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Type:
Task
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Resolution: Done
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Affects Version/s: None
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Component/s: None
Unless I'm mistaken,
class A include Mongoid::Document end class B < A belongs_to :c end class C include Mongoid::Document has_one :b end C.create C.create B.create(:c => C.last) Mongoid.identity_map_enabled = true C.all.includes(:b).collect(&:b)
should only result in two queries, namely
QUERY database=mongoid_test collection=cs selector={} flags=[] limit=0 skip=0 fields=nil (0.0006ms)
QUERY database=mongoid_test collection=as selector={"c_id"=>{"$in"=>["4ff487828ef895c465000001", "4ff487878ef895c465000003"]}, "_type"=>{"$in"=>["B"]}} flags=[] limit=0 skip=0 fields=nil (0.0005ms)
While those two are indeed performed, a third one also is:
QUERY database=mongoid_test collection=as selector={"c_id"=>"4ff487828ef895c465000001", "_type"=>{"$in"=>["B"]}} flags=[] limit=-1 skip=0 fields=nil (0.0005ms)
So it looks like eager loading works but the identity map doesn't know how to properly handle subclasses and thus "forgets" that eager loading has taken place. Is this by design or might it be a bug?
I am seeing this behaviour with mongoid master on Ruby 1.9.3p194.