are serialized fields required?

When I specify that a field is serialized in the model, but create an object of that model without the (optional) serialized field, I run into problems that seem to indicate serialized fields are required. It seems to be taking the nil value of the field and trying to unserialize it, unsuccessfully.

So, in my model: class Person < ActiveRecord::Base   serialize :research_discipline, Array

When I do this: member = Member.new # Member subclasses Person assert !member.valid?

I get: ActiveRecord::SerializationTypeMismatch: research_discipline was supposed to be a Array, but was a NilClass

So can I have an optional serialized field?

Thanks, Julia

Well I haven't gotten a reply, but I did find this relevant patch, which was submitted a few days ago: http://dev.rubyonrails.org/ticket/7293

Julia