如何從模型中檢查ActiveRecord中是否存在關聯？

Question

我嘗試了所有可以在網上找到的組合，但總是失敗。

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 

裏面的資料模式，我嘗試做：

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

    end 

Answer 1

通過the blog post that Olivier linked to和confirmed in the Sunspot documentation的啓發，你可以這樣做：

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