ActiveRecord::Relation#empty? fails for grouped relations, as OrderedHash is missing #zero?

Today i came over this error too...
Using Rails 3.0.3, Ruby 1.8.7 Enterprise Edition

# Showing /var/www/truhlari/app/views/articles/_detail.html.haml where line #103 raised:
# undefined method `zero?' for #<OrderedHash {"570"=>1, "683"=>1, "551"=>1, "553"=>1}>

# causing line in view:
if article.more_articles.active.published.any?

# model:
def more_articles
 ids = self.categories.collect(&:id).compact
 return self.class.scoped.joins("join e3_assocs on `item2_id` = `e3_models`.`id`").where("`item1_id` IN (#{ids.compact.join(',')})").group('`e3_models`.`id`')
end

Calling .empty? instead of .any? does the same...

It seems to be solved for my case by using .select("DISTINCT()...")

But it would not be so easy-solvable for different code cases .. :/

This is quite annoying. But since most results are iterated over anyway, you could just use .to_a.empty? or .all.empty?:
(of course this is only sensible when limit() is involved)

@articles = Article.published.group("publisher_id").limit(10).to_a.empty?

Not to speak of other problems with using count() on your ActiveRecord::Relation when limit() or offset() is involved.
You just cannot use a count/size on a scope and rely on the result.
for example see: #4882 ActiveRelation bug; size() returning incorrect value with limit().

Same issue for me with the following scope:

  scope :quantity_for_bs, lambda {|bs_id|{
      :joins => :shipment,
      :select =>  '*, SUM (quantity) as total_quantity',
      :group => :item_variant_id,
      :conditions => {:shipments => {:dest_site_id => bs_id}}
  }}

Then if I do

  shi  = ShippingItem.transiting.quantity_for_bs(@business_site.id)
  shi.empty? # <- raises undefined method `zero?' for {}:ActiveSupport::OrderedHash

Interestingly, if I do shi.inspect in between the statements, then .empty? resolves correctly...

(from [015192560b7e81639430d7e46c410bf6a3cd9223]) Fixed a bug when empty? was called on a grouped Relation that wasn't loaded

[#5829 ActiveRecord::Relation#empty? fails for grouped relations, as OrderedHash is ... state:resolved]

Signed-off-by: Andrew White andyw@pixeltrix.co.uk
https://github.com/rails/rails/commit/015192560b7e81639430d7e46c410...