gistfile1.rb

class User < ActiveRecord::Base
  has_many :events, :extend => AssociationDefaultAttributes do
    def default_attributes
      { :venue => proxy_owner.default_venue }
    end
  end
end

module AssociationDefaultAttributes
  def create(attrs, &block)
    super(default_attributes.merge(attrs), &block)
  end

  def build(attrs={}, &block)
    super(default_attributes.merge(attrs), &block)
  end
end