Improved one base on condition, bad coding but it's work

models.rb

# Improved one base on condition, bad coding but it's work!
def number_list=(numbers_string)
    self.numbers.destroy_all
    numbers = numbers_string.split(",").collect{|num| num.strip.downcase}.uniq
    numbers.each do |number|
     unless !self.save
        num = self.numbers.find_or_create_by_content(number)
       end   
    end
  end