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Re: [eclipselink-dev] Loading multiple persistence.xml files
That works out fine.  Our system pulls in jars that are self contained projects.  I don't have a way to know what mapping files are available without querying the classloader.

e.g.
Sakai ClassLoader sees:
  project1.jar!META-INF/persistence.xml   <-- defines "default" UoW
  project1.jar!META-INF/orm.xml
  project2.jar!META-INF/persistence.xml   <-- also defines "default" UoW
  project2.jar!META-INF/orm.xml
etc.

The classloader "trick" I've seen is to query for all these files then inject into getResources() such that either, on-the-fly, 1) create a persistence.xml that contains a mapping entry for each orm.xml found or 2) merge all orm.xml files into 1 file and return a reference.


On Wed, Dec 17, 2008 at 11:07, Tom Ware <tom.ware@xxxxxxxxxx> wrote:
Hi Carl,

 What issues are you seeing when you specify several orm files within the same persistence unit definition in one persistence.xml file?

e.g.

<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 persistence_1_0.xsd" version="1.0">

   <persistence-unit name="default" transaction-type="RESOURCE_LOCAL">
       <provider>
           org.eclipse.persistence.jpa.PersistenceProvider
       </provider>

       <mapping-file>META-INF/advanced-entity-mappings.xml</mapping-file>
       <mapping-file>META-INF/inheritance-entity-mappings.xml</mapping-file-->
       <mapping-file>META-INF/inherited-entity-mappings.xml</mapping-file>
       <mapping-file>META-INF/relationships-entity-mappings.xml</mapping-file>


etc....


-Tom

Carl Hall wrote:
Hi, Tom.

You've nailed it.  Each persistence.xml is trying to create the same persistence unit ("default").  Is there a nice way to load 1 persistence unit from multiple orm.xml files?  I've seen some classloader tricks to accomplish this but don't want to head down that rabbit hole unless necessary.

Thanks,
Carl


On Wed, Dec 17, 2008 at 10:55, Tom Ware <tom.ware@xxxxxxxxxx <mailto:tom.ware@xxxxxxxxxx>> wrote:

   Hi Carl,

    Are you using separate EntityManagers for each persistence unit?

    An EntityManager represents one persistence unit - when the
   EntityManagerFactory is created, you get it by persistence unit
   name.  Any EntityManager created by that factory will represent that
   persistence unit.

    The name of a persistence unit is specified in the persistence.xml
   and only one persistence.xml may be used to define a given
   persistence units.  It is an error to have multiple persistence.xml
   that define the same persistence unit and the behavior is undefined
   - I am not surprised that if you are doing this, you get the last
   one loaded.

    To access different persistence units, create an EntityManager for
   each.

   -Tom

   Carl Hall wrote:

       I have a setup where multiple project come into a shared
       classloader.  Each project can have its own model files and
       thusly its own persistence.xml and orm.xml files.  When I create
       an EntityManager, I see in the logs that each persistence.xml
       file is found (3) and each orm.xml file loads with the expected
       entities.  When I try to query or persist using this
       EntityManager, only the entities from the lastly loaded
       persistence.xml is found.  Am I loading this correctly?  Am I
       trying to access things incorrectly?


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