[JBoss-user] [JBoss Seam] - Re: Entities with one/many_to_many relationships and SEAM

[petemuir <do-...@jb...>]

I'm sorry, I'm not quite sure what you mean.

The @SelectItems annotation (mine, not Jim's) in concert with the EntityConverter allows you to select multiple objects (from a generated list) and set them 'directly' (via the value attribute) as a collection on any object.

The only caveat is that the objects being selected MUST be entities which have been previously persisted (as it uses the @Id annotation as the identifier).  I don't think it will work for composite foreign keys either. 

Othewise you'll need to write a converter for that specific case.  I've got some ideas for a non-entity generic converter but tbh I can't really think of many situations where a combination of PAGE scope and Strategy.INDEX or Strategy.STRING don't work.

So you can do


  | <h:selectManyListbox value="#{x.yList} converter="org.jboss.seam.EntityConverter">
  |    <f:selectItems value="#{yList}" />
  | </h:selectManyListbox>
  | 


  | @Name("yLister")
  | @Stateless
  | public class YListerBean implements YLister {
  | 
  |    @SelectItems
  |    private List<Y> yList;
  | 
  |    @In(create=true)
  |    private EntityManager em;
  | 
  |    @Factory("yList")
  |    public void buildYList() {
  |       yList = em.createQuery("select y from Y y").getResultList();
  |    }
  | 
  | }
  | 

where YLister is an interface declaring public void buildYList() and the entity classes x and y are as you describe and there is a FormActionBean for loading x.

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