Hibernate noob - retrieve partial object

Question

Greetings!

I have the following class and at times need to retrieve only title and subTitle elements:

public class Article implements Serializable {

    private static final long serialVersionUID;
    private int id;
    private String title;
    private String subTitle;
    private String body;
    ....
}

What's the best way to facilitate this? I thought about making title and subTitle stand alone objects but I honestly don't know what I'm doing yet.

I have the luxury of changing the entire composition of Article, but asking first is the most sensible thing for me at the moment.

Thanks in advance.

Is there a specific reason you want to do this? Why does it matter if Hibernate loads the extra fields? You're not required to use them. — brainimus, Jan 27 '11 at 13:22
... in all honesty, it seems very counter intuitive to be loading everything when I need only a few bits. In practical terms I could load the whole thing, but then I'm thinking performance and scale, at least in theory. — vector, Jan 27 '11 at 13:28
Not returning those fields is not going to affect performance. Worry about the functionality of your application, not making a 0.001 second query run 0.000000000001 second faster. — Phill, Jan 27 '11 at 14:00
... Phill, if you post your comment as an answer, I'll at least vote it up, or accept it. — vector, Jan 28 '11 at 15:59

score 1 · Accepted Answer · answered Jan 27 '11 at 13:41

1

You can annotate every simple property with LAZY -> just like this @Basic(fetch = FetchType.LAZY)

So, it will be loaded only if you need

answered Jan 27 '11 at 13:41

Plínio Pantaleão

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That's the Java version, although the concept still applies (`lazy="true"` in the mappings) – Diego Mijelshon Jan 27 '11 at 14:34

score 1 · Answer 2 · edited May 23 '17 at 12:22

1

Provided this is for displaying purpose, you could also rely on a ResultTransformer.

See this SO answer which deals with similar problem and limits the retrieved properties.

edited May 23 '17 at 12:22

Community

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answered Jan 27 '11 at 13:47

nulltoken

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score 1 · Answer 3 · answered Jan 27 '11 at 16:41

I think you can solve this by creating a specific class to hold the information you want, then you import it in your mapping. See 5.1.19.import in the manual. I believe you can use the imported class in your HQL, like this:

"select new Titles(a.title, a.subTitle) from Article a where a.id = :id"

Here's a blog post I found on this subject: http://gustavoringel.blogspot.com/2009/02/creating-dto-in-nhibernate-hql-using.html.

Good luck!

Hibernate noob - retrieve partial object

3 Answers3