[JPA] SELECT NEW inside SELECT NEW in Named Query

Question

Suppose i have two JPA entities Master and Detail as follows:
@Entity
public class Master implements Serializable{
    private static final long serialVersionUID = 1L;
    private long id;
    private String masterField1;
    private String masterField2;
    private String masterField3;
     private String masterField4;
    private String masterField5;   
    //A lot of other fields till masterFieldn...
    private String masterFieldn;
    private List<Detail> detailList;
    //getters and setters here...
    @OneToMany(mappedBy = "master", cascade = { CascadeType.ALL }, fetch=FetchType.EAGER)
    @OrderBy("detailField1 DESC")
    public List<Detail> getDetailList() {
        return detailList;
@Entity
public class Detail implements Serializable{
    private static final long serialVersionUID = 1L;
    private long id;
    private String detailField1;
    private String detailField2;
    private String detailField3;
     private String detailField4;
    private String detailField5;   
    //A lot of other fields till detailFieldn...
    private String detailFieldn;
    private Master master;
    //getters and setters here...
    @ManyToOne
    @JoinColumn(name="MASTER_ID", referencedColumnName="ID")    public Master getMaster() {
        return master;
    }Both Master and Detail entities have a lot of fields, but i only need a subset of those fields when these entities are queried. So, i have two helper classes which i use in named queries in Master JPA entity :
@NamedQueries({
        @NamedQuery(name = "Master.findMaster",
            query = "SELECT NEW MasterHelper(" +
                "t.masterField1, t.masterField2, t.masterField3, " +
                " SELECT NEW DetailHelper(" +
                "td.detailField1, td.detailField2, td.detailField3 FROM Detail td WHERE " +
                " td.master.id = t.id)) FROM Master t WHERE t.id = ?1")MasterHelper and DetailHelper have only the fields i want to query, getters and setters, and a constructor matching the SELECT NEW.. in @NamedQuery :
public class MasterHelper implements java.io.Serializable {
    private String field1;
    private String field2;
    private String field3;
    private <DetailHelper> detailList;
    //Constructor matching SELECT NEW
    public MasterHelper(String field1, String field2, String Field3, List detailList) {
       this.field1 = field1;
        this.field2 = field2;
        this.field3 = field3;
        this.detailList = detailList;
     //getters and setters
public class DetailHelper implements java.io.Serializable {
    private String field1;
    private String field2;
    private String field3;
    //Constructor matching SELECT NEW
    public DetailHelper(String field1, String field2, String Field3) {
       this.field1 = field1;
        this.field2 = field2;
        this.field3 = field3;
     //getters and setters
}So, basically when i query for a particular Master entity, what i want in return is a List of MasterHelper objects with just the fields i want; each MasterHelper object must include a list of MasterDetail objects, again with just the fields i want.
When the above named query is executed by Toplink Essentials against an Oracle database, i get the following exception regarding the "second" SELECT NEW:
EJBQLException
Exception Description: Syntax error parsing the query [SELECT NEW
...unexpected token [SELECT]
...How can i achieve what i want? Doesn't JPA allows SELECT NEW inside SELECT NEW in named queries?
Thanks in advance for any help.
Edited by: savas_karabuz on May 16, 2008 3:59 AM
Edited by: savas_karabuz on May 16, 2008 4:02 AM

Answer 1

Hello,
The build you are using is an older one, and there have been a few enhancements done for constructor expressions support (for instance
https://glassfish.dev.java.net/issues/show_bug.cgi?id=1421)
but an enhancement to allow constant values is still open: https://glassfish.dev.java.net/issues/show_bug.cgi?id=2452
Best Regards,
Chris