how we generate report in excel format
It will help to understand the use case if you provide additional details on what you are looking for. Maybe provide some references to subclasses you have, which attributes are configured on what subclasses, how the objects of the subclasses are related and what you are looking for in your search results.
if you are trying to create a report that includes some summary in Excel but also include a single file with PDF versions of ALL the drawings uploaded to A9, you will have to write a long and complex PX code to do that for you.
I’ve done it and it works, but It’s better to pay for a commercial library file conversion tool than using open source version of various toosl.