如何从模型中检查ActiveRecord中是否存在关联？

Question

我尝试了所有可以在网上找到的组合，但总是失败。

class Profile < ActiveRecord::Base 

    belongs_to :user, :dependent => :destroy 
    has_one  :match # educational matches 

    accepts_nested_attributes_for :match 
    attr_accessor     :form 

    unless match.present? 
    searchable do 

     integer :id 
     string :country 
     string :state 
    end 
    end 
end 

和

Match belongs_to :profile 

里面的资料模式，我尝试做：

unless profile.match.exist? (does profile have a match association existing?) 
    .. do something 

    end 

Answer 1

通过the blog post that Olivier linked to和confirmed in the Sunspot documentation的启发，你可以这样做：

# In your Profile model 
searchable :if => proc { |profile| profile.match.present? } do 
    integer :id 
    string :country 
    string :state 
end