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From "Pinaki Poddar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (OPENJPA-245) Attach NEW and auto-increment identity
Date Tue, 29 May 2007 17:20:16 GMT

    [ https://issues.apache.org/jira/browse/OPENJPA-245?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12499851
] 

Pinaki Poddar commented on OPENJPA-245:
---------------------------------------


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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