Paperclip by default try to process every image file to generate thumbnail. But it also try to do it with pdf files, which can be really time consuming task. I tried looking on google and found one solution, but it changes Paperclip methods.
How to disable pdf postprocessing in Paperclip without changing Paperclip sources?
One solution is to use before_post_process callback:
# Model with has_attached_file
before_post_process :forbid_pdf # should be placed after line with has_attached_file
private
def forbid_pdf
return false if (data_content_type =~ /application\/.*pdf/)
end
data_content_type should be changed to corresponding field in your model.
Another solution I came up with is to create custom processor for images in which we should check file type and if it is not pdf run standard processor Paperclip::Thumbnail.
From my current production app, similar to above, but explicitly looks for images (in this case my uploader pretty much accepts any type of file, so I process only images and ignore all others):
before_post_process :is_image?
def is_image?
["image/jpeg", "image/pjpeg", "image/png", "image/x-png", "image/gif"].include?(self.asset_content_type)
end