Datamapper是非NULL查询

Question

如何编写activerecord语句,

Comments.where("attachment IS NOT NULL")

在DataMapper中

即,我想"SELECT * FROM comments WHERE attachment IS NOT NULL;在rails中使用DataMapper 执行.

请帮忙; 我对DM不太熟悉!

Answer 1

使用旧的AR 2.3语法应该适合您

Comment.all(:conditions => 'attachment IS NOT NULL')

或者,您可以使用not符号上可用的方法进行DataMapper查询:

Comment.all(:attachment.not => nil)