Rails的：范围有过滤器嵌套属性

Question

我的模型有如下关系：

Building有很多Room S作很多Bed S作许多Accommodation S，

，我想呈现的所有Building秒，但在日期范围内创建了Accommodation。从其他答案我明白，我需要为Building模型创建范围，但我无法理解如何过滤此范围内的嵌套属性。

编辑：

可以说我有Building 1，2和3。每个Building都有它自己的Room S的有Bed S的有Accommodation秒。可以说只有Building 1有一个Accommodation在范围内。因此，返回的数据必须是：

Building 1 
    ... 
    Room n 
     ... 
     Bed n 
     Accommodation that is in range 
     Bed n+1 
     ... 
    ... 
Building 2 (accommodation arrays in beds are empty since there are no accommodations that are in range) 
    ... 
Building 3 (accommodation arrays is beds are empty since there are no accommodations that are in range) 
    ... 

Answer 1

class Building 
    scope :accomodations_for_dates, lambda { |start_date, end_date| 
    joins(rooms: [beds: :accomodations]).where("accomodations.created_at >= #{start_date} AND accomodations.end_date <= #{end_date}") 
    } 
end 

在PostgreSQL和MySQL数据库，你可以使用BETWEEN：

"accomodations.created_at BETWEEN #{start_date} AND #{end_date}" 

要返回所有的建筑但过滤住宿您想使用包括：

includes(rooms: [beds: :accomodations]).where(accomodations: { created_at: start_date..end_date }) 

Answer 2

为了避免必须在您的模式下编写过多的嵌套连接查询setup indirect relations L：

class Building 
    has_many :rooms 
    has_many :beds, though: :rooms 
    has_many :accomodations, though: :beds 
end 

class Room 
    belongs_to :building 
    has_many :beds 
    has_many :accomodations, though: :beds 
end 

class Bed 
    belongs_to :room 
    has_many :accomodations 
    has_one :building, through: :room 
end 

class Accommodation 
    belongs_to :bed 
    has_one :room, through: :bed 
    has_one :building, through: :room 
end 

这将让你直接查询building.accomodations和ActiveRecord的将加入中间表为您服务。

然后，只需使用Range查询时：

Building.includes(:accommodations) 
     .where(accommodations: { created_at: start_time..end_time }) 

这将建设与大多数数据库驱动程序一个WHERE 'accommodations.created_at' BETWEEN ...。

难题的另一个关键在于你没有过滤嵌套属性。相反，上面发生的是您正在使用join and setting conditions on the joined table。