Situation:
You're trying to create a Report Book. You have the book report created, and now trying to pull in the reports for the book itself. Studio tells you that you need a .jasper file. How to create or where to get that? The reports that you want to include already exist, were created with Studio, and are published to the server.
Solution:
The .jasper file is a compiled version of jrxml file. To get a jasper file, open the report in studio and press Compile Report button which is to the left of Dataset and Query button. This will generate the .jasper file in your workspace and you can point to it in the book.
You can right click at content in outline, press Add new book part, press Select a report file, use Workspace, press Browse and just point it to a JRXML. It'll put .jasper in the expression, that jasper file will be generated when you preview the book.
When uploading a book though, studio will upload the JRXML files as book resources. If you want to use reports from the server as parts of the book, you'll need to upload them as JRXML files and not as report units.
