I removed the media database in an earlier commit, but it's now necessary
again as I decided to add native media syncing to AnkiWeb.
This time, the DB is stored in the media folder rather than with the deck.
This means we avoid sending it in a full sync, and makes deck backups faster.
The DB is a cache of file modtimes and checksums. When findChanges() is
called, the code checks to see which files were added, changed or deleted
since the last time, and updates the log of changes. Because the scanning step
and log retrieval is separate, it's possible to do the scanning in the
background if the need arises.
If the DB is deleted by the user, Anki will forget any deletions, and add all
the files back to the DB the next time it's accessed.
File changes are recorded as a delete + add.
media.addFile() could be optimized in the future to log media added manually
by the user, allowing us to skip the full directory scan in cases where the
only changes were manually added media.
Like the previous change, models have been moved from a separate DB table to
an entry in the deck. We need them for many operations including reviewing,
and it's easier to keep them in memory than half on disk with a cache that
gets cleared every time we .reset(). This means they are easily serialized as
well - previously they were part Python and part JSON, which made access
confusing.
Because the data is all pulled from JSON now, the instance methods have been
moved to the model registry. Eg:
model.addField(...) -> deck.models.addField(model, ...).
- IDs are now timestamped as with groups et al.
- The data field for plugins was also removed. Config info can be added to
deck.conf; larger data should be stored externally.
- Upgrading needs to be updated for the new model structure.
- HexifyID() now accepts strings as well, as our IDs get converted to strings
in the serialization process.
