iBatis resultMap groupBy Question

[aditee sharma]

Hi,
Given parent table : ORDER_ITEMS
related to child table : ITEM_SHIPMENT by two keys ORDER_ID and ORDER_LINE_ID (both the keys are required to establish a precise parent-child relation)
if we want to get a list of child table a store in a parent object in iBatis, we do :
<resultMap id="parent" class="Parent" groupBy="parentId">

But in this case, we have 2 keys, so I do not know how to do it.
Can groupBy be mapped to another class that can have both these keys as members ?

[aditee sharma]

correction :
......
if we want to fetch child records and store in parent object
.....

[aditee sharma]

is ther no body who has faced this situation ?
How do we put a composite key in groupBy of Ibatis resultMap

[Dhananjay Patkar]

Hi aditee,
It seems you are facing N+1 problem in iBatis...Which is fully solvable
Below code snipet will solve your problem
This is from iBatis Developer guide

 <sqlMap namespace="ProductCategory">
<resultMap id=�categoryResult� class=�com.ibatis.example.Category� groupBy=�id�>
<result property=�id� column=�CAT_ID�/>
<result property=�description� column=�CAT_DESCRIPTION�/>
<result property=�productList� resultMap=�ProductCategory.productResult�/>
</resultMap>
<resultMap id=�productResult� class=�com.ibatis.example.Product�>
<result property=�id� column=�PRD_ID�/>
<result property=�description� column=�PRD_DESCRIPTION�/>
</resultMap>
<select id=�getCategory� parameterClass=�int� resultMap=�categoryResult�>
select C.CAT_ID, C.CAT_DESCRIPTION, P.PRD_ID, P.PRD_DESCRIPTION
from CATEGORY C
left outer join PRODUCT P
on C.CAT_ID = P.PRD_CAT_ID
where CAT_ID = #value#
</select>
</sqlMap>
 
//When you call...
List myList = queryForList("ProductCategory.getCategory", new Integer(1002));   

myList is a List of beans containing type
"com.ibatis.example.Category". Each object in that List will have a "productList" property that is also a List
populated from the same query, but using the "productResult" result map to populate the beans in the child
list. So, you end up with a list containing sub-lists, and only one database query is executed and both child and parent list are get popultaed as expected..

Cheers,
Dhananjay