[jboss-user] [EJB 3.0] - Re: onetomany relationship question

Wolfgang Knauf do-not-reply at jboss.com
Tue Jul 7 05:18:58 EDT 2009


Q1: for each child, you have to do this:
    ParentBean parent = ...;    
  |     ChildBean child1 = ...;
  | ==> parent.getChilds().add (child1);
  |     child1.setParent(parent);
Otherwise, the relation will not be saved, but there will be no error message.

Q2: I don't know what is happening if you call "setChilds" before loading them, but I would expect strange side effects at least when the collection is under EntityManager control (inside a session bean method/transaction). So better manipulate the collection returned by "getChilds" and add/remove items. I will give this a try in the next few days and update my Wiki if I find a "No go".

Q3: Did you activate SQL query logging in your persistence.xml? 
	<?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"
  | 		xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
  | 		version="1.0">
  | 		<persistence-unit name="..">
  | 			...
  | 			<properties>
  | 				...
  | ===>				<property name="hibernate.show_sql" value="true"></property>
  | 			</properties>
  | 		</persistence-unit>
  | 	</persistence> 
But I am not sure how the childs are loaded. I will take a look at the JBoss console when I near a computer with JBoss  ;-)

Best regards


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