old-roraccounting/app/models/money_move.rb

class MoneyMove < ApplicationRecord
  belongs_to :homie

  def create_move(params)
    common_params = { description: params[:description] } 

    move_from = MoneyMove.new(
      common_params + { 
        homie_id: params[:from_homie_id],
        amount: -BigDecimal.new(params[:amount])   
      } 
    )
    move_to = MoneyMove.new(
      common_params + { 
        homie_id: params[:from_homie_id],
        amount: BigDecimal.new(params[:amount])
      }
    )

    MoneyMove.transaction do 
      move_from.save!
      move_to.save!
    end
  end
end