Metadata 'filters' on import
Thought I'd throw this idea out to the big brains on these boards.
I think it would be excellent if we could set up 'filters' when we ask calibre to batch-fetch metadata from multiple sources. By 'filters' I mean:
1) Enable / disable 'overwrite existing',
The idea is that if you have some metadata filled in for a certain group of books in a batch (ISBN, e.g., or Summary) it won't overwrite that data, but will fill in the blanks, as it were, from the first source that has those blanks filled...include or exclude 'covers' with this, and it could be a quick way to find those missing covers without overwriting your existing covers (I know, one can search for "cover:false", do a "Download covers only" and get the same thing, so that's less innovative...)
2) Enable / disable 'filter to existing tags'.
So often when I import metadata, it clutters up my nicely arranged tags list with tags that others like/use but I find irritating ('sf' for 'Science Fiction', for example) If this theoretical filter were enabled, it would only import and apply tags that match one of my existing tags. This could also be made case-sensitive or case-insensitive at the user's discretion, with a case-mixed match being converted to the case of the existing tag (e.g., science fiction -> Science Fiction). One could even expand the usefulness of this filter by allowing the user to add / edit 'plugboards' for tags that aren't in their taglist but are popular (e.g., 'sci-fi' -> 'Science Fiction', or even 'sf_adv' -> 'Science Fiction', 'Adventure'). It seems that kiwidude has come close to this with his Goodreads Metadata plugin, but as far as I can tell that uses a hard coded list instead of matching to the user's own taglist, and (i believe) only applies the filtering to tag imports from the one site...
I know not what I ask, not being conversant in the world of programming, I just think it could be useful from the user's point of view...and there seem to be an awful lot of smart beans on these here forums!