Multi-Record-Selection DSRequest: How to add additional data to whole request ?

[SchlauKunde]

The scenario is as follows:
- Hierarchical ListGrid
- Having a multi-row selection in an embedded ListGrid
- Operation to execute: Delete the underlying records of the multi-row selection
- In order to successfully execute the delete operation, I need two primary keys in the request:
- One identifying a record underlying a selected row: Is automatically contained in the request by using the selection
- One identifying the parent record of the selected rows: I have to add this key manually to the request somehow ... On the level of the whole request; there is no need to add the same parent key to each sub-DSRequest the whole request may contain


Here comes my current code approach - using the 'params' attribute of a client-side DSRequest:

- On the client-side:

In 'getExpansionComponent: function (record, rowNum, colNum) {':

embeddedGrid.removeSelectedData(null,({params:{idParentRecord: record.idParentRecord}}))

- On the server-side:

In an operation binding for the remove operation:

$servletRequest.getParameter("idParentRecord")


But unfortunately, the Velocity expression on the server-side does not seem to evaluate to the needed value I wanted to transfer to the server-side additionally ... I have tried other syntaxes, too; but so far without success ...

Could someone please shed some light on this important, ever-and-ever again occurring topic ?