A.v A.v - 1 year ago 83
Java Question

Do Jpa& Hibernate load data which changes asynchronously in DB?

I have an oracle view in which I query my db.

create or replace view my_view as
Select cc.CCID ccid
sm.SMCODE smcode,
NVL(sm.smname, cc.ccname) sname
From CC cc
Inner Join SM sm
On cc.id = sm.id;

I use
jpa 2.1
hibernate 4.3.7
to map my view to my entity.
My entity class looks like this:

public class CCRequest implements Serializable {

private static final long serialVersionUID = 1L;

private String ccId;

private String smCode;

private String sName;

And my mapping xml looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<entity-mappings xmlns="http://xmlns.jcp.org/xml/ns/persistence/orm"
<entity class="CCRequest" name="CCRequest001">
<table name="my_view"/>
<id name="ccId">
<column name="ccid"/>
<basic name="smCode">
<column name="smcode"/>
<basic name="sName">
<column name="sname"/>

So I query my entity with jpa properly and it returns all my records.
Here is the problem, when I change my data in DB asynchronously, Shockingly my jpa query returns previous records.
Have I done something wrong?

A.v A.v
Answer Source

The problem I was facing was that in spring before 4, which we had JpaTemplate for working with jpa entities, I passed EntityManager to the instances of JpaTemplate programmatically from an instance of EntityManagerFactory with no problem.

JpaTemplate itself would do any thing for flushing EntityManager and clearing cache. When I migrate to spring 4 I faced that JpaTemplate has been dropped so I have to work with EntityManager directly.

I get instance of EntityManager programmatically from an instance of EntityManagerFactory.

I have a EntityManagerProvider class which create an instance of EntityManager from an instance of EntityManagerFactory.

public class EntityManagerProvider {

    public static EntityManager createEntityManager(EntityManagerFactory entityManagerFactory) {
        return entityManagerFactory.createEntityManager();

I get entityManager instance like this:

<bean id="entityManager" class="com.tosan.novin.sipa.bo.da.jpa.EntityManagerFactoryProvider" factory-method="createEntityManager">
        <constructor-arg index="0" ref="entityManagerFactory"/>

But I understand that if I want EntityManager to manage transactions and flushing the only way is use of @PersistenceContext for injecting EntityManager into my beans.

protected EntityManager em;

I am a little confused yet with this manner but my problem solved with this approach.

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