思考Sphinx和范围的问题

Question

现在几个小时我试图让sphinx示波器工作失败。

我想要范围ActsAsTaggableOn的标签。在我的模型中（可标记）我尝试了以下范围：

# This normal scope works
scope :tagged, lambda {
  joins(:taggings => :tag).
  where("tags.name = 'consequatur'")
}

# fails! (can't convert ActiveRecord::Relation into Hash)
sphinx_scope :tagged do
  joins(:taggings => :tag).
  where("tags.name = 'consequatur'")
end

对旧条件的另一次尝试：

# works with normal scope (returns one record)
scope :tagged, :joins => :taggings, :conditions => {"taggings.tag_id" => 74}

# fails! (returns nothing)
sphinx_scope(:tagged) do
  {:joins => :taggings, :conditions => {"taggings.tag_id" => 74}}
end

如何使这些范围有效？是否有其他方式来存档该任务？我想只搜索那些用特定标签标记的模型。