jsr338-experts@jpa-spec.java.net

[jsr338-experts] Re: _at_OneToOne(optional=true) and @PrimaryKeyJoinColumn

From: Rainer Kwesi Schweigkoffer <kwesi_at_sap.com>
Date: Mon, 05 Sep 2011 17:20:27 +0200

Hi Emmanuel, all,

Emmanuel Bernard, am 2 Sep 2011 hast Du um 10:51 zum Thema "[jsr338-experts] @OneToOne(optional=true) and @Pr" geschrieben :

> @Entity
> class User {
> @Id String username;
>
> @OneToOne(optional=true) @PrimaryKeyJoinColumn
> Profile getProfile() { ... };
> }
 
> But elsewhere the spec mention the need to have foreign keys (in general).

I'd favour to explicitly state that in the above case that no foreign
key is created, but could also live with a statement that the
combination of optional=true and @PrimaryKeyJoinColumn is not portably
supported.

In the derived entity case the relationship becomes part of the id and,
hence, to my understanding may not be null.

With respect to
http://lists.jboss.org/pipermail/hibernate-dev/2011-August/006980.html
I have not fully understood the distinction between generated and user-
defined ids. Why would the fact that a user id was generated require
the user to have a profile ?

Kind regards
Rainer




---
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