How to prevent OpenJPA from updating immutable entities?

[egoosen]

I'm using OpenJPA with GWT, and therefore I'm copying my model object to a GWT friendly DTO, before passing it to the frontend (and visa versa when returning from the frontend).

When I check my debug output, I notice that there are update statements for entities that are supposed to be immutable (the database values don't change).
So I tried removing cascade = { CascadeType.PERSIST,CascadeType.MERGE }, to prevent the immutable entity from getting updated, but then I get this error:

org.apache.openjpa.persistence.InvalidStateException: Encountered unmanaged object in persistent field

Then I added this method to my DAO:
public TblScmpdt attachImmutableRelationships(TblScmpdt tblScmpdt){
                EntityManager em = getEntityManager();
                TblPdtcde tblPdtcde = em.find(TblPdtcde.class,tblScmpdt.getPdtcdeId());
                tblScmpdt.setTblPdtcde(tblPdtcde);
                return tblScmpdt;
        }

but I still get the InvalidStateException.

How do I stop OpenJPA from trying to merge/persist my immutable entities?

[egoosen]

I've found a solution to my problem...

tblScmpdt.setTblPdtcde(null); //immutable, don't merge
The foreign key is still set (tblScmpdt.pdtcdeId), so by setting the related entity to null, it prevents OpenJPA from trying to merge it.

[timfanelli]

I'd like to see the code for your TblPdtcde entity. I suspect that you
could simply set the "updateable=false" property on your column
attribute (or element, if xml) to achieve the same results without
having to impact your object model in this manner.

-Tim

On Wed, 2008-08-13 at 06:36 -0700, egoosen wrote:
> I've found a solution to my problem...
>
> tblScmpdt.setTblPdtcde(null); //immutable, don't merge
> The foreign key is still set (tblScmpdt.pdtcdeId), so by setting the related
> entity to null, it prevents OpenJPA from trying to merge it.

[egoosen]

Hi Tim,

I set the "updateable=false" property, but that didn't have any effect.

Here it is:
// Mapped Fields
        @TableGenerator(name="tblPdtcdeGenerator",schema="EBSTATUS",table="TBL_KEYGEN",pkColumnName="PRIMARY_KEY_COLUMN"
                ,valueColumnName="LAST_USED_ID",pkColumnValue="TBL_PDTCDE_ID",allocationSize=1)
                @Id
                @GeneratedValue(strategy=GenerationType.TABLE,generator="tblPdtcdeGenerator")
                @Column(name = "PDTCDE_ID",nullable=false)
                private Integer pdtcdeId;    

        @Basic
        @Column(name = "PDTTYP_CDE",nullable=false,updatable=false)
        private String pdttypCde;

        @Basic
        @Column(name = "PDT_CDE",nullable=false,updatable=false)
        private String pdtCde;

        @Version
        @Column(name = "VRS_NBR")
        private Integer vrsNbr;


// Mapped Relationships
        @OneToMany(mappedBy="tblPdtcde",fetch = FetchType.LAZY)
        private Collection<TblPdtbnfcde> tblPdtbnfcdes = new ArrayList<TblPdtbnfcde>();

        @OneToMany(mappedBy="tblPdtcde",fetch = FetchType.LAZY)
        private Collection<TblScmpdt> tblScmpdts = new ArrayList<TblScmpdt>();