Originally Posted by davidfor
If calibre can already do this for PDFs and RTFs when sending the books to devices...
Thanks for your ongoing interest davidfor
AFAIK Calibre doesn't update the XMP metadata in PDF's when it saves to disk, or sends to folder as a device; same goes for RTF. Kovid is not interested in changing Calibre in this regard ===>>> https://bugs.launchpad.net/calibre/+bug/1075794
And I'm not that interested in learning python, besides I wouldn't want to commit to contributing and maintaining Calibre plugins.
Remember I already have a working solution - via the use of a temporary library. All I wanted was to streamline that process by updating the books in situ. I wasn't looking to change how I update the PDF & RTF XMP metadata - that's working.
Using the idea from theducks
I can now create a text file with the paths to books of a given status ID, and using your Open With idea I can refresh the XMP in a single book. And if push comes to shove, I can use the temporary library solution.
If an Update XMP Metadata in PDF and RTF files
plugin happens to turn up then I'd be happy to test and use it.
My baseline requirement is integration of the metadata into file system search indexing. Apart from that I'm not sure why else you'd need the metadata as XMP in PDF or RTF files.