gistfile1.rb

# ORIGINAL METHOD
def change_owner
    @shared_expense = SharedExpense.find(params[:id])
    current_owner = @shared_expense.user
    roomies = @shared_expense.dwelling.roomies.sort_by { |roomie| roomie.id }
    next_owner_index = roomies.index {|roomie| roomie.id == current_owner.id} + 1
    next_owner = roomies[next_owner_index]
    @shared_expense.user_id = next_owner.id
    @shared_expense.save
    redirect_to current_user.dwelling
end

# REFACTORED METHOD
def change_owner
    @shared_expense = SharedExpense.find(params[:id])
    current_owner = @shared_expense.user
    roomies = @shared_expense.dwelling.roomies.sort_by { |roomie| roomie.id }
    next_owner_index = roomies.index {|roomie| roomie.id == current_owner.id} + 1
    @shared_expense.user_id = roomies[next_owner_index].id
    @shared_expense.save
    redirect_to current_user.dwelling
  end