ruby-on-rails - Creating a nested model for "new" action in a controller

Question

I have a model:

class MyModel < ActiveRecord::Base
  attr_accessible #.....

  belongs_to :owner
end

And there is a controller's action:

  def new
    @data1 = MyModel.new
  end

And a view:

= f.select :owner_id, options_from_collection_for_select(MyModel.some_scope, :id, :full_name, @data1.owner.id)

Obviously, @data1.owner.id is empty. How do I make it "non-empty"?