Is there a way to include files automatically based on directory structure?
I do not want to add each and every file name with file Id tab.
My build process create the required directory structure:
ProductName
Directory1
Directory2
Directory3
Directory4
How can I add those directories and their subdirectories?
No, not automatically. There are some tools however (called "tallow" for Wix" or "heat" for Wix3) that will scan a directory and create a Wix fragment (a separate WiX *.wxs file) for you. You can then compile that "filelist.wxs" file (or whatever you call it) into your WiX install.
See this page for the WiX3 heat documentation and there should also be a WiX2 equivalent for tallow on that site.
Marc