Rails ActiveRecord查询（交叉模型）

Question

I have an app that lets users input dates & interests that relate to those dates .I need to send them deals (a few days before the date - Via Email) that are based off of their interests and location. I have all the models setup and recording the data properly, just wondering how to query the models for the dates and then send the appropriate deal based off of the city and interests.

Notes:

*Each city and interest category has only 1 deal

*I have several different models for types of dates (Holidays, Occasions, Friends Birthdays ect).. all are pretty much identical in structure.

*All interests for each type of date are stored in person_interests.

    Models:

    Class User
      belongs_to :province
      belongs_to :city
      has_many :friends_bdays
      has_many :occasions
      has_many :person_interests, :as => :person
      has_many :interests, :through => :person_interests
      has_many :user_holidays
      has_many :holidays, :through => :user_holidays
      has_many :anniversaries
    end

    class Deal < ActiveRecord::Base
       belongs_to :interest
       belongs_to :city
       belongs_to :store  
    end

   class Store < ActiveRecord::Base
      has_many :deals
      belongs_to :city
      belongs_to :province
    end

    class PersonInterest < ActiveRecord::Base
      belongs_to :interest
      belongs_to :person, :polymorphic => true  
    end

    class Interest < ActiveRecord::Base
      has_many :person_interests
      has_many :deals
    end


    class Occasion < ActiveRecord::Base
      belongs_to :user
      belongs_to :admin_user
      has_many :person_interests, :as => :person
      has_many :interests, :through => :person_interests    
    end


    class Anniversary < ActiveRecord::Base
      belongs_to :user
      has_many :person_interests, :as => :person
      has_many :interests, :through => :person_interests
    end


  class Friend_bday < ActiveRecord::Base
    belongs_to :user
    has_many :person_interests, :as => :person
    has_many :interests, :through => :person_interests
  end

Answer 1

You can achieve this using a variation of the solution below:

Install the squeel gem

class User
  def deals(reload=false)
    @deals = nil if 
    @deals ||= Deal.where{ 
     ( (:city => city_id) | ( :interest_id => interest_ids) ) & 
     :deal_date => (Time.now..3.days.from_now) 
    }
  end
end

Now, user.deals returns the deals that will be active in next 3 days matching the user's city OR interests.

Edit 1:

Based on your comment it looks like you don't need the squeel gem. You can achieve what you want using regular AR syntax.

class User
  def deals(reload=false)
    @deals = nil if reload

    @deals ||= Deal.where(
      :city => city_id, 
      :interest_id => interest_ids, 
      :deal_date => (Time.now..3.days.from_now) 
    )
  end
end