Eager Load Depending on Type of Association in Ruby on Rails

Question

I have a polymorphic association (belongs_to :resource, polymorphic: true) where resource can be a variety of different models. To simplify the questio

Answer 1

You can break out your polymorphic association into individual associations. I have followed this and been extremely pleased at how it has simplified my applications.

class Issue
  belongs_to :order
  belongs_to :customer

  # You should validate that one and only one of order and customer is present.

  def resource
    order || customer
  end
end

Issue.preload(order: :address, customer: :location)

I have actually written a gem which wraps up this pattern so that the syntax becomes

class Issue
  has_owner :order, :customer, as: :resource
end

and sets up the associations and validations appropriately. Unfortunately that implementation is not open or public. However, it is not difficult to do yourself.