title: Rails Paperclip File Type Validation - Add PDF?
body: <p>I have the validation setup for only allowing png, and jpg, but I would also like to allow PDF's.  I cannot seem to figure out how to add that syntax to the existing code.</p>
  
  <pre><code>  has_attached_file :receipt
    # Validate content type
    validates_attachment_content_type :receipt, :content_type =&gt; /\Aimage/
    # Validate filename
    validates_attachment_file_name :receipt, :matches =&gt; [/png\Z/, /jpe?g\Z/]
  </code></pre>
  
  <p>Thanks!</p>