How do you validate attachment_fu's image width and height?

Question

I want to be able to validate the image is exactly a certain with or a certain height, or if it's square.

In the validation block of the model that has_attachment, when I try to access image_size, width, or height, it always comes out as null.

I also asked the question here if you want more details.

Answer 1

Yea, you need to hack a bit in order to get it to work, but not so much. Adapting from attachment_fu's own image processor:

 validate :validate_image_size

  private

  def validate_image_size
    w, h = width, height

    unless w or h
      with_image do |img|
        w, h = img.columns, img.rows
      end
    end

    errors.add(:width, "must less than 250px")  if w > 250
    errors.add(:height, "must less than 250px")  if h > 250
  end
end