Question

Paperclip initializes styles before form parameters are processed, thereby ignoring my attempt to specify a custom resize.

Model:

    attr_accessor :new_width, :new_height        

    has_attached_file :attachment,
      styles: lambda { |attachment| attachment.instance.set_styles }
      ...

    def set_styles
      # Default thumb:
      styles = { thumb: '100x100>' }

      # Resize original if new sizes have been specified
      if new_width and new_height
        styles[:original] = "#{new_width}x#{new_height}>"
      end

      styles
    end

I can see through the log files that styles are defined and the convert command triggers before new_width and new_height are assigned the values passed by the controller.

Rails server log file:

    {:thumb=>"100x100>"} # logger.info in the model
    ...
    # Command :: convert ... etc
    # [paperclip] Saving attachments.
    ...
    {:thumb=>"100x100>", :original=>"300x300>"}  # logger.info in the model

By the time the custom dimensions are assigned to the instance, the ImageMagick command has already been triggered by Paperclip.

How can I pass custom dimensions to Paperclip to define the styles before the image is processed?

Answer 1

Have you tried using a callback in your model to calculate the width and height before saving the model?

before_save :set_styles

From the paperclip documentation on attachments, the paperclip attachment saves when the model saves and process the file upon assignment.