Ruby on rails rails名称空间模型-关联

当我尝试使用has_many:through关联时，它似乎在联接表中查找泛型键。范例

class Ots::Foo < ActiveRecord::Base
  has_many :foo_bars, :class_name => '::Ots::FooBar', :foreign_key => :ots_foo_id
  has_many :bars, :class_name => '::Ots::Bar', :through => :foo_bars
end

class Ots::Bar < ActiveRecord::Base
  has_many :foo_bars, :class_name => '::Ots::FooBar', :foreign_key => :ots_bar_id
  has_many :bars, :class_name => '::Ots::Bar', :through => :foo_bars
end

class Ots::FooBar < ActiveRecord::Base
  belongs_to :foo, :class_name => "::Ots::Foo", :foreign_key => :ots_foo_id
  belongs_to :bar, :class_name => "::Ots::Bar", :foreign_key => :ots_bar_id
end

f = Foo.find(1)
f.bars  =># invalid column name 'bar_id'

这是我应该期待的吗？有没有更优雅的名称空间解决方案