Re: JPA and Collection valued Properties

"Kenneth P. Turvey" <>
21 Aug 2008 02:48:58 GMT
On Wed, 20 Aug 2008 19:35:58 -0700, Mark Space wrote:

Kenneth P. Turvey wrote:

This isn't really a problem for me, but it seems to be missing from the
text I have on the Java Persistence API. I have an entity that has a
field that is a collection, like so:

Which text are you referring to? I think it would help us to know what
work you've done on this yourself already. One Google search and two
clicks, I found this, which strongly seems to imply that a collection
will be (or can be) persisted:



"The Customer entity is mapped to the CUSTOMER table, and looks like

public class Customer {

     private int id;
     private String name;
     private Collection<Order> orders;

So there seems to be a couple of other tags in there too (later on in
the class def). I confess I didn't read the whole thing. BTW, here was
the first link Google gave, which is how I found the one above.


The text is "Pro EJB 3, Java Persistence API". I've done some searching
on Google without really coming to any strong conclusions.

I'll take a look at the link you provide above and see what it says.

[Time passes]

OK, this is the same kind of example that my text has. The difference is
that the collection referenced is a collection of other entities.
Entities that must be described in their own class. In addition this
class has the @OneToMany tag that makes this all work.

So if I just have a simple mapping like that above that I want treated
like any other member of my entity class, I'm not sure if the API allows
for that. Even if the implementation that I'm using handles it well (and
I'm not sure that it does yet), I can't be sure that it is a legal and
well behaved use of the API.

I was hoping somebody on this group would have the answers. I'm certain
I'm not the first person to wonder about this.

Kenneth P. Turvey <>

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