ruby-on-rails - 查找具有非空字段的所有记录？

Question

我试图定义两个变量，如下所示:

@orders = Customer.find_all_by_order_date(nil)

@nonorders = Customer.find_all_by_order_date(!nil)

第一个可以正常工作，但是第二个则不能。我如何找到那些order_date字段不是nil的客户？

@nonorders = @customer.orders.find(:all, :conditions => "@customer.orders.order_date IS NOT NULL")

给我以下错误:
undefined method 'extract_options_from_args!' for ActiveRecord::Base:Class
我尝试更改条件，例如 @orders.order_date， @customer.order.order_date等。是什么导致此错误？谢谢!

Answer 1

Rails3:

@nonorders = Customers.where("customers.date IS NOT NULL")

Rails2:

@nonorders = Customers.find(:all, :conditions => "customers.date IS NOT NULL")