Re: Identity class and parent/children entity relationship

Paul Copeland Tue, 07 Apr 2009 12:34:42 -0700

Is there a workaround for 1.2.1?

I'm also hitting the reentrant flush exception with GenerationType.IDENTITY



On 3/30/2009 10:26 AM, Nemanja Joksovic wrote:

Thanks Fay,

I tried it before and it's working fine. But in production environment I need 
to using stable OpenJPA 1.2.x version (JPA 1.0 specification).

Regards,
Nemanja J.



The workaround is to use MappedById annotation (JPA 2.0 spec) in Openjpa trunk:

@Entity
public class Child implements Serializable {

        @EmbeddedId
        @Column(name = "id", unique = false, nullable = false)
        private ChildId childId;

        @MappedById("parent")
        @ManyToOne
        @JoinColumn(name = "parent_id", referencedColumnName = "id")
        private Parent parent;

...
}


@Embeddable
public class ChildId {
    public long id;
    public long parent;

...}



@Entity
public class Parent {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true, insertable = false, updatable = false, 
nullable = false)
        private long id;
        
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "parent")
        private List<Child> children = new ArrayList<Child>();
        
    private String name;

...}

For more detail, please see

org.apache.openjpa.persistence.enhance.identity.TestMappedById.testMappedById5

-Fay

--- On Mon, 3/30/09, Nemanja Joksovic <[email protected]> wrote:

From: Nemanja Joksovic <[email protected]>
Subject: Re: Identity class and parent/children entity relationship
To: [email protected]
Date: Monday, March 30, 2009, 9:56 AM
Thank you very much.

Nemanja J.

The second problem is a known problem. I will open a JIRA
for it.

--- On Sun, 3/29/09, Nemanja Joksovic
<[email protected]> wrote:

From: Nemanja Joksovic <[email protected]>
Subject: Identity class and parent/children entity

relationship

To: [email protected]
Date: Sunday, March 29, 2009, 5:33 AM
Hi all,

I've been experiencing few problems with Identity

class

and Parent/Children entity relationship. I tried with

both

OpenJPA 1.2.1 and 2.0.0-SNAPSHOT. I have a very simple

test

case which can briefly explain problems:

@Entity
public class Parent implements Serializable {

    private long id;
    ....
    private List<Child> children = new
LinkedList<Child>();

    @Id
//  @GeneratedValue(strategy =

GenerationType.IDENTITY)

    @Column(name = "id", unique = true,
insertable = false, updatable = false, nullable =

false)

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    ...

    @OneToMany(cascade = CascadeType.ALL, mappedBy =
"parent")
    public List<Child> getChildren() {
        return children;
    }

    public void addChild(Child child) {
        if (child == null) {
            throw new

IllegalArgumentException("Cannot

add a null Child");
        }
        this.getChildren().add(child);
    }

    public void setChildren(List<Child>

children) {

        this.children = children;
    }
}

@Entity
@IdClass(ChildId.class)
public class Child implements Serializable {

    private long id;
    ...
    private Parent parent;

    @Id
    @Column(name = "id", unique = false,

nullable

= false)
    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    ...

    @Id
    @ManyToOne
    @JoinColumn(name = "parent_id",
referencedColumnName = "id")
    public Parent getParent() {
        return parent;
    }

    public void setParent(Parent parent) {
        this.parent = parent;
    }
}

ChidId is generated with the Application Identity

Tool:

public class ChildId implements Serializable {
    ...
    public long id;
    public long parent;
    ...
}

1) Merge operation fail in any case with following
exception:

java.lang.NullPointerException
    at

net.company.persistence.Child.pcCopyKeyFieldsFromObjectId(Child.java)

at

net.company.persistence.Child.pcNewInstance(Child.java)

at

org.apache.openjpa.kernel.AttachStrategy.persist(AttachStrategy.java:93)

at

org.apache.openjpa.kernel.VersionAttachStrategy.attach(VersionAttachStrategy.java:100)

at

org.apache.openjpa.kernel.AttachManager.attach(AttachManager.java:241)

at

org.apache.openjpa.kernel.AttachStrategy.attachCollection(AttachStrategy.java:333)

at

org.apache.openjpa.kernel.AttachStrategy.replaceList(AttachStrategy.java:359)

at

org.apache.openjpa.kernel.AttachStrategy.attachField(AttachStrategy.java:223)

at

org.apache.openjpa.kernel.VersionAttachStrategy.attach(VersionAttachStrategy.java:153)

at

org.apache.openjpa.kernel.AttachManager.attach(AttachManager.java:241)

at

org.apache.openjpa.kernel.AttachManager.attach(AttachManager.java:101)

at

org.apache.openjpa.kernel.BrokerImpl.attach(BrokerImpl.java:3212)

    ... 25 more


The problem is caused by the call
pc.NewInstance(AttachStrategy:93) with null state

manager

instance which is used in

pcCopyKeyFieldsFromObjectId(..):

pcsetParent((Parent)pcStateManager.getPCPrimaryKey(childid,

2 + pcInheritedFieldCount));

Also, for same problem exists JIRA Issue:
https://issues.apache.org/jira/browse/OPENJPA-218


2) Persist working fine, but it's fail in the case

when

Parent.id is Generated Value field with following

exception:

<openjpa-1.2.1-r752877:753278 fatal user error>
org.apache.openjpa.persistence.InvalidStateException:
Detected reentrant flush.  Make sure your flush-time
instance callback methods or event listeners do not

invoke

any operations that require the in-progress flush to
complete.
    at

org.apache.openjpa.kernel.BrokerImpl.flushSafe(BrokerImpl.java:1904)

at

org.apache.openjpa.kernel.BrokerImpl.flush(BrokerImpl.java:1679)

at

org.apache.openjpa.kernel.StateManagerImpl.assignObjectId(StateManagerImpl.java:524)

at

org.apache.openjpa.kernel.StateManagerImpl.assignObjectId(StateManagerImpl.java:506)

at

org.apache.openjpa.kernel.StateManagerImpl.fetchObjectId(StateManagerImpl.java:1434)

at

net.company.persistence.Parent.pcFetchObjectId(Parent.java)

at

net.company.persistence.Child.pcCopyKeyFieldsToObjectId(Child.java)

Does exists some workaround for these problems ?

Regards,
Nemanja J.
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