populate a single object using multiple queries

jllydgnt · **Joined:** Wed May 03, 2006 4:34 pm **Posts:** 6

Can anyone recommend an approach for populating an object with multiple queries? An object that does not map directly to a table and cannot be completely populated with a single SQL statement. For example, if I have an object that contains the following.

studentId
studentName
numCourses
avgGrade
lowGrade
highGrade

Assume that there is no way to return all this in one query. How can I populate some of the properties with one query and then populate the rest with another query?

Hibernate version:3.1.3

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

It can't be done. However:

1) If all the tables in question are on the same server, then you can get them all back in one query (though it might be complicated): at the very worst, you can use a stored procedure to do the work.

2) You can use the <join> element to grab columns from other tables (see refdocs section 5.1.18).

3) You can use associations from the "main" object to other objects that are mapped separately. Then use delegation to add the other objects' methods to the main object. E.g.

Code:

public class MainClass ... {
  ...
  public int getValueA()
  {
    return getAssociatedObject().getValueA();
  }
  ...
}

jllydgnt · **Joined:** Wed May 03, 2006 4:34 pm **Posts:** 6

Yes, I think it would have to be done in a stored procedure to get it all at once. I want to avoid that, so I will be exploring the other options you recommended. Thanks.