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Posted to ojb-user@db.apache.org by "McCaffrey, John G." <Jo...@kraft.com> on 2004/03/18 20:33:09 UTC

1 to 1 mapping

I am trying to join two tables A and B
table A has three primary keys
Main_ID
Node_ID
Process_Date

table B has two primary keys
Node_ID
Process_Date

my mapping has the Table A object containing a collection of B obj
I want to join the collection using the Node_ID, because it is the only
thing they can be joined on

when I do the mapping

<collection-descriptor name="aObj" element-class-ref="x.x.x.AObj"
proxy="false" auto-retrieve="true" > 
<inverse-foreignkey field-ref="node_ID"/>
</collection-descriptor>

it complains about an arrayIndexOutOfBounds 
but it works when the only primary key is Node_ID 

i don't get it


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Re: 1 to 1 mapping

Posted by Armin Waibel <ar...@apache.org>.
Hi John,

you have to declare all PK fields in the collection/reference-descriptor 
inverse-foreignkey/foreignkey tags.

McCaffrey, John G. wrote:
> I am trying to join two tables A and B
> table A has three primary keys
> Main_ID
> Node_ID
> Process_Date
> 
> table B has two primary keys
> Node_ID
> Process_Date
> 
> my mapping has the Table A object containing a collection of B obj

ok, you have an 1:n reference from A to B, thus your 
collection-descriptor should look like

<class-descriptor for A>
...
<collection-descriptor
name="allBs"
element-class-ref="B"
proxy="false"
auto-retrieve="true" >
   <inverse-foreignkey field-ref="FK_node_ID"/>
   <inverse-foreignkey field-ref="FK_main_ID"/>
   <inverse-foreignkey field-ref="FK_process_date"/>
</collection-descriptor>
...
</class-descriptor>

Means your B class needs three FK fields (to map the PK of A).

regards,
Armin

> I want to join the collection using the Node_ID, because it is the only
> thing they can be joined on
> 
> when I do the mapping
> 
> <collection-descriptor name="aObj" element-class-ref="x.x.x.AObj"
> proxy="false" auto-retrieve="true" > 
> <inverse-foreignkey field-ref="node_ID"/>
> </collection-descriptor>
> 
> it complains about an arrayIndexOutOfBounds 
> but it works when the only primary key is Node_ID 
> 
> i don't get it
> 
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
> 
> 
> 

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Re: 1 to 1 mapping

Posted by Edson Carlos Ericksson Richter <ed...@mgrinformatica.com.br>.
Use a reference-descriptor to make 1:1 mappings. If you are using 1:N mappings, use a collection-descriptor in the 1 side, and a reference-descriptor in the N side.

Best regards,

Edson Richter

  ----- Original Message ----- 
  From: McCaffrey, John G. 
  To: 'OJB Users List' 
  Sent: Thursday, March 18, 2004 4:33 PM
  Subject: 1 to 1 mapping


  I am trying to join two tables A and B
  table A has three primary keys
  Main_ID
  Node_ID
  Process_Date

  table B has two primary keys
  Node_ID
  Process_Date

  my mapping has the Table A object containing a collection of B obj
  I want to join the collection using the Node_ID, because it is the only
  thing they can be joined on

  when I do the mapping

  <collection-descriptor name="aObj" element-class-ref="x.x.x.AObj"
  proxy="false" auto-retrieve="true" > 
  <inverse-foreignkey field-ref="node_ID"/>
  </collection-descriptor>

  it complains about an arrayIndexOutOfBounds 
  but it works when the only primary key is Node_ID 

  i don't get it


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  For additional commands, e-mail: ojb-user-help@db.apache.org



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