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jpanamed-query

Why do I need to put @NamedQuery on Entity class?

I am currently learning about JPA NamedQueries and tried to use it in GuestServlet: 

Query getGuests =  em.createNamedQuery("myq");
@SuppressWarnings("unchecked")
List<Guest> guests = getGuests.getResultList();

It works when I put the @NamedQuery in Entity class:

@Entity
@NamedQuery(
    name="myq",
    query = "SELECT g FROM Guest g")
public class Guest {
  ...
}

But when I try to use it in Servlet as following:

@WebServlet({"/GuestServlet","/guest"})
@NamedQuery(
        name="myq",
        query = "SELECT g FROM Guest g")
public class GuestServlet extends HttpServlet {...}

I get the following error:

java.lang.IllegalArgumentException: No query defined for that name [myq]

Why am I forced to put @NamedQuery in Entity class while I use it in Servlet ?

Solution

  • The GuestServlet is not managed by your jpa provider. Hibernate (or whatever) simply isn't aware of the named query.