Mapping - sum of line items

Hi Experts,

I am cutrrently working on File (CSV) --> Proxy , here iam looking for mapping logic to add data from multiple line items and create single target item. The line items are not in order. We need to keep adding the value based on validation rule.

Rule: IF Store No, Date, and TRNo are same then add the amount and map it to target amount (Sales amount) else pass the amount to
Sales amount.

Source File (CSV File) --> Proxy

8001,20120305, 79046, 98.00

8001, 20120305, 79048,170.10

8023,20120305, 130572, 81.67

8023,20120305, 130572, 145.83

Source Structure:

MT_Details

Store No

Date

TRNo

Amount

Target Structure:

MT_Target

Store_ID

Date

Tr.No

SalesAmount

Thanks in advance.

Best Regards,

Chandu