Rails 2. Calling virtual attribute's setter by update_attributes

Question

I have one extra attribute in my form (:pagesize) which is not in database. There is also a setter for it:

def pagesize= pagesize
  self.preferences["pagesize"] = pagesize
end

I want 'update_attributes' method to call that setter. What is the best type for :pagesize attribute? attr_accessor, attr_writer...

Answer 1

If that attribute is not defined in your model, you can just define the setter, and then do whichever logic you want:

class YourModel < ActiveRecord::Base

  attr_writer :pagesize

  def pagesize=(val)
    self.size_of_page = val
  end

end

something like this. I wrote the AR version because I assumed you are using it, but the principle is the same for DataMapper or mongoid.

Answer 2

u can call update_attributes on a attr_accessor variable but it needs to be defined as accessible. Also, if u define the variable as attr_writer, u dont need to define a setter method since its added in the backend. Checkout Why use Ruby's attr_accessor, attr_reader and attr_writer? for more info