客房預訂系統查詢

Question

我有以下的關聯

User: 
    has_many :reservations 
    has_many :rooms, through: :reservations 
Room: 
    has_many :reservations 
    has_many :users, through: :reservations 
Reservation: 
    belongs_to :room 
    belongs_to :user 

在我的預約模式，我有如下領域

CHECKIN_DATE，CHECKOUT_DATE

我想找出所有的客房，在給定時間內尚未保留。

我寫下面的查詢，但它不工作。請建議更正或更好的方法。

Room.joins('LEFT JOIN reservations ON reservations.room_id = rooms.id').where.not(
     'reservations.checkin_at < :requested_end_date AND 
     reservations.checkout_at > :requested_start_date', 
     requested_start_date: date_begin, 
     requested_end_date: date_end 
    )  

Answer 1

解決方案

class Room < ActiveRecord::Base 

    has_many :reservations 
    has_many :users, through: :reservations 

    def self.find_unreserved date_begin, date_end, category 
    reserved_room_ids = Reservation.on(date_begin, date_end).pluck('DISTINCT room_id') 
    if reserved_room_ids.empty? 
     where(category: category) 
    else 
     where('id NOT IN ?', reserved_room_ids).where(category: category) 
    end 
    end 

end 

class Reservation < ActiveRecord::Base 
    belongs_to :room 
    belongs_to :user 


    scope :on, -> (checkin_date, checkout_date) {where('checkin_at > ? AND checkout_at < ?', checkin_date, checkout_date) } 
end 

Answer 2

也許......

Room.joins('left join reservations on reservations.room_id = rooms.id') 
      .where('reservations.checkin_at > ? AND reservations.checkout_at < ?', date_begin, date_end) 
      .where('reservations.room_id IS NULL')