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https://issues.apache.org/jira/browse/OPENJPA-245?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12499851
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Pinaki Poddar commented on OPENJPA-245:
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merge() to identify that the the merged entity instance is not *truely* new but
a version of a instance that is already persistent, the entity requires a
version field.
If the merged instance was a clone created out of serialization and
desrialization, then OpenJPA will maintain the required bits to identify the
difference between a truly new instance and an instance that has been detached.
> Attach NEW and auto-increment identity
> --------------------------------------
>
> Key: OPENJPA-245
> URL: https://issues.apache.org/jira/browse/OPENJPA-245
> Project: OpenJPA
> Issue Type: Bug
> Components: jpa
> Affects Versions: 0.9.6, 0.9.7
> Environment: jdk1.5.0_11, Win XP, Fedora Core 6, Postgres 8.1 (on
> Fedora)
> Reporter: Aleksandar Likic
>
> According to documentation (1.2 Attach Behavior), when an entity instance is
> NEW (never detached):
> * If neither of the above cases apply, OpenJPA will check to see if an
> instance with the same primary key values exists in the database. If so, the
> object is considered detached. Otherwise, it is considered new.
> This doesn't work for me - a new record in database is created on commit
> instead of updating the existing one. The "regular" case -
> detach/modify/attach works fine - the existing record is updated.
> It is very easy to reproduce - just create a new instance of an entity,
> assign an already existing primary key, call em.merge() and commit. A new
> record will be created in database, with new, auto-generated primary key.
> I stumbled on this trying to implement a web service that uses OpenJPA-based
> backend. When servicing an "update" request, the web service instantiates a
> NEW object (by performing XML de-serialization) and calls em.merge to update
> the entity. A new record gets created instead of updating an existing one.
> ------------ Entity class (START) ------------------------------
> package exaple;
> public class Consumer implements java.io.Serializable {
> private long id;
> public long getId() {
> return this.id;
> }
> public void setId(long id) {
> this.id = id;
> }
> private java.lang.String firstName;
> public java.lang.String getFirstName() {
> return this.firstName;
> }
> public void setFirstName(java.lang.String firstName) {
> this.firstName = firstName;
> }
> private java.lang.String lastName;
> public java.lang.String getLastName() {
> return this.lastName;
> }
> public void setLastName(java.lang.String lastName) {
> this.lastName = lastName;
> }
> ------------ Entity class (END) ------------------------------
> ------------ persistence.xml (START) ------------------------------
> <?xml version="1.0" encoding="UTF-8"?>
> <persistence xmlns="http://java.sun.com/xml/ns/persistence";
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; version="1.0">
> <persistence-unit name="example" transaction-type="RESOURCE_LOCAL">
>
>
> <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
> <!-- We must enumerate each entity in the persistence unit -->
> <class>example.Consumer</class>
> <properties>
> <property name="openjpa.jdbc.DBDictionary" value="postgres"/>
> <property name="openjpa.ConnectionDriverName"
> value="org.postgresql.Driver"/>
> <property name="openjpa.ConnectionUserName" value="app_user"/>
> <property name="openjpa.ConnectionPassword" value="app_user"/>
> <property name="openjpa.ConnectionURL"
> value="jdbc:postgresql://localhost/alikic"/>
> <property name="openjpa.Log" value="DefaultLevel=WARN,SQL=TRACE"/>
>
> </properties>
> </persistence-unit>
>
> </persistence>
> ------------ persistence.xml (END) ------------------------------
> ------------ orm.xml (START) ------------------------------
> <entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm";
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
> xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm
> orm_1_0.xsd"
> version="1.0">
> <entity class="example.Consumer">
> <attributes>
> <id name="id">
> <generated-value strategy="IDENTITY"/>
> </id>
> <basic name="firstName">
> <column name="first_name"/>
> </basic>
> <basic name="lastName">
> <column name="last_name"/>
> </basic>
> </attributes>
> </entity>
> </entity-mappings>
> ------------ orm.xml (END) ------------------------------
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