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Criteria Query- double selects, overwrites object graph

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Aleric

Post subject: Criteria Query- double selects, overwrites object graph

Posted: Tue Jun 29, 2004 3:32 pm

Newbie

Joined: Wed Jun 23, 2004 4:35 pm
Posts: 13

I have an object mapped like this;

Code:

    <class name="Recip"
...   
     >
      
        <cache usage="read-only" />

        <id
            name="id"
            column="rid"
            type="java.lang.Integer">
         
            <generator class="assigned"/>
        </id>

        <property
...  
       />

   <one-to-one
         name="serSet"
         class="SerSet"
         outer-join="false"/>
         
   <set name="dnaSet">
      <key column="rid"/>
      <one-to-many class="AntHist"/>
   </set>

    </class>

The following query works fine;

Code:

Criteria criteria = session.createCriteria(Recip.class)
                          .add(Expression.eq("id", new Integer(123456)));
criteria.createCriteria("serSet")
            .add(Expression.eq("phenSeqNumber", new Integer(1)));

But if I add this;

Code:

criteria.createCriteria("dnaSet")
            .add(Expression.like("typMeth", "DNA"));

Then hibernate performs two selects instead of one. Worst of all, the sql from the first is correct and maps to the object graph correctly but the second select gets bad results and overwrites the object graph.

How do I get it to stop?

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Aleric

Post subject: Don't extend java.util.Set?

Posted: Tue Jun 29, 2004 5:56 pm

Newbie

Joined: Wed Jun 23, 2004 4:35 pm
Posts: 13

One thing I left out that I now realize is critical;

The class I use for dnaSet is actually an extension of HashSet. Although the property is passed in as a Set, I transform the Set into a DnaSet before storage.

Since Hibernate replaces Collection objects with its own versions of Collections, the cache can no longer recognize a Collection it has already loaded. So it attempts to lazily initialize the collection but now is wrong-footed.

The solution seems to be to not extend HashSet and place the needed functionality in another object. Which would seem to be a better plan anyway since the goal was to "flatten out" the data in the first place.

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