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Query by example does not read not null object

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Deepthought

Post subject: Query by example does not read not null object

Posted: Tue Mar 07, 2006 1:37 pm

Newbie

Joined: Thu Oct 13, 2005 11:43 am
Posts: 11

Hi,

when using the QBE interface I got a problem with the following code from my ImportFileHome.findOneByExample method:

Code:

 List results = HibernateUtil.getCurrentSession().createCriteria(ImportFile.class).add(Example.create(instance)).list();

The instance object is a new ImportFile object which has the facility set to "fac" and the master to a valid master instance from the database.
See the "Code between ..." section for more details.

The Problem:
The generated query (see "The generated SQL") does not contain anything from the master instance and I have no idea why. Please have a look. As a result of the generated query all ImportFiles from the DB are returned.

Hibernate version: 3.1

Mapping documents:

Code:

<hibernate-mapping>
   <class name="data.ImportFile" table="import_file" schema="public">
      <id name="id" type="short">
         <column name="id" not-null="true" />
         <generator class="sequence">
            <param name="sequence">import_file_id_seq</param>
         </generator>
      </id>
      <many-to-one name="master" class="data.Master" foreign-key="fk_master_file">
         <column name="master_id" not-null="true" unique-key="uk_import_file" />
      </many-to-one>
      <property name="facility" type="string" >
         <column name="facility" length="10" not-null="true" unique-key="uk_import_file" />
      </property>
      <property name="lastDayFileName" type="string">
         <column name="last_day_file_name" length="50" not-null="true" />
      </property>
   </class>
</hibernate-mapping>

Code between sessionFactory.openSession() and session.close():

Code:

        Master master = MasterHome.findById(new Short(1));
        ImportFile importFile = new ImportFile();
        importFile.setFacility("fac");
        importFile.setMaster(master);
        importFile = ImportFileHome.findOneByExample(importFile);
        importFile.setLastDayFileName("FileName");
        HibernateUtil.getCurrentSession().save(importFile);

Name and version of the database you are using:
PostgreSQL 8.0.4

The generated SQL (show_sql=true):

Code:

Hibernate: /* criteria query */ select this_.id as id9_0_, this_.master_id as master2_9_0_, this_.facility as facility9_0_, this_.last_day_file_name as last4_9_0_ from public.import_file this_ where (this_.facility=?)

The "where" clause should contain the id of the master instance or not? I would expect something like "where (this_.facility=? and this_master_id = ?)".

When I use

Code:

String masterId = "master_id =" + instance.getMaster().getId().shortValue();
String facility = "facility = '" + instance.getFacility() + "'";

List results = HibernateUtil.getCurrentSession().createCriteria(ImportFile.class).add(Expression.sql(masterId)).add(Expression.sql(facility)).list();

it works fine!

Any help will be appreciated.

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simonwillnauer

Post subject: Re: Query by example does not read not null object

Posted: Tue Mar 07, 2006 4:58 pm

Regular

Joined: Tue Mar 07, 2006 11:18 am
Posts: 54
Location: Berlin

You can setup ExampleQuerys even upon associated objects.
Try this:

Code:

Session session = HibernateUtil.getCurrentSession();
Criteria criteria = session.createCriteria(ImportFile.class);
criteria.add(Example.create(instance));
criteria.add(createCriteria("master")
         .add( Example.create(instance.getMaster()) );
List retVal = criteria.list();

simon

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Deepthought

Post subject: Re: Query by example does not read not null object

Posted: Wed Mar 08, 2006 3:46 am

Newbie

Joined: Thu Oct 13, 2005 11:43 am
Posts: 11

Simon,
thanks for your hint but I couldn't get it to work.

[quote="simonwillnauer"]You can setup ExampleQuerys even upon associated objects.
Try this:

Code:

Session session = HibernateUtil.getCurrentSession();
Criteria criteria = session.createCriteria(ImportFile.class);
criteria.add(Example.create(instance));
criteria.add(createCriteria("master")
         .add( Example.create(instance.getMaster()) );
List retVal = criteria.list();

There is no method "createCriteria("master")". I guess you meant session.createCriteria(Master.class).add( ..."?

The problem is also that the method criteria.add() only takes a Criterion and not a Criteria as argument. Could you explain further please?

Until now I was using the generated DAO classes from hibernate.
In my example the method ImportFile.findbyExample() did not work (using only the example instance and having no knowledge about any associated objects).

So I would like to know if this is a general problem and I can never do something like

Code:

List results = HibernateUtil.getCurrentSession().createCriteria(ImportFile.class).add(Example.create(instance)).list();

... to get the right query generated (including all associated objects) or if there is a problem with my mappings or code accessing ImportFile.findbyExample().

Chris

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simonwillnauer

Post subject: Re: Query by example does not read not null object

Posted: Wed Mar 08, 2006 8:08 am

Regular

Joined: Tue Mar 07, 2006 11:18 am
Posts: 54
Location: Berlin

:) i posted the wrong code.... (I'm getting code-blind after 10h work) sorry about that.

Code:

List results = session.createCriteria(ImportFile.class)
     .add( Example.create(instance))
     .createCriteria("master")
      .add( Example.create( instance.getMaster() ) )
     .list();

that should do the job...

simon

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