The WD_CONTEXT attribute is a reference to the root node of the controller context. Regardless of the edited controller, it is always a reference variable of type IF_WD_CONTEXT_NODE. You can use WD_CONTEXT and the interface methods to edit the content of a context node in your controller method.
The controller context contains the MY_TABLE_NODE node. You can use the INVALIDATE_TABLE_NODE method to invalidate the values of the node elements.
method INVALIDATE_TABLE_NODE . data: TABLE_NODE type ref to IF_WD_CONTEXT_NODE. TABLE_NODE = WD_CONTEXT->GET_CHILD_NODE( 'MY_TABLE_NODE' ). TABLE_NODE->INVALIDATE( ). endmethod.
GET_CHILD_NODE and INVALIDATE are methods of the IF_WD_CONTEXT_NODE interface. Other frequently used methods are GET_ATTRIBUTE or BIND_ELEMENT, for example. For a complete list of methods and their functions, refer to the reference section of this documentation (link is above).