How in Ruby on Rails 4.2.6 make a statement which has to check for file extension and upload to right public folder - ruby-on-rails

Question

I'm working on an application which has an upload functionality for documents. I can download various kind of documents like pdf, docx and etc. However, all is uploaded in one folder like ../uploads/documents.
What I have to reach is when the upload began, a statement will check the file extension and upload it to the right folder named as the extension of the file. As an example, I can have a PDF in upload and the app check if the PDF directory exists and if not create one, then upload to that directory. So far I have done what below but I'm new in RoR so I would like to have some suggestions how to make what mentioned above:
This comes from my CTRL:
module UploaderWidget
class Engine < ::Rails::Engine
end
def initialize(params = {})
#file = params.delete(:file)
super
if #file
self.filename = sanitize_filename(#file.original_filename)
self.content_type = #file.content_type
self.file_contents = #file.read
end
end
def upload_local
path = "#{Rails.root}/public/uploads/document"
FileUtils.mkdir_p(path) unless File.exists?(path)
FileUtils.copy(#file.tempfile, path)
end
private
def sanitize_filename(filename)
return File.basename(filename)
end
def document_file_format
unless ["application/pdf","application/vnd.ms-excel",
"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
"application/msword",
"application/vnd.openxmlformats-officedocument.wordprocessingml.document",
"text/plain", "text/csv", "application/octet-stream"].include? self.content_type
errors.add(:file, 'Invalid file format.')
end
end
NUM_BYTES_IN_MEGABYTE = 1048576
def file_size_under_one_mb
if (#file.size.to_f / NUM_BYTES_IN_MEGABYTE) > 1
errors.add(:file, 'File size cannot be over one megabyte.')
end
end
end

Answer 1

You can use the File.extname() method:
File.extname("test.rb") #=> ".rb"
File.extname("a/b/d/test.rb") #=> ".rb"
File.extname("foo.") #=> ""
File.extname("test") #=> ""
File.extname(".profile") #=> ""
File.extname(".profile.sh") #=> ".sh"
In your particular case, you could do something like this:
sanitize the file name and save it to an instance variable
extract the extension name and save it to an instance variable
eventually manipulate your extension name, e.g.
remove the '.' char
create an hash having every extension as a key and the sub-folder name as a value
define a method to manipulate the extension and return the folder name
build your path like path = Rails.root.join('public', 'uploads', 'document' sub_folder_name)
The rest of your code should work as it is