validates_attachment_content_type isn't accepting .tmTheme files (Sublime Text color schemes)

Question

I'm attempting to use a form to upload and store Sublime Text themes in a database.

It works fine with images, but replacing the content_type with the one applicable to Sublime Text theme files consistently tells me that the file "has contents that are not what they are reported to be"

class Color < ActiveRecord::Base
    has_attached_file :file
    validates_attachment_content_type :file, :content_type => ["image/png"]
end

Works fine

class Color < ActiveRecord::Base
    has_attached_file :file
    validates_attachment_content_type :file, :content_type => ["application/xml"]
end

Does not

Answer 1

I think you might need to tell Paperclip (I'm assuming that's what you are using) that 'tmtheme' is a valid extension by adding this to your config/environments/development.rb and config/environments/production.rb:

Paperclip.options[:content_type_mappings] = {
  :tmtheme => "application/xml"
}