查RDoc手册,
- << :附加一个对象;
- concat:附加一个或多个对象;
由于我没有搞清楚这个概念,今天频频跳出这个错误:
NoMethodError (undefined method `province_id' for #<Class:0x57bb984>):
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/base.rb:1672:in `method_missing_without_paginate'