Entity enhancement fails while using EmbeddedId on a MappedSuperclass

• Key: OPENJPA-146
• Type: Bug
• Status: Resolved
• Resolution: Fixed
• Priority: Major
• Assignee: Unassigned
• Reporter: Gokhan Ergul
• Component/s: kernel
• Fix Version/s: 0.9.7

Description

Both buildtime and runtime class enhancement fail with the following error:

...
1339 TRACE [main] openjpa.Enhance - Enhancing type "class test.B".
Exception in thread "main" <0|false|0.9.6-incubating> org.apache.openjpa.util.GeneralException: null
        at org.apache.openjpa.enhance.PCEnhancer.run(PCEnhancer.java:350)
        at org.apache.openjpa.enhance.PCEnhancer.run(PCEnhancer.java:3711)
        at org.apache.openjpa.enhance.PCEnhancer.run(PCEnhancer.java:3661)
        at org.apache.openjpa.enhance.PCEnhancer.main(PCEnhancer.java:3633)
Caused by: java.lang.NullPointerException
        at org.apache.openjpa.enhance.PCEnhancer.enhanceObjectId(PCEnhancer.java:2745)
        at org.apache.openjpa.enhance.PCEnhancer.run(PCEnhancer.java:338)
        ... 3 more

Test code as follows:

test/A.java:
--------------
package test;

import javax.persistence.*;
import java.io.Serializable;

@MappedSuperclass
abstract public class A {

    @Embeddable
    public static class A_PK implements Serializable {
        @Basic
        protected int id1;
        
        @Basic
        protected String id2;
        
        public boolean equals (Object other) {
            return false;
        }

        public int hashCode () {
            return 0;
        }

    }

    @EmbeddedId
    protected A_PK pk;

    @Basic
    protected String val;

}
--------------

test/B.java:
--------------
package test;

import javax.persistence.Entity;

@Entity
public class B extends A {

}
--------------

META-INF/persistence.xml:
--------------
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
        version="1.0">
    <persistence-unit name="TestService" transaction-type="RESOURCE_LOCAL">
        <class>test.A$A_PK</class>
        <class>test.A</class>
        <class>test.B</class>
        <properties>
            <property name="openjpa.Log" value="DefaultLevel=TRACE"/>

            <property name="openjpa.ConnectionUserName" value="test"/>
            <property name="openjpa.ConnectionPassword" value="test"/>
            <property name="openjpa.ConnectionURL" value="jdbc:mysql://localhost:3306/oam?useServerPrepStmts=false"/>
            <property name="openjpa.ConnectionDriverName" value="com.mysql.jdbc.Driver"/>
        </properties>
    </persistence-unit>
</persistence>
--------------

Comments

Test case and trace output attached.

[Abe White]

We don't enhance the oid class anymore, so this bug is probably fixed or at least will manifest itself in a different way in the latest code.

[Gokhan Ergul]

0.9.7-snapshot seems to have solved this indeed, thanks.

[Gokhan Ergul]

Alright, it did manifest itself in a different way as you guessed:

java.lang.NullPointerException
at org.apache.openjpa.jdbc.meta.strats.EmbedValueHandler.map(EmbedValueHandler.java:50)
at org.apache.openjpa.jdbc.meta.strats.ObjectIdValueHandler.map(ObjectIdValueHandler.java:46)
at org.apache.openjpa.jdbc.meta.strats.HandlerStrategies.map(HandlerStrategies.java:56)
at org.apache.openjpa.jdbc.meta.strats.HandlerFieldStrategy.map(HandlerFieldStrategy.java:77)
at org.apache.openjpa.jdbc.meta.FieldMapping.setStrategy(FieldMapping.java:117)
...

Bit of debugging into the code:

(EmbedValueHandler.java)
    protected void map(ValueMapping vm, String name, ColumnIO io,
        boolean adapt, List cols, List args) {
        // have to resolve embedded value to collect its columns
        vm.getEmbeddedMapping().resolve(vm.MODE_META | vm.MODE_MAPPING);
...

vm .getEmbeddedMapping() returns null, since:

(ValueMetaDataImpl.java)
    public ClassMetaData getEmbeddedMetaData() {
        if (_embeddedMeta == null && isEmbeddedPC())
            addEmbeddedMetaData();
        return _embeddedMeta;
    }

and

    public boolean isEmbeddedPC() {
        return _decCode == JavaTypes.PC && isEmbedded();
    }

_decCode is JavaTypes.OID.

JavaTypes.PC was possibly overwritten by:

    public boolean resolve(int mode) {
...
        // oid as primary key field?
        if (_decCode == JavaTypes.PC && isEmbedded()
            && _owner.isPrimaryKey() && _owner.getValue() == this)
            _code = _decCode = JavaTypes.OID;

So I've changed

    public boolean isEmbeddedPC() {
        return _decCode == JavaTypes.PC && isEmbedded();
    }

to

    public boolean isEmbeddedPC() {
        return (_decCode == JavaTypes.PC || _decCode == JavaTypes.OID) && isEmbedded();
    }

seems to have fixed the problem, tho I'm not sure if it has any nasty sideeffects.

Any comments?

[Abe White]

Looks like a good fix to me. Do you need someone to commit this for you?

[Abe White]

Cancel my previous comment. Embedded PCs are handled very differently than OIDs at runtime, and so changing the isEmbeddedPC method to encompass OIDs as well might cause problems. I think the root of the problem has to do with metadata resolution of mapped superclass fields (after all, EmbeddedIds in Entities work fine, just not in MappedSuperclasses). I'll investigate further.

[Abe White]

Resolved with revision 509632. When copying OID superclass fields for mapping in a subclass, revert the type of the field to PC. It will re-resolve to OID when the copied field's metadata is resolved, and in the meantime it ensures that the copied field resolution will use the same code path as non-copied fields.

[Gokhan Ergul]

Fix confirmed, thanks.