ruby-on-rails - 複雑な ActiveRecord クエリ

Question

このクエリの作成方法に頭を悩ませています。一連のスコープを作成してそれらを連鎖させようとする必要があるかどうかはわかりません。それともクラスメソッドに入れますか？または、両方のコンボを行いますか？誰かが私に短い例を与えることができれば、それは私が窓から飛び出すのを妨げるでしょう.私はこれに1週間以上取り組んできました.

class CensusDetail < ActiveRecord::Base  
  belongs_to  :apartment  
  belongs_to  :resident  
end  

class Apartment < ActiveRecord::Base  
  belongs_to :apartment_type  
  has_many  :census_details  
  has_many  :residents, :through => :census_details  
end  

class ApartmentType < ActiveRecord::Base  
  has_many :apartments  
end  

class Resident < ActiveRecord::Base  
  has_many :census_details  
  has_many :apartments, :through => :census_details  
end  

apartment.rent_ready       = boolean value if apartment is ready  
apartment_type.occupany    = the number of allowed occupants in an apartment  
census_detail.status       = either "past", "present", or "new"  
census_detail.moveout_date = date time resident is scheduled to move out 

次のことを行うクエリを作成する必要があります。

- if the apartment is rent ready then do the following:  
- pull a list from census_details of all residents set as "current" for each apartment  
  -if the # of residents is less than the value of apartment_type.occupancy for this  
    apartment, then list it as available  
  -if the # of residents is = to the value of apartment_type.occupancy then  
    -does any resident have a scheduled move out date  
      -if not, do not list the apartment  
      -if yes, then list apartment  

ヘルプや提案をお寄せいただきありがとうございます。