EagerLoadPolymorphicError being thrown whenever conditions used

[ghost]

I am running will_paginate 3.0.pre2 on rails 3.0.7, and there seems to be some type of strange bug where a EagerLoadPolymorphicError is being raised whenever almost any conditions are used.

My 2 relevant models are very simple:
class Book
boolean public
belongs_to :author, :polymorphic => true
end
class Individual
has_many :books, :as => :author
end
class Group
has_many :books, :as => :author
end

This query will raise the exception:
Book.where(:public => true).includes(:author).paginate(:page => @page, :per_page => page_size, :order => "id DESC")

I have tried modifying the condition in a number of ways, and the only way that makes it not throw an exception is if the condition is on the id column, oddly enough.

[mislav]

Looks like an Active Record bug. Can you try again with latest will_paginate from master branch and Rails 3.0.9? Thanks

[ghost]

I just tried on Rails 3.0.9 with will_paginate 3.0.0 and the bug still behaves the same.

Book.where(:public => true).includes(:author).limit(10).order(:id) works correctly.
Book.where(:public => true).includes(:author).paginate(:page => 1, :per_page => 10, :order => :id) fails
Book.where(:id => [1,2,3]).includes(:author).paginate(:page => 1, :per_page => 10, :order => :id) works correctly.

[mislav]

Thanks for all the info. I will try to work around the bug. The current test suite doesn't have polymorphic associations, so this went undetected.