Recovering missiing taggs
 

Could have sworn I posted this earlier ...

Can anyone suggest an automated way to recover missing tags? I have tags in my actual ebooks, but a great many of these disappeared from the Calibre interface after a recent bout of fiddling. I really don't want to have to manually retrieve these tags!

Many thanks for any help.

If you have not 'updated' the book (conversion, polish....)
Caution
Edit Metadata: the book icon will read ALL metadata from within the book

You don't get to pick and choose, so be careful.

There is no bulk mode

@Hoods7070 By design the book files are themselves are not updated.

You might be able to get old values back from the existing format files if they've not been been through one of Embed, Polish or Modify. To test select a book and Single Edit Metadata, then select a format (eg EPUB) in the formats box, and click the blue circle 'i', if the old tags are restored, click Next, do next book - repeat until all books done. AFAIK the Set metadata from format selected feature is not available in Bulk Metadata Edit.

If you're on Windows 7 or 8 and the drive that holds the library is 'System Protected' then you might be able to use 'Restore Previous Versions' to recover an older version of the opf files and run the database restore.

But it would be a long and tedious task to do it via right clicking in Windows (File) Manager and I don't know how to do 'Restore Previous Versions' at the command line. There are 3rd party Command Line programs that do it for Windows Server (where 'Previous Versions' are referred to 'Shadow Copies'). I don't know if they work on Windows Desktop.

Bottom Line : before you engage in another 'bout of fiddling' backup your library, and make sure you understand how to restore from the backup.

BR

Thanks for that guys - @BetterRed's suggestion pointed out things I had never investigated before (the blue "i" next to formats) revealed some interesting stuff. Clearly my metadata are in a mess. Looks like a lot of tedious fixing ahead of me.