Customized search applicable to both normal datatable and datatable with child rows.

I have an application with two datatables.

1.Has only parent rows (no child rows) say datatable1.
2.Has parent rows as well as child rows say datatable2.

I want to implement only one search for both the datatables.

For the datatable2 I implemented davidkonrad's answer on this link: https://stackoverflow.com/questions/30471089/datatables-search-child-row-content/ which works fine.
But the search does not work for the datatable2.

Any help would be greatly appreciated.

Thank you.