使用动态查找器指定不是null

Question

我经常想使用动态发现器来指定不是null。所以…

这起作用：

Widget.find_all_by_color('blue')

这起作用：

Widget.find_all_by_color(nil)

但是我该怎么办

SELECT * FROM `widgets` WHERE `color` IS NOT NULL;

?

Answer 1

试试这个：

Widget.all(:conditions => "color IS NOT NULL")

Answer 2

两种方式取决于您想要的特定程度：

# in your model
class Widget < ActiveRecord::Base
  # first way
  named_scope :coloured, {:conditions => ["color IS NOT NULL"]}
  # second way
  named_scope :not_null, lambda{|*args| (field=args.first ? {:conditions => ["#{field} is not null",field]} : {}) } }
end

# in your controller
@coloured_widgets = Widget.coloured.all           # using first way
@coloured_widgets = Widget.not_null(:colour).all  # using second way

我希望它有帮助。

干杯

Answer 3

Widget.find(:all, :conditions => "color IS NOT NULL")

Answer 4

不太优雅，但这应该奏效：

Widget.find(:all, :conditions => "'color' IS NOT NULL")