Hello folks. Once again I have some questions, this time about EJB QL.
The quick version is: How sophisticated is the current Orion support
for EJB QL? I want to define a finder query on a field which is the
mapping field of a CMR relationship, but it doesn't seem to work.
Here's the long version:
I'm using EJB 2.0 CMR fields to map a relationship between two entity
beans, called Member and MemberName. The primary key for the MemberName
is (not surprisingly) a string, and every Member has a MemberName as
defined by the following relation:
<ejb-relation>
<ejb-relation-name> Member-canonical-MemberName </ejb-relation-name>
<description>
This is a unidirectional one-to-one mapping from Member
to MemberName. Members have a single canonical MemberName.
</description>
<ejb-relationship-role>
<ejb-relationship-role-name> Member-has-canonical-MemberName
</ejb-relationship-role-name>
<multiplicity> one </multiplicity>
<role-source> <ejb-name> MemberEJB </ejb-name> </role-source>
<cmr-field> <cmr-field-name> memberName </cmr-field-name>
</cmr-field>
</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name> MemberName-is-canonical-for-Member
</ejb-relationship-role-name>
<multiplicity> one </multiplicity>
<role-source> <ejb-name> MemberNameEJB </ejb-name> </role-source>
</ejb-relationship-role>
</ejb-relation>
Just a quick side-note, which I think was brought up before: the EJB2.0
spec (pd2) seems to indicate that the cmr-fields should _not_ also be
defined as cmp-fields in the entity descriptor. Orion 1.3.8 seems to
require this. In any case...
The table which is created for Member has the memberName field which is
of course a string (the MemberName's primary key). Good. Now I want a
finder method on MemberHome which is
public Member findByName(String name);
I can imagine two ways of going about this. The simple one would be to
pretend that Member's memberName is a cmp-field. The query would be:
<query>
<query-method>
<method-name> ejbFindByName </method-name>
<method-params>
<method-param> java.lang.String </method-param>
</method-params>
</query-method>
<ejb-ql> FROM MemberEJB memb WHERE memb.memberName = ?1 </ejb-ql>
</query>
While this works for actual cmp-fields, this does not seem to work for
cmr-fields. Not surprising, since the spec doesn't mention this as an
option (although it doesn't eliminate it, either).
The "proper" way to write the query, if I'm reading the spec right, is:
<query>
<query-method>
<method-name> ejbFindByName </method-name>
<method-params>
<method-param> java.lang.String </method-param>
</method-params>
</query-method>
<ejb-ql> FROM MemberEJB memb, n IN memb.memberName WHERE n.name = ?1
</ejb-ql>
</query>
But I'm not wholly certain, because all the relational EJB QL examples
in the spec are for one-to-many relationships, not one-to-one. In any
case, when I try this, I get the same results that I do for the first
query, which is to say wholly incorrect results :-) The failure mode is
bad, too; rather than failing to find the Member, it seems to just
return a random existing Member.
So am I just pushing the edge of Orion's implementation of the EJB2.0
spec, or am I defining my queries wrong? If this is heading into
unimplemented space, should I log bugs in Bugzilla or just assume that
the authors are busily working on this very problem and don't need yet
another monkey on their backs? :-)
Is anyone else working with EJB2.0 beans?
Thanks,
Jeff Schnitzer
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
