Rails 3 Attribute Validation

I didn't do much with these JQuery-tokeninput or Rails virtual attributes, but I hit my head against the wall. Any help or guidance is appreciated.

I have a virtual attributes reader in my ad model where I need to check for existence:

attr_reader :classroom_tokens
validates :classroom_tokens, :presence => true``

      

        
        
        
      

    

followed by a getter and setter:

def classroom_tokens=(ids)
    self.classroom_tokens = ids.split(",")
end

def classroom_tokens
    #Tried several things here
end 

      

        
        
        
      

    

I just need to make sure the [: announcement] [: classroom_tokens] parameters are not empty. The called validator seems to be looking at something else as it is always empty no matter what. What am I missing? Any help is appreciated.

Rails 3.1 Ruby 1.9.2

UPDATE: If I do

#Announcement MODEL
attr_reader :classroom_tokens
#validates :classroom_tokens, :presence => true
def classroom_tokens=(ids)
  @classroom_tokens = ids.split(",")
end

#Announcement_controller create action
puts "Token=>#{@announcement.classroom_tokens}|"
puts "Params=>#{params[:announcement][:classroom_tokens]}|" 

      

        
        
        
      

    

I get:

Token=>|
Params=>7,13,12|