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From "Pinaki Poddar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (OPENJPA-245) Attach NEW and auto-increment identity
Date Wed, 30 May 2007 20:58:15 GMT

    [ https://issues.apache.org/jira/browse/OPENJPA-245?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12500235
] 

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

An entity instance x which has been created by new() operator and carrying a existing id (say
idx) set by the user application is treated as detached by merge() when the entity class is
annotated with @DetachState(enabled=false). Then merge() updates the existing database record
with current state of x. If it is not annotated with @DetachState(enabled=false), the instance
x is trated as a new instance, and if the entity is using auto-generated identity, a new database
record is created, ignoring the id set by the application. However, if the entitymanager doing
the merge() is already managing an instance with the same identity idx then an EntityExists
exception is raised. 

The generated enhanced code differs based on @DetachedState setting. 
So if the application has changed this setting, the entity must be enhanced again.   




> 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
>         Attachments: TestMerge.zip
>
>
> 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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