How to eager load a nested polymorphic association

Question

I'm trying to eager load a nested polymorphic association. I can't seem to find a solution.

Here is my model setup:

class Post
  has_many :comments
end

class Comment
  belongs_to :ownable, polymorphic: true
end

class User
  has_many :comments, as: :ownable
end

And here is what I'm trying to do:

Post.includes(comments: :ownable).to_a

But it's throwing this error:

ActiveRecord::EagerLoadPolymorphicError - Can not eagerly load the polymorphic association :ownable

How can I do eager load this nested polymorphic association?

Answer 1

First of all your post has_many comments should also be set :as => ownable

    class Post
      has_many :comments, as: :ownable
    end

Be even after changing this, you'll still get the same error since rails cannot find a table ownable.

There is a work around posted here Eager load polymorphic