conditional convert options paperclip

note: haven't verified that on working code

It seems that the argument to the block passed in :convert_options is already an instance, not the attachment (as opposed to styles option, where it is an attachment)

Try:

convert_options: lambda { |instance| instance.decide_convert_options }

Btw your code would look much better if you extract the configuration data, for example:

has_attached_file :image,
  styles: lambda { |attachment| attachment.instance.image_options[:styles] }, 
  convert_options: lambda { |instance| instance.image_options[:convert_options] }


IMAGE_OPTIONS = {
  poster: {
    styles: {
      thumb: ["30x45!", :jpg],
      standard: ["185x278!", :jpg],
      expanded: ["372x559!", :jpg]
      big: ["600x900!", :jpg]
    },
    convert_options: {
      thumb: "-flop",
      standard: "-flop",
      expanded: "-flop",
      big: = "-flop"
    }
  },
  cover: {
    styles: {
      thumb: ["30x45!", :jpg],
      standard: ["300x1200!", :jpg]
    },
    convert_options: {
      thumb: "-enhance",
      standard: "-enhance"
    }
  }
}

def image_options
  IMAGE_OPTIONS[self.image_class]
end

I hope that helps

Update:

it looks like your convert_options are not being set here: https://github.com/thoughtbot/paperclip/blob/a93dfc773b4fd649db4d1281b42a2a71b1ae72ff/lib/paperclip/style.rb#L55

it seems they recommend passing convert_options with styles, like in this spec: https://github.com/thoughtbot/paperclip/blob/263a498195d47563a6227be18cf4463c4c6e7903/spec/paperclip/style_spec.rb#L41

can you try this? so remove convert_options entirely, and in your configuration return hash like:

IMAGE_OPTIONS = {
      poster: {
        styles: {
          thumb: {
            geometry: "30x45!",
            format: :jpg,
            convert_options: '-flop',
          },
          standard: {...}
          expanded: {...}
          big: {...}
        }
      },
      cover: {
        styles: {...}

Apply it to all since that's what you're doing anyway?

:convert_options => {:all => "-flop"}

failing that you might be looking at creating a Paperclip Processor

The approved answer doesn't work. It can be read in the comments and the author acknowledges that it hasn't been tested in code.

This code does work:

has_attached_file :image,
                  :styles => lambda { |attachment|

                    thumb_convert_options = case attachment.instance.image_class
                      when "poster"
                        "-flop"
                      when "cover"
                        "-enhance"
                    end

                    {
                      thumb: {
                        convert_options: thumb_convert_options
                      }
                    }
                  }

The correct approach is to have convert_options inside the styles lambda; having it as a separate lambda does not work, at least for Paperclip version 4.1 and higher.

To keep my answer in one place, I've put all the code inline and omitted all styles beside thumb. Obviously to implement this you should keep the method decide_convert_options.