Question

When I upload a photo to my Rails application using PaperClip how can I know the dimensions (width & Height) of it?

Answer 1

http://rdoc.info/github/thoughtbot/paperclip/master/Paperclip/Geometry

In your model:

before_save :set_dimensions

def set_dimensions
  tempfile = self.local_avatar.queued_for_write[:original]

  unless tempfile.nil?
    dimensions = Paperclip::Geometry.from_file(tempfile)
    self.width = dimensions.width
    self.height = dimensions.height
  end
end

You need to change local_avatar. And have width and height column in your model.

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