具有多态关联的多个内连接

Question

I have the following polymorphic association...

class Activity < ActiveRecord::Base
  belongs_to :owner, polymorphic: true
end

class User < ActiveRecord::Base
  has_many :activities, as: :owner
end

class Manager < ActiveRecord::Base
  has_many :activities, as: :owner
end    

I am trying to make a query whereby it only pulls out the activities where the owner (user or manager) has visible set to true .

I have figured out that if I want to do this for one of the owners, I can do this as follows...

Activity.joins("INNER JOIN users ON activities.owner_id = users.id").where(:activities => {:owner_type => 'User'}).where(:users => {:visible => true})

But I cannot figure out how to do it for both. Can anyone help?

Answer 1

This should work:

Activity.
  joins("LEFT JOIN users ON activities.owner_type = 'User' AND
                            activities.owner_id = users.id").
  joins("LEFT JOIN managers ON activities.owner_type = 'Manager' AND
                               activities.owner_id = managers.id").
  where("users.visible = ? OR managers.visible = ?", true, true)