gistfile1.rb

  def assign_tags(tags)
    tags.split(',').collect {|t| t.strip}.uniq.each do |tag|
      thistag = Tag.first_or_create(:name => tag.downcase)
      PostTagging.create(:post_id => self.id, :tag_id => thistag.id)
    end
  end
  
  def update_tags(tags)
    self.post_taggings.each { |tagging| tagging.destroy }
    self.post_taggings.reload
    tags.split(',').collect {|t| t.strip}.uniq.each do |tag|
      thistag = Tag.first_or_create(:name => tag.downcase)
      PostTagging.create(:post_id => self.id, :tag_id => thistag.id)
    end
  end