使用ActiveRecord ::跨模型的关系

Question

我有一个rails应用程序，有三种模型：帐户，包装和交付。我在交付上使用AR :: Relation范围来查找最近的交付和退货。帐户模型还需要查找近期交付的帐户。 我可以通过joins在帐户中使用相同的交付范围吗？现在，我用这样的代码（注意Account.with_recent_returns重复和Delivery.recent_returns）：

# Package(id: integer, ident: string) 

class Package < ActiveRecord::Base 
    has_many :deliveries, :dependent => :destroy 
end 

# Delivery(id: integer, account_id: integer, delivered_on: date, package_id: integer, returned_on: date)` 

class Delivery < ActiveRecord::Base 

    belongs_to :account 
    belongs_to :package 

    scope :current, where(:returned_on => nil) 

    scope :recent_deliveries, where('delivered_on >= ?', 2.weeks.ago) 

    scope :recent_returns, where('returned_on >= ?', 2.weeks.ago) 

    scope :returns, where('returned_on IS NOT NULL') 
end 

# => Account(id: integer, name: string) 

class Account < ActiveRecord::Base 

    has_many :deliveries, :dependent => :destroy 

    def self.with_current_deliveries 
    joins(:deliveries).where(:deliveries => { :returned_on => nil }).includes(:deliveries) 
    end 


    def self.with_recent_returns 
    joins(:deliveries).where('deliveries.returned_on >= ?', 2.weeks.ago).includes(:deliveries) 
    end 
end 

Answer 1

我相信这样的事情会工作

scope :recent_deliveries, joins(:deliveries).merge(Delivery.recent)

或许你需要使用范围的

scope :recent_deliveries, scoped.joins(:deliveries).merge(Delivery.recent)

应该让你开始。