A second base class, LibModel, maintains a reference to the Library and should
take care of database-related tasks like load and store. This is the beginning
of the end of the terrible incongruity between Item and Album objects (only
the latter had a library reference). More refactoring to come.
One large side effect: Album objects no longer automatically store
modifications. You have to call album.store(). Several places in the code
assume otherwise; they need cleaning up.
ResultIterator is now polymorphic (it takes a type parameter, which must be a
subclass of LibModel).
In preparation for enabling queries over flexattrs, this is a new path that
lets queries avoid generating SQLite expressions altogether. Any query that
can be completely evaluated in SQLite will be, but when it can't, we now fall
back to running the entire query in Python by selecting everything from the
database and running the `match` predicate.
To begin with, this mechanism replaces RegisteredFieldQueries, which
previously used Python callbacks for evaluation. Now they just indicate that
they're slow queries and the query system falls back automatically.
This has the great upside that it lets use implement arbitrarily complex
queries without shoehorning everything into SQLite when that (a) is way too
complicated and (b) doesn't buy us much performance anyway. The obvious
drawback is that any code dealing with queries now has to handle two cases
(slow and fast).
In the future, we could optimize this further by combing fast and slow query
styles. For example, if you want to match with a substring *and* a regular
expression, we can do a first pass in SQLite and apply the regex predicate on
the results. Avoided for now because premature optimization, etc., etc.
Next step: implement flexattr matches as slow queries.
bs4 scraping routine has been made more generic,
relying less on specific markup tags.
Better algorithm to detect which url titles match
song titles: domain names are now removed from url
titles.
Use regex to decimate \n in fetched lyrics.
This also brought to light the fact that the distance calculations for tracks
was incorrect because there's no source field on TrackInfo objects yet. This
needs to be fixed.
The new Distance object knows how to perform various types of distance
calculations (expression, equality, number, priority, string).
It will keep track of each individual penalty that has been applied so
that we can utilise that information in the UI and when making decisions
about the recommendation level.
We now display the top 3 penalties (sorted by weight) on the release
list (and "..." if there are more than 3), and we display all penalties
on the album info line and track change line.
The implementation of the `max_rec` setting has been simplified by
removing duplicate validation and instead looking at the penalties that
have been applied to a distance. As a result, we can now configure a
maximum recommendation for any penalty that might be applied.
We have a few new checks when calculating album distance:
`match: preferred: countries` and `match: preferred: media` can each be
set to a list of countries and media in order of your preference. These
are empty by default. A value that matches the first item will have no
penalty, and a value that doesn't match any item will have an unweighted
penalty of 1.0.
If `match: preferred: original_year` is set to "yes", beets will apply
an unweighted penalty of 1.0 for each year of difference between the
release year and the original year.
We now configure individual weights for `mediums` (disctotal), `label`,
`catalognum`, `country` and `albumdisambig` instead of a single generic
`minor` weight. This gives more control, but more importantly separates
and names the applied penalties so that the UI can convey exactly which
fields have contributed to the overall distance penalty.
Likewise, `missing tracks` and `unmatched tracks` are penalised and
displayed in the UI separately, instead of a combined `partial` penalty.
Display non-MusicBrainz source in the disambiguation string, and
"source" in the list of penalties if a release is penalised for being
a non-MusicBrainz.
As outlined in #299, we broke many places in the code that were expecting
_album_for_id and _track_for_id to return a single item rather than a list. I
took this opportunity to divide up the interface: there's now one function for
MBIDs (returning a single object or None) and one for generic IDs (returning a
list).
It's possible that these plugins might require a little more thought
into how they should work (or not work) with potentially multiple albums
matching an idea, and potentially those those albums being an incorrect
match (e.g. if two data source plugins share a simple numerical ID
format).
