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iBatis resultMap groupBy Question

aditee sharma
Ranch Hand

Joined: Jul 22, 2008
Posts: 182
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
Ranch Hand

Joined: Jul 22, 2008
Posts: 182
correction :
......
if we want to fetch child records and store in parent object
.....
aditee sharma
Ranch Hand

Joined: Jul 22, 2008
Posts: 182
is ther no body who has faced this situation ?
How do we put a composite key in groupBy of Ibatis resultMap
Dhananjay Patkar
Greenhorn

Joined: Aug 12, 2008
Posts: 8
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



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
 
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subject: iBatis resultMap groupBy Question