ActiveModel::MissingAttributeError occurs after deploying and then goes away after a while

Question

I have a Rails 3.0.9 app that, once it is deployed, suffers from a bunch of ActiveModel::MissingAttributeErrors that crop up causing 500s. The errors occur fairly randomly,

Answer 1

I found an interesting take on this that resulted in the same error. In an attempt to reuse code we subclasses a presenters class with a presenters class that performed grouping to use in a graph view.

To simplify, it was something like:

class PostPresenter 
  def query
    Post.where(...stuff....).includes(:wombat)
  end
end

The the aggregator did something like the following to build a table of posts per day:

class AggregatePostPresenter < PostPresenter
  def group_query
    query.select('count(*) as cnt, date(created_at)').group('date(created_at)')
  end
end

A call to "group_query" results in an ActiveModel::MissingAttributeError since, I think, the attempt to "includes" Wombat fails because "wombat_id" wasn't in the attributes included in the "select".

This is probably not your answer, however, since it happens regardless of whether or not cache is enabled.