title: How to skip association callback in destroy
body: <p>In my project, discount has and belongs to many businesses. I have an association callback rule that a discount can't remove its last businss (to maintain that there is always a businss for each discount):</p>
  
  <pre><code>has_and_belongs_to_many :businesses,
    before_remove: :check_count,
  
  def check_count
    raise 'Cannot remove latest business!' if businesses.count == 1
  end
  </code></pre>
  
  <p>However I realized that I won't be able to remove discounts. Since when I do <code>discount.destroy</code>, I think it will try to remove businesses, and in term will raise the error.</p>
  
  <p>So is there a way around this, like some kind of <code>:except</code> as in controllers?</p>