Getting entity id without query

cocorossello · **Joined:** Wed Apr 23, 2008 8:03 am **Posts:** 2

Hi,

I guess it might be a simple question, but i cant get a solution (if there is any).

Lets say i have this mapping:

class Document{
Integer id;
MyFileType file;
.....
}

class MyFileType{
Integer id;
Byte[] file;
}

Now somewhere in code i do a
Document document = session.load(Document.class, someId);

Is there any chance i can get document.file.id without actually doing another query or loading the whole file entity? Document.getFile().getId() loads the whole entity.

Anyway, the file.id is somewhere in the document object (the proxy)...

Thx in advance!

gonzao_diaz · **Joined:** Mon Nov 26, 2007 2:29 pm **Posts:** 443

Yes. Do an HQL query returning only that field, document.file.id, and retrieve it as a string with query.uniqueResult.

cocorossello · **Joined:** Wed Apr 23, 2008 8:03 am **Posts:** 2

I got it.

You can do:

session.getIdentifier(document.getFile());

and you get the identifier without an extra query.

gonzao_diaz · **Joined:** Mon Nov 26, 2007 2:29 pm **Posts:** 443

no, I mean an HQL query

Code:

  Query query=session.createQuery("select f.id from document.file f where document.id=xx");

  String fileId=(String)query.uniqueResult();