Navigating within an object in a Restriction

gogofe · **Joined:** Tue Aug 26, 2008 4:24 pm **Posts:** 29

Hy, If I am using the next code:
Suppose I have two tables:
person id(PK), name, cocheId(FK to cars table)
car: id(PK), name, colour, model(FK to carModel table)
carModel: id(PK), fabricationYear, etc...

Suppose the names of the columns of a database and the names of the properties in the three classes of hibernate are the same so:

If I want to know a person who has a car which fabricationYear is 1975 , I would to apply the next restriction to an object Person

-
- Restrictions.eq("cocheId.model.fabricationYear",1975 ));

Right?

Thanks

nordborg · **Posted:** Wed Jan 21, 2009 2:16 pm

No, that will not work. Criteria queries has no "implicit" joins as in HQL. You'll need to use either Criteria.createAlias() or Criteria.createCritera() to navigate associations. There are some example in the API doc (http://www.hibernate.org/hib_docs/v3/ap ... teria.html) and the reference documentation (http://www.hibernate.org/hib_docs/v3/re ... tions.html)

gogofe · **Joined:** Tue Aug 26, 2008 4:24 pm **Posts:** 29

Ok so just giving an alias to the object , I can navigate inside it but I dont understand what makes to give an alias to an object to be able to navigate inside it.

In my example should I do something like:

createAlias("cocheId.model", "model");
Restrictions.eq("model.fabricationYear",1975 ));

Thanks

mmerder · **Posted:** Thu Jan 22, 2009 4:56 am

Is your association really called "cocheId" and not "coche"? Remember that in order to use criteria you must have associations at class level, like:

Code:

public class Person {
  private Car coche;
  ...
}

your criteria could then look like:

Code:

session.createCriteria(Person.class).createCriteria("coche", "c").createAlias("c.model", "model").add(Restrictions.eq("model.fabricationYear",1975 ))