JPA @version - can it be used to calcualate version of a table entry

Posted by OpenSource on Stack Overflow See other posts from Stack Overflow or by OpenSource
Published on 2010-05-20T19:36:41Z Indexed on 2010/05/20 19:40 UTC
Read the original article Hit count: 220

Filed under:

ejb3

|

jpa

|

java

|

java-ee

Hi,

Please consider the following table (created using a corresponding entity)

request
-------
id requestor type version items 
1  a         t1   1        5
2  a         t1   2        3
3  b         t1   1        2
4  a         t2   1        4
5  a         t1   3        9

The above is what I want to achieve. The version field is a calculated field others are user provided. Basically the request's version needs to be calculated based on the combination of requestor and the type. The first occurance with a given combination will have a version 1 then version 2 and so on.

I tried various things using @version on a different entity with just the three columns and joining the two entities using ManytoOne etc but I'm not able to get to the desired outcome. I dont want to confuse you with the things I tried.

Since the objective is simple there should be an easier way I suppose? Can you please help? - any help greatly appreciated!

thanks in advance

© Stack Overflow or respective owner

Related posts about ejb3

Error in Jboss 5- DEPLOYMENTS MISSING DEPENDENCIES

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi! I'm new to ejb3. I tried deploying a simple war file.. But, I'm getting the following error. Plz, help me... DEPLOYMENTS MISSING DEPENDENCIES: Deployment "jboss.j2ee:jar=EJB3-war.war,name=Statelessbean,service=EJB3_endpoint" is missing the following dependencies: Dependency "jboss… >>> More
logback with EJB3.1

as seen on Stack Overflow - Search for 'Stack Overflow'
I am using logback/slf4j to handle logging in my application. Everything was working perfectly until I started using EJBs. Once I added a stateless EJB to my app, the logger started ignoring my logback.xml and stopped using my appenders. I switched to a programmatic logger configuration to see what… >>> More
EJB3 Remote vs Webservices, performances?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello I'm planning to a webapp where every guy using it would have a client that would run computations on its computer (because these computations can't be done on the server, too much load...), and then send results to the server. I guess there will be lot of people interested in my application… >>> More
Best current framework for unit testing EJB3 / JPA

as seen on Stack Overflow - Search for 'Stack Overflow'
Starting new project using EJB 3 / JPA, mainly stateless session beans and batch jobs. I've used JUnit in the past on standard Java webapps and it seemed to work pretty well. In EJB2 unit testing was a pain and required a running container such as JBoss to make the calls into. Now that we're going… >>> More
Problem in creation MDB Queue connection at Jboss StartUp

as seen on Stack Overflow - Search for 'Stack Overflow'
I am not able to create a Queue connection in JBOSS4.2.3GA Version & Java1.5, as I am using MDB as per the below details. I am putting this MDB in a jar file(named utsJar.jar) and copied it in deploy folder of JBOSS, In the test env. this MDB works well but in another env. [ env settings and… >>> More

Related posts about jpa

Detach an entity from a JPA persistence context (JPA 2.0 / Hibernate / EJB 3 / J2EE 6)

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I wrote a stateless EJB method allowing to get an entity in "read-only" mode. The way to do this is to get the entity with the EntityManager then detach it (using the JPA 2.0 EntityManager). My code is the following: @PersistenceContext private EntityManager entityManager; public T getEntity(int… >>> More
AndroMDA maven code generation and JPA Annotations

as seen on Stack Overflow - Search for 'Stack Overflow'
I am using the AndroMDA plugin for maven to generate code from an uml diagram made in MagicDraw. When the code is generated, AndroMDA desings the JPA annotation for the persitence layer. I think that at the compilation process AndroMDA uses Naming Strategies to determine the Table and Column names… >>> More
How to populate Java (web) application with initial data using Spring/JPA/Hibernate

as seen on Stack Overflow - Search for 'Stack Overflow'
I want to setup my database with initial data programmatically. I want to populate my database for development runs, not for testing runs (it's easy). The product is built on top of Spring and JPA/Hibernate. Developer checks out the project Developer runs command/script to setup database with initial… >>> More
Eclipselink problem in a javase project

as seen on Stack Overflow - Search for 'Stack Overflow'
I am getting this error when I am running my eclipselink project. [EL Warning]: 2008.12.05 11:47:08.056--java.lang.NoClassDefFoundError: org/jboss/resource/adapter/jdbc/ValidConnectionChecker was thrown on attempt of PersistenceLoadProcessor to load class com.mysql.jdbc.integration.jboss.MysqlValidConnectionChecker… >>> More
JPA thinks I'm deleting a detached object

as seen on Stack Overflow - Search for 'Stack Overflow'
So, I've got a DAO that I used to load and save my domain objects using JPA. I finally managed to get the transaction stuff working (with a bunch of help from the folks here...), now I've got another issue. In my test case, I call my DAO to load a domain object with a given id, check that it got… >>> More