that link to get the file. Or am I misunderstanding what you mean by "send the file to a user"?

edited Jul 25 '12 at 09:16

answered Jul 25 '12 at 08:30

Stefan Kanev

3,030
22
17

Thanks for replying!! well, i want to make the user download the file. You know, donwload dialog (open with.. or keep it or in chrome case keep or reject.)I thought that with a simple send_file with parameters would be okay. – Wiggin Jul 25 '12 at 08:57
Well, just link to the file then. You can get the url with `user.asset_url`. – Stefan Kanev Jul 25 '12 at 09:15
Yup, i did it! your advise worked perfectly, thanks so much!! – Wiggin Jul 25 '12 at 09:19
when in context of an uploader all you need to call is `file.extension` e.g. in `def filename; ["original", file.extension].join('.'); end` – equivalent8 Aug 16 '21 at 14:52

Carrierwave how to get the file extension

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