gistfile1.js

var renderChildTable = function(parentId) {

    GRAILSUI.childTable.customQueryString = 'id=' + myParentId;

    var newState = {
        startIndex: 0,
        sorting: { // Sort values
            key: 'id', // or whatever you want the default sort on
            dir: YAHOO.widget.DataTable.CLASS_ASC
        },
        pagination : { // Pagination values
            recordOffset: 0, // Default to first page when sorting
            rowsPerPage: GRAILSUI.childTable.get("paginator").getRowsPerPage()
        }
    };

    // Create callback object for the request
    var oCallback = {
        success: this.onDataReturnSetRows,
        failure: this.onDataReturnSetRows,
        scope: this,
        argument: newState // Pass in new state as data payload for callback function to use
    };

    // Send the request
    GRAILSUI.childTable.getDataSource().sendRequest(GRAILSUI.childTable.buildQueryString(newState), oCallback);


};

GRAILSUI.parentTable.subscribe('rowClickEvent', function(e) {
    var selectedRows = this.getSelectedRows();
    var parentId = this.getRecord(selectedRows[0]).getData().id;
    renderChildTable(parentId);
});