How would I construct this validation rule?

rubyonrails-talk
1

Hi, I have this model,

class EcOrder < ActiveRecord::Base         has_many :ec_line_items         validates_associated :ec_line_items         ... end

and what I want to do is construct a validation rule that says an order is not valid unless it has one or more line items. The error message would read, "An order must have at least one item." How would I construct such a rule?

Thanks, - Dave