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EntityManager refresh problem

Hi, in the following code you can see an example with EntityManager.refresh(). The example throws ... -------------------- package example; import java.io.File; import javax.persistence.EntityManager; import ... void refreshTest() {         EntityManager entityManager = null;         try

Working with JPA Entity Objects

this state the object is not yet associated with an EntityManager and has no representation in ... via an EntityManager’s persist method, which must be invoked within an active transaction. On transaction commit, the owning EntityManager stores the new entity object to the database. More details on storing objects

Updating JPA Entity Objects

entity object from within an active transaction. No EntityManager's method is invoked to report

Setting and Tuning of JPA Queries

on which they were invoked). Flush Mode (setFlushMode) Changes made to a database using an EntityManager ... of other EntityManager instances). JPA implementations can easily make uncommitted changes visible in ... the application, either at the EntityManager level as a default for all the queries in that EntityManager

CRUD Database Operations with JPA

Given an EntityManager, em, that represents a JPA connection to the object database, we can use ... an ordinary Java object. It then becomes associated with an EntityManager and with its transaction (as ... can become productive very quickly. The EntityManager object serves as the factory for Query instances

Shared (L2) Entity Cache

Every EntityManager owns a persistence context, which is a collection of all the entity objects ... an entity object that is already managed by the EntityManager returns the existing instance from ... is one EntityManager. This section describes a level 2 (L2) cache of entity objects, which is managed

CRUD Operations with JPA

Explains how to use JPA for CRUD database operations (persist, retrieve, update, remove).

Deleting JPA Entity Objects

Explains how to use JPA to delete (remove) entity objects from the database.

Chapter 3 - Using JPA

Explains how to store, retrieve, update and delete entity objects using JPA.

JPA Reference (JavaDoc)

Java/JPA API Reference (based on the JPA 3 JavaDoc)

Getting Started

ObjectDB is very easy to use. Follow the Getting Started Tutorial and the Quick Tour manual chapter and in minutes you may be able to write and run first Java programs against ObjectDB.

Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.

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