Trying to create a Mongoid document from params received through ActiveMerchant

ActiveMerchant Mongoid

class Donation
  include Mongoid::Document
  field :success, :type => String
  field :authorization, :type => String
  field :message, :type => String
  field :params, :type => Hash, :default => {}
  
  def response=(response)
    self.success        = response.success?
    self.authorization  = response.authorization
    self.message        = response.message
    self.params         = response.params
  rescue ActiveMerchant::ActiveMerchantError => e
    self.success       = false
    self.authorization = nil
    self.message       = e.message
    self.params        = {}
  end
end

I tried it out locally and am seeing the same behavior you are. It looks like it might be a bug in Mongoid.