NHibernate returning duplicate object in child collections when using Fetch
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UpTheCreek
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Published on 2011-01-17T14:32:50Z
Indexed on
2011/01/18
1:53 UTC
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nhibernate
When doing a query like this (using Nhibernate 2.1.2):
ICriteria criteria = session.CreateCriteria<MyRootType>()
.SetFetchMode("ChildCollection1", FetchMode.Eager)
.SetFetchMode("ChildCollection2", FetchMode.Eager)
.Add(Restrictions.IdEq(id));
I am getting multiple duplicate objects in some cartesian fashion. E.g. if ChildCollection1
has 3 elements, and ChildColection2
has 2 elements then I get results with each element in ChildColection1
one duplicated, and each element in ChildColection2
triplicated! This was a bit of a WTF moment for me...
So how to do this correctly?
- Is using SetFetchMode like this only supported when specifying one collection?
- Am I just using it wrong (I've seen some references to results transformers, but imagined this would be simplier).
- Is this something that's different in NH3?
Update:
As per Felice's suggestion, I tried using the DistinctRootEntity transformer, but this is still returning duplicates. Code:
ICriteria criteria = session.CreateCriteria<MyRootType>()
.SetFetchMode("ChildCollection1", FetchMode.Eager)
.SetFetchMode("ChildCollection2", FetchMode.Eager)
.Add(Restrictions.IdEq(id));
criteria.SetResultTransformer(Transformers.DistinctRootEntity);
return criteria.UniqueResult<MyRootType>();
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