ActiveRecord Relation size strange behavior

0
votes

I have encountered some strange behavior of ActiveRecord Relation recently. Suppose, I have a Stat model with the following properies:

  • clicks
  • views
  • created_at
  • and others

Further suppose I have the following scope:

scope :aggregated, select('SUM(clicks) as clicks, SUM(views) as views).group('DATE(created_at)')

As a result I expect to get an array of Stat object with info aggregated by day, and so it is. But now consider this:

# in one place
a = Stat.aggregated    
#in other place
if a.size > 0
  'do stuff'
else
  'do other stuff'
end

And it works fine if a relation is loaded, but when a is not loaded it fails with method undefined error. It turns out that when relation is not loaded size calls count on that relation, which essentially changes the query, returns a hash, and brakes the code.

Is it an implied behavior?

For me it is kind of counter-intuitive to change method semantics depending on whether relation was loaded or not.

1
ruby-on-railsrubyactiverecord

1 Answers

0
votes

That's how ActiveRecord Relation works. You can convert it into an array and do a size on it. 

a = Stat.aggregated.to_a  
#in other place
if a.size > 0
  'do stuff'
else
  'do other stuff'
end