James,
I tried your mapping in the Modeler and I don't seem to have any problems,
regardless of whether I have "NodeMap" in the model or not. Are you having
trouble with this panel?
http://objectstyle.org/cayenne/images/modelerguide/objrelationship-path-selection.jpg
One thing I noticed (this should show up as a validation message on save)
is that node_map has no PK defined. You need to check both columns as PK
as "childNodeMapArray" and "parentNodeMapArray" relationships as "To Dep
PK".
Andrus
> Hi, I'm new to Cayenne. I have a question about many-to-many
> relationships, specifically how to relate an object back to it's own
> type.
>
> I want to have a model of generic "Node" objects, each which can have
> 0-many children (and implicitly 0-many parents).
>
> Here is a sample database schema definition (for PostgreSQL, but should
> be pretty generic):
>
> create table node (
> node_id bigint not null,
> name varchar(40) not null,
> primary key (node_id)
> );
>
> create table node_map (
> parent_node_id bigint not null,
> child_node_id bigint not null
> );
>
> alter table node_map
> add constraint node_map_parent_fk foreign key (parent_node_id)
> references node (node_id);
>
> alter table node_map
> add constraint node_map_child_fk foreign key (child_node_id)
> references node (node_id);
>
>
> After reverse engineering this schema I played around with the modeler
> some, and was having a lot of trouble "flattening" the relationship.
> Things are really confusing since everything is a Node! It seems like
> things snap into place when I delete the "NodeMap" object entity - did I
> have to do that first?
>
> I'm attaching my project/map files, maybe someone could take a look at
> them and tell me if I did things right? Also will Cayenne be able to
> keep both the child and parent arrays in sync, or do I need to have just
> a child array?
>
> One more question... what is the Data View modeler for?
>
> Thanks!
>
> -james
>
> --
> James A. Hillyerd <jame..illyerd.com>
> Java Software Engineer - ActiveRain.com
This archive was generated by hypermail 2.0.0 : Fri Dec 10 2004 - 10:13:44 EST
