getDataKeyValue for Parent Grid

[Doug]

In JavaScript, if I have a handler for the double click event of a row (for example), and that event fires on a row in a detail table, how would I access the client data key of the parent row?  So something like this:

function RowDoubleClick(sender, eventArgs) {
    var tableName = eventArgs.get_tableView().get_name();
    if (tableName == "Master") {
        var masterRowId = eventArgs.getDataKeyValue("Id");
    }
    else {
        var detailRowId = eventArgs.getDataKeyValue("Id");
        var parentRowId = // This needs to be the key associated with the detail table from the parent table.
    }
}

[Doug]

Just for reference; I managed to achieve this using the following code:

function SearchGridRowDoubleClick(sender, eventArgs) {

    var tableName = eventArgs.get_tableView().get_name();

    if (tableName == "Master")
    {
        var jobId = eventArgs.getDataKeyValue("Id");

        // Snipped for brevity.
    }
    else
    {
        var parentRow = eventArgs.get_tableView().get_parentRow();
        var jobId = sender.get_masterTableView().get_dataItems()[parentRow.rowIndex - 1].getDataKeyValue("Id");

        // Snipped for brevity.
    }
}