Question

Here is my model:

class User < ActiveRecord::Base
  has_many :activities
  has_many :requests

class Activity < ActiveRecord::Base
  belongs_to :user
  belongs_to :object, :polymorphic => true

I want to get all the users activities and display them

Activity.where(:user_id => current_user.id).include(:object)

the problem is that I can’t eager load the object model because it’s polymorphic
How do I overcome this problem?

Answer 1

Eager loading is supported with polymorphic associations. You will need to do something along the following lines:

Activity.find(:all, :include => :objectable, :conditions => {:user_id => current_user.id})

Although you need to make sure that you have defined the polymorphic relationship correctly on the associated models.

For further help refer to:
http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#label-Eager+loading+of+associations

The polymorphic part is at the end of “Eager loading of Associations” section.