Administarte gem custom getter and setter

Question

I want to convert dollars to cents without using money gem and outside the model. This attribute belongs to model that is has a dashboard in Administrate gem.

When users input 10 it should be converted to cents as 10 * 100 and saved to DB. I was trying to do it using administrate custom Field then setup getter and setter, but it doesn't work:

class ConvertToCentsField < Administrate::Field::Base
  def to_s
    data
  end

  def buyer_fee_fixed
    @resource.buyer_fee_fixed
  end

  def buyer_fee_fixed=(value)
    @resource.buyer_fee_fixed = (value.to_f * 100).to_i
  end
end

Maybe I'm using getter and setter in the wrong place.