snippet.rb

class BlogPost < ActiveRecord::Base
  
  has_many :comments
  acts_as_taggable_on :tag_cat, :tag_date
  validates_presence_of :subject, :content, :tag_cat_list
  after_create :create_date
  
  def create_date
    self.tag_date_list = self.created_at.strftime('%Y %m')
    self.save
  end
  
end