How to extend JPA entity NamedQueries?

[Ralf Butler]

Hi there,

How do I extend a JPA entity in regard to its NamedQueries. Following doesn't work:

import javax.persistence.Entity;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;

@Entity
@NamedQueries({@NamedQuery(name = "_Nodetype.findByNodeDataType", query = "SELECT n FROM _Nodetype n INNER JOIN n.nodedatatype nd WHERE nd.shortname= :shortname")})

public class _Nodetype extends entityClasses.auto.Nodetype{

}

I then invoke the whole thing via:

Query selectQuery = ENTITY_MANAGER.createNamedQuery("_Nodetype.findByNodeDataType");
selectQuery.setParameter("shortname", "CS");
Nodetype nodetype = (Nodetype) selectQuery.getSingleResult();

I receive the error message that singleResult is empty.

Help is much appreciated.
Thanks

[Mark Spritzler]

OK. These two are just nitpicks and you don't have to change it.

1) I put my Named queries above the @Entity because Named Queries, while you have them in a class are not scoped to the class but to the SessionFactory.
2) What is with all those front underscores. "_". This is Java we don't use underscores in variable names. ;)

So do you have show_sql on so that you can see the query that gets run? Then check to see if the query itself actually returns records from the database. The error that shows is saying that the query is running except that the result set has no records in it.

Mark