Rails - Jan 2006 - Strange thing with ActiveRecord ??

Hi

I am probably missing something, so please help:

I have a table called ''zipped_responses'' with an
''item_names'' varchar column.

I want to create a comma separated string of ''names''.
I have an ''add_item_names'' method which takes a
''name'' and put it at the end
of a string with a preceding comma.  

The model goes like this:

class ZippedResponse < ActiveRecord::Base	
		
	def add_item_names (name)		
	  str = read_attribute(:item_names)   
	  str << "," unless str.empty?
          str << name	
	  write_attribute(:item_names, str)
	end
			
end

Now in the console, I write

z=ZippedResponse.new
z.add_item_names("aa")

and I get:
z.item_names => "aa"

Fine until here. Now I write:

z1=ZippedResponse.new

and to my suprise I get that in z1, the ''item_names'' attribute
has also the
value "aa" !!
(z1.item_name => "aa")

How come ??

Nadav