java - JPA 2.0: TYPE expression exception -

i have inheritance structure classes, let's parent (as root class) , child subclass.

so jpa 2.0 no can select parent class using

select p parent p type(p) = parent 

this should return entries of parent , not entries of child.

but eclipselink 2.1.1 , mysql on glassfish v3, following error:

"invalid type expression on [my.domain.parent].  class   not have descriptor, or descriptor not use   inheritance or uses classexctractor inheritance".  

additionally, define no orm-mapping hand. done automatically on deployment, think.

is there have add parent /child class (an annotation i.e.) declare inheritance structure? (but think shouldn't necessary, because inheritance declared java, it?)

edit:
1 important aspect i've didn't mentioned i'm using inheritance method "table_per_class".

forget said before. work single_table strategy:

@entity @table(name="person") @inheritance(strategy=inheritancetype.single_table) @discriminatorcolumn(name="gender", discriminatortype=discriminatortype.string, length=6) public abstract class person implements serializable {     private static final long serialversionuid = 1l;      @id     @sequencegenerator(name="person_personid_generator", sequencename="person_id_seq")     @generatedvalue(strategy=generationtype.sequence, generator="person_personid_generator")     @column(name="person_id", updatable=false, unique=true, nullable=false, precision=22)     private long personid;      @column(nullable=false, length=32)     private string surname;      @column(name="given_name", nullable=false, length=32)     private string givenname;      // ... }   @entity @discriminatorvalue("female") public class daughter extends person implements serializable {      @column(name="number_of_dolls", precision=22)     private int numberofdolls;      // ... }   @entity @discriminatorvalue("male") public class son extends person implements serializable {      @column(name="number_of_toy_cars", precision=22)     private integer numberoftoycars;      // ... }   // junit test method public void testinheritance() {     entitymanager em = createnewentitymanagerinstance();      entitytransaction tx = em.gettransaction();     tx.begin();     daughter d = new daughter();     d.setgivenname("sue");     d.setsurname("smith");     d.setnumberofdolls(5);     em.persist(d);     son s = new son();     s.setgivenname("joe");     s.setsurname("smith");     s.setnumberoftoycars(8);     em.persist(s);     tx.commit();      query q;     list<?> personlist;     person p;      q = em.createquery("select p person p type(p) = daughter");     personlist = q.getresultlist();     assertequals(1, personlist.size());     p = (person)personlist.get(0);     system.out.println(         "this daughter is: " + p.getgivenname() + " " + p.getsurname());     q = em.createquery("select p person p type(p) = son");     personlist = q.getresultlist();     assertequals(1, personlist.size());     p = (person)personlist.get(0);     system.out.println(         "this son is: " + p.getgivenname() + " " + p.getsurname());     q = em.createquery("select p person p");     personlist = q.getresultlist();     assertequals(2, personlist.size());     (object o : personlist) {         asserttrue(o instanceof person);         p = (person)o;         system.out.println(             "this person is: " + p.getgivenname() + " " + p.getsurname());     }     em.close(); } 

the database (i'm using oracle) ddl looks this:

create table "dev"."person"   (   "person_id" number not null enable,    "given_name" varchar2(32 byte) not null enable,    "surname" varchar2(32 byte) not null enable,    "gender" varchar2(6 byte) not null enable,    "number_of_dolls" number,    "number_of_toy_cars" number,     constraint "person_pk" primary key ("person_id")   );   

now said you're trying use table_per_class strategy. can't there, since the jpa 2.0 spec says vendors not required support it. implementation may not support via jpa interfaces.