- Add `LyricsMetadataInFlexFieldsMigration` to extract legacy source
URLs and language metadata from lyrics text into flex attributes
- Add `Lyrics.from_legacy_text` to parse legacy lyrics format
- Move `with_row_factory` context manager up to base `Migration` class
- Rename `migrate_table` to `migrate_model` and pass model class
instead of table name string. This is so that the migration can access
both `_table` and `_flex_table` attributes.
- Make `langdetect` import optional in `Lyrics.__post_init__`: users may
not have have the dependency installed, and we do not want the
migration to fail because of that.
- Move `BACKEND_BY_NAME` to module level for use outside plugin class
* Move genre-to-genres migration into a dedicated Migration class and
wire it into Library._migrations for items and albums.
* Add batched SQL updates via mutate_many and share the multi-value
delimiter as a constant.
* Cover migration behavior with new tests.
I initially attempted to migrate using our model infrastructure
/ Model.store(), see the comparison below:
Durations migrating my library of ~9000 items and ~2300 albums:
1. Using our Python logic: 11 minutes
2. Using SQL directly: 4 seconds
That's why I've gone ahead with option 2.
