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How use criteria correctly?

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lefay

Post subject: How use criteria correctly?

Posted: Wed Jan 28, 2004 5:27 am

Newbie

Joined: Tue Jan 27, 2004 7:48 am
Posts: 1

Good time of day!

I have follow question.

I have city, building and buildingOwner persistance objects in my application and I wish to select all buildings with city where building.buildingOwner.name = "BuildingOwnerName" and sorted by city.name.

city have one-to-many relation to building and
buildingOwner have one-to-many relation to building

When I using HQL:

select distinct building, city
from
city in class com.myapp.City,
building in city.buildings.elements,
where
building.buildingOwner.name = "BuildingOwnerName"
order by
city.name

How can do it with using Criteria?

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drj

Post subject:

Posted: Wed Jan 28, 2004 8:27 am

Expert

Joined: Fri Nov 07, 2003 4:24 am
Posts: 315
Location: Cape Town, South Africa

I'm not sure how to return multiple objects in a criteria query (or even if it is possible), but you could try something like:

Code:

Criteria crit = session.createCriteria(City.class)
    .createCriteria("buildings")
    .add(Expression.eq("buildingOwner.name", name)

Code:

Criteria crit = session.createCriteria(City.class)
    .createCriteria("buildings")
    .createCriteria("buildingOwner)
    .add(Expression.eq("name", name)

I haven't tried multiple join paths in an Expression either (first example) but it may work....

This should return a list of Cities objects and you can throw out duplicates/navigate the tree.

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l.masini

Post subject:

Posted: Wed Jan 28, 2004 10:28 am

Beginner

Joined: Tue Nov 11, 2003 4:49 am
Posts: 47
Location: Florence, Italy

This is a piece of code I use that do what you asked.
Ciao.

Code:

   
   public List ricercaMalattia(String nome, String cognome, Date inizio, Date fine)
   {
      try
      {
         Criteria ricercaMalattie = HibernateSession.getSession().createCriteria(MalattiaImpl.class);
         
         if (inizio != null)
         {
            ricercaMalattie.add(Expression.gt("inizio", inizio));
         }

         if (fine != null)
         {
            ricercaMalattie.add(Expression.lt("fine", fine));
         }

         ricercaMalattie = ricercaMalattie.createCriteria("dipendente");
         
         if (StringUtils.isNotBlank(nome))
         {
            ricercaMalattie = ricercaMalattie.add(Expression.like("nomeProprio", nome+"%"));
         }

         if (StringUtils.isNotBlank(cognome))
         {
            ricercaMalattie = ricercaMalattie.add(Expression.like("cognome", cognome+"%"));
         }
         
         return ricercaMalattie.list();
      }
      catch (HibernateException e)
      {
         return Collections.EMPTY_LIST;
      }
   }

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drj

Post subject:

Posted: Thu Jan 29, 2004 12:55 am

Expert

Joined: Fri Nov 07, 2003 4:24 am
Posts: 315
Location: Cape Town, South Africa

Instead of

Code:

ricercaMalattie = ricercaMalattie.add(Expression.like("nomeProprio", nome+"%"));

You can use:

Code:

ricercaMalattie = ricercaMalattie.add(Expression.like("nomeProprio", nome, MatchMode.START));

Also - beware of not propagating or logging your exceptions.
I would (at least):

Code:

 catch (HibernateException e)
      {
         log.warn(e.getMessage()); // log being an org.apache.commons.logging.Log class
         return Collections.EMPTY_LIST;
      }
   } 

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l.masini

Post subject:

Posted: Thu Jan 29, 2004 4:15 am

Beginner

Joined: Tue Nov 11, 2003 4:49 am
Posts: 47
Location: Florence, Italy

Thank you for your advice about criteria, It's yet in my code ;-)
The missing log was a fault of that piece of code only.
Ciao.

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