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From Marc Prud'hommeaux <>
Subject Re: Getting all the ClassMetaDatas
Date Tue, 02 Jan 2007 00:18:45 GMT

Have you already obtained an EM from the EMF before you make this  
call? If you try to get the metadatas after calling  
emf.getEntityManager(), do you still see an empty list?

Also, note that unless you enumerate the classes in your  
persistence.xml file (in the <class> elements), the only way the  
system will be able to know about your classes before they are lazily  
evaluated is if you enable one of the scanning features (e.g., but  
packaging all your classes in a jar and specifying the <jar-file>  
element in the persistence.xml, which will be automatically scanned  
for persistent classes).

You might want to enable verbose logging and watch the make sure the  
class metadatas are registered before you try to get the list from  
the repository.

On Jan 1, 2007, at 4:11 PM, Shay Banon wrote:

> Hi,
>    First, I hope that this is the correct forum for posting  
> questions, so
> sorry if it isn't.
> I have an external list of classes that I would like to match  
> against the
> persistent classes that are defined/identified by OpenJPA. I would  
> really
> like to get the ClassMetaData for each one, since it has a lot of
> information that I could use. This intersection happens after the
> EntityManagerFactory has been created.
> I have tried using:ClassMetaData[] classMetaDatas =
> emf.getConfiguration().getMetaDataRepositoryInstance().getMetaDatas();
> But it seems like the meta data repository and ClassMetaData  
> information are
> lazily loaded (i.e. when some operation is performed on a Class, the
> relevant meta data is fetched if not found in cache). So, what I  
> get is an
> empty array (even though I can see the OpenJPA identified the  
> classes).
> I wonder how I would be able to get all the class meta data?
> Something that I was thinking about is since I have the list of  
> classes that
> I would like to check if they are persistent, I could call:
> getMetaData(Class cls, ClassLoader envLoader, boolean mustExist), with
> Thread context class loader and false in mustExists. I am guessing  
> that it
> will load the ClassMetaData if not found. My main problem here is that
> OpenJPA might be configured with a different class loader (though it
> defaults to the thread context one).
> Any suggestions?
> p.s.
> I am the author of Compass, so once I have this nailed down, we  
> will have
> Search capabilities to OpenJPA ;)
> -- 
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> ClassMetaDatas-tf2905426.html#a8116958
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