This is another one of my experiments.
I prefer folder navigation over anything else really, but the Kobo doesn't have it. It only offers shelves/collections. So I wrote a script that creates a shelf for each folder, and puts everything in that folder onto the shelf. (I know Calibre has a feature to do this, but I don't use Calibre for putting books on the reader.)
These shelves are updated whenever the reader leaves the "connected and charged" screen after unplugging the USB cable, and only if there was a change in your list of books since the previous update. Building the list of shelves takes a few minutes if you have lots of files. There is no visual feedback when it's done. Unfortunately for internal reasons I've yet to overcome, the shelves are not displayed instantly but require yet another plug-connect-unplug cycle (or alternatively a reboot).
Any shelf created by this addon will end with /. So books in the root directory will be in the '/' shelf, and then there's a 'Harry Potter/' shelf - if you have a subdir for that series. Since there is no shelf-within-shelf feature (or is there?), shelves for deeper structures will end up as 'some/other/shelf/', so you get a flattened view of all subdirs.
It also sets the Series and SeriesNumber properties of books, but it only works if the number is the first element of your filename (like 'Harry Potter/001 Philosophers Stone.epub'). That way you can see the folder and series number anywhere in the book list. Otherwise it will show the filename.
Sorting within a shelf unfortunately does not work at all. I do not understand it. There are two sort options that relate to date (recent and date added). But no matter what dates I set in the database, it does not seem to affect sorting. I even tried setting file timestamps, to no avail. Either there's a date field I'm missing, or I'm setting them wrong, or the firmware is buggy and does something else when it claims to be date sorting.
Note there is a chance this will corrupt your database. Make backups of your .kobo/KoboReader.sqlite.
Edit: beta2 released
I prefer folder navigation over anything else really, but the Kobo doesn't have it. It only offers shelves/collections. So I wrote a script that creates a shelf for each folder, and puts everything in that folder onto the shelf. (I know Calibre has a feature to do this, but I don't use Calibre for putting books on the reader.)
These shelves are updated whenever the reader leaves the "connected and charged" screen after unplugging the USB cable, and only if there was a change in your list of books since the previous update. Building the list of shelves takes a few minutes if you have lots of files. There is no visual feedback when it's done. Unfortunately for internal reasons I've yet to overcome, the shelves are not displayed instantly but require yet another plug-connect-unplug cycle (or alternatively a reboot).
Any shelf created by this addon will end with /. So books in the root directory will be in the '/' shelf, and then there's a 'Harry Potter/' shelf - if you have a subdir for that series. Since there is no shelf-within-shelf feature (or is there?), shelves for deeper structures will end up as 'some/other/shelf/', so you get a flattened view of all subdirs.
It also sets the Series and SeriesNumber properties of books, but it only works if the number is the first element of your filename (like 'Harry Potter/001 Philosophers Stone.epub'). That way you can see the folder and series number anywhere in the book list. Otherwise it will show the filename.
Sorting within a shelf unfortunately does not work at all. I do not understand it. There are two sort options that relate to date (recent and date added). But no matter what dates I set in the database, it does not seem to affect sorting. I even tried setting file timestamps, to no avail. Either there's a date field I'm missing, or I'm setting them wrong, or the firmware is buggy and does something else when it claims to be date sorting.
Note there is a chance this will corrupt your database. Make backups of your .kobo/KoboReader.sqlite.
Edit: beta2 released