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Re: [eclipselink-users] Defining persistence.xml programmatically?

Hi Tim,

Tim Hollosy wrote:
Thanks Dough & Shaun,
The properties map worked fine, the only issue we had was using:

<persistence-unit name="unit-name">

With that set, I cannot create an Entity Manager, I get an error
saying it can't find the database driver (PostgreSQL), however if I
just define my classes in my persistence.xml like this:

<persistence-unit name="unit-name">

It works fine.

Why you can't find your driver is a mystery but I think you're running into some issues due to classloader behavior in Equinox.  I hadn't tried any examples with <exclude-unlisted-classes>false</exclude-unlisted-classes> but as I learn more I see this may require special support.  This is something we'll have to look into once we get the main branch switched over to OSGi.
On top of that, it will only work if I create my Entity Manager like this:
emf = new PersistenceProvider().createEntityManagerFactory("unit-name",

If I try to do it like in the examples, using the static method:

emf = Persistence.createEntityManagerFactory("unit-name", properties);

It will not work, throwing a PersistenceException "No Persistence
provider for EntityManager named  unit-name".

In the Proof of Concept there are three ways to create an EntityManagerFactory.  The one you're using is the easiest in that it passes the classloader that can load all the necessary classes directly to the EclipseLink persistence provider and avoids the need for javax.persistence.Peristence to locate it.  If you want to invoke Persistence.createEntityManagerFactory you'll need to follow the steps outlined on the section Creating a JPA application bundle using the standard JPA SPI. When doing this you have to make sure you have the start  levels set so that EclipseLink JPA is initialized before you try to use it in application code.
I can mostly live with creating my em the other way, however it would
be nice to get auto discovery of classes to work.
I'm working on it in conjunction with enabling byte code weaving in Equinox. ;-)  This is a ways off so hopefully you can live with listing the classes for now.  I expect we'll see a big improvement in the ease of use as we transition over to OSGi in EclipseLink and we get more experience with it.

Thanks again,

On Mon, Mar 31, 2008 at 12:43 PM, Doug Clarke <douglas.clarke@xxxxxxxxxx> wrote:

 You can definitely avoid putting any database login information in your EclipseLink configuration files. I have recently blogged about a common framework I use for testing JPA outside of a container. This will work as well for any JavaSE or RCP application usage where the additional properties are passed in through a properties map to the Persistence.createEntitymanagerFactory call.

 On Friday night I moved some of this content into the EclipseLink wiki example pages to make it more available.

 I hope this addresses your issue,


 -----Original Message-----
 From: eclipselink-users-bounces@xxxxxxxxxxx
 [mailto:eclipselink-users-bounces@xxxxxxxxxxx]On Behalf Of Tim Hollosy
 Sent: Monday, March 31, 2008 11:49 AM
 To: eclipselink-users@xxxxxxxxxxx
 Subject: [eclipselink-users] Defining persistence.xml programatically?

 I'm looking into using EclipseLink in an RCP application, and for
 obvious reason's i'm not keen on distributing my database login info
 in an xml file.

 I'd like to define it programatically in java, however all the
 documentation I can find just talks about defining a project.xml or

 Has anyone done this?

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