Question

I have a rails app with three models: Account, Package and Delivery. I’m using AR::Relation scopes on Delivery to find recent deliveries and returns. The Account model also needs to find accounts with recent deliveries. Can I use the same Delivery scopes in Account via joins? Right now I’m using code like this (note the duplication in Account.with_recent_returns and 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

I believe something like this will work

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

or perhaps you’ll need to use scoped

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

should get you started.