```ruby
require 'paperclip'

class WikiPageAttachment < ActiveRecord::Base
  acts_as_wiki_page_attachment do
    has_attached_file :wiki_page_attachment, :styles => { :medium => "300x300>", :thumb => "100x100>" },
      :storage => :s3,
      :s3_credentials => "#{Rails.root}/config/s3.yml",
      :s3_host_alias => CONFIG.s3_bucket,
      :bucket => CONFIG.s3_bucket,
      :path => "wiki_page_attachments/:id-:style.:extension",
      :url => ":s3_alias_url"
    validates_attachment_presence :wiki_page_attachment, :message => " is missing."
    validates_attachment_content_type :wiki_page_attachment, :content_type => ['image/jpeg','image/jpg','image/png','image/x-png','image/gif','image/pjpeg'], :message => ' must be a JPEG, PNG or GIF.'
  end
end
```

Allow PDF attachments for wiki pages.
user
```ruby
require 'paperclip'

class WikiPageAttachment < ActiveRecord::Base
  acts_as_wiki_page_attachment do
    has_attached_file :wiki_page_attachment, :styles => { :medium => "300x300>", :thumb => "100x100>" },
      :storage => :s3,
      :s3_credentials => "#{Rails.root}/config/s3.yml",
      :s3_host_alias => CONFIG.s3_bucket,
      :bucket => CONFIG.s3_bucket,
      :path => "wiki_page_attachments/:id-:style.:extension",
      :url => ":s3_alias_url"
    validates_attachment_presence :wiki_page_attachment, :message => " is missing."
    validates_attachment_content_type :wiki_page_attachment, :content_type => [
      'image/jpeg',
      'image/jpg',
      'image/png',
      'image/x-png',
      'image/gif',
      'image/pjpeg',
      'application/pdf'
    ], :message => ' must be a JPEG, PNG , GIF, or PDF.'
  end
end
```
assistant