不能对符号使用条件。DataMapper with Sinatra

Question

尝试在datamapper中使用符号上的条件时，我会遇到麻烦：

 clusters = Cluster.all(:latitude.not => nil)

此代码引发错误：

ArgumentError - condition #<Origin::Key:0x50d05a0 @name=:latitude, @strategy=:__override__, @operator="$not", @expanded=nil, @block=
nil> of an unsupported object Origin::Key:
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/query.rb:888:in `block in assert_valid_conditions'
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/query.rb:853:in `each'
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/query.rb:853:in `assert_valid_conditions'
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/query.rb:776:in `block in assert_valid_options'
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/query.rb:766:in `each'
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/query.rb:766:in `assert_valid_options'
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/query.rb:363:in `update'
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/query.rb:386:in `merge'
        C:/Ruby21/lib/ruby/gems/2.1.0/gems/dm-core-1.2.1/lib/dm-core/model.rb:767:in `scoped_query'

集群模型类：

class Cluster
  include DataMapper::Resource
  property :id,               Serial
  property :city_id,          Integer
  property :name,             String
  property :latitude,         Float
  property :longitude,        Float      
end

我正在使用的核心宝石版本：sinatra-1.4.6，data_mapper-1.2.0。

此代码可能是什么问题？无法解决此错误。

Answer 1

您可以做这样的事情：

clusters = Cluster.all - Cluster.all(:latitude => nil) 

参考（结合查询13）