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 Post subject: Fetching only one child
PostPosted: Tue Sep 18, 2007 9:49 am 
Newbie

Joined: Thu May 18, 2006 6:36 am
Posts: 11
Location: Bangalore
Hi,

I have a one-to-many mapping between two of my classes, what I want to archive is that only one of the child gets retrieved when the parent is retrieved.

How can i achieve this, I tried to set lazy="false" and batch-fetch-size as 1, at the same time changed the fetch strategy to Join, but this doesn't seem to be working.

Is there any other way I can achieve this.Can i write a query which can help me do this.I need only one of the child's to be displayed.

Thanks,
Rohit


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 Post subject:
PostPosted: Tue Sep 18, 2007 10:34 am 
Newbie

Joined: Wed Sep 12, 2007 1:58 pm
Posts: 12
Take a look at the org.hibernate.Query API, in particular the setFirstResult() and setMaxResults() methods.


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 Post subject:
PostPosted: Tue Sep 18, 2007 10:41 am 
Newbie

Joined: Thu May 18, 2006 6:36 am
Posts: 11
Location: Bangalore
Hi,

Thanks for the help, but this will return one or more records.

My requirement is that i want all the parent records but only one child for each parent.

Thanks,
Rohit


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 Post subject:
PostPosted: Tue Sep 18, 2007 10:58 am 
Newbie

Joined: Thu May 18, 2006 6:36 am
Posts: 11
Location: Bangalore
Hi,

Thanks for the help, but this will return one or more records.

My requirement is that i want all the parent records but only one child for each parent.

Thanks,
Rohit


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 Post subject:
PostPosted: Tue Sep 18, 2007 2:22 pm 
Beginner
Beginner

Joined: Fri Sep 08, 2006 7:29 am
Posts: 36
Try this....


1. setFirstResult(1)
2. setMaxResults(1)



Maybe this would work....


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 Post subject:
PostPosted: Tue Sep 18, 2007 2:31 pm 
Expert
Expert

Joined: Wed Apr 11, 2007 11:39 am
Posts: 734
Location: Montreal, QC
Do you need something like this?

Code:
select parent.children from Parent parent where parent.id = ?


and when you execute this set the maximum results to 1.


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 Post subject:
PostPosted: Tue Sep 18, 2007 3:57 pm 
Newbie

Joined: Mon Sep 17, 2007 1:28 pm
Posts: 6
this is pretty much crap but it would work


public void setChildren(List<Child> children) {
this.children = children.subList(0, 1);
}

obviously you'd want some bounds & null checks in there. More obviously you're probably looking for a solution at the db/hibernate level, just thought I'd throw this out there as a potential idea.

Don't forget to rate


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 Post subject: Re: Fetching only one child
PostPosted: Thu Dec 01, 2011 6:33 pm 
Newbie

Joined: Tue Apr 12, 2011 2:13 pm
Posts: 1
Is there something new?

I have a Parent with a List of Children. There can be thousands of children which were added over the applications life time.
Often I only want to load the newest child. (I use Criteria, Fluent NHibernate)

Is there meanwhile a meachnismen that (N)Hibernate do not load all children of the list in such a case?
I tried multiple thinks, but have no success.


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