customized datasource to generate report using visualization template in webcenter portal 12 c

Our requirement is to generate reports at runtime in webcenter portal 12 c.We have a Dashboard page to generate report where forms will be populated as a dropdown.

End user will select a particular form to generate the report using built in visualization templates. But in webcenter portal as an end user always have to create

datasource (SQL or Rest).where they have to write the sql statement.Therefore end user cannot edit datasource each and every time to generate report.

Can I generate report using visualization template without using OOTB datasorce?

like as a developer we will provide one interface to user where they can