如何优化这种关联链？

I have an Event model with a many-to-many association with a Service model

我有一个与服务模型具有多对多关联的事件模型

A user can create an event and choose what services are tagged to that event.

用户可以创建事件并选择标记到该事件的服务。

A user can subscribe to a service, and when an event gets created the user should be notified if the user has subscribed to a service that was tagged in that event.

用户可以订阅服务,并且当创建事件时,如果用户订阅了在该事件中标记的服务,则应该通知用户。

In addition, the User model has a has_many association to an Email model.

此外,User模型与Email模型具有has_many关联。

I'd like to be able to get an array of all the email addresses so I can send a notification to the subscribers.

我希望能够获得所有电子邮件地址的数组,以便我可以向订阅者发送通知。

Here's what I have:

这就是我所拥有的:

class Event < ActiveRecord::Base

  has_many :event_services, :dependent => :destroy
  has_many :services, :through => :event_services

  def recipients
    recipients = services.each_with_object(arr = []) do |service|
      service.users.each do |user|
        user.emails.each do |email|
          arr << email.address
        end
      end
    end
  end
  recipients.uniq
end

This works, but its super ugly and not very efficient. How would I go about optimizing this?

这是有效的,但它超级丑陋,效率不高。我该如何优化这个?

Here's my Email model:

这是我的电子邮件模型:

class Email < ActiveRecord::Base
  attr_accessible :address, :user_id  
  belongs_to :user
end

1 个解决方案

#1

It would be more efficient with a single SQL request The following request, using multiple joins, should work:

使用单个SQL请求会更有效使用多个连接的以下请求应该有效:

def recipients
  Email.joins(:user => {:services => :event_services}).where(:event_services => {:event_id => self.id}).pluck(:address).uniq
end