models: Convert all models to using fields.

mopidy/models.py

@@ -128,12 +128,15 @@ class ImmutableObject(object):
 
     """
     Superclass for immutable objects whose fields can only be modified via the
-    constructor.
+    constructor. Fields should be :class:`Field` instances to ensure type
+    safety in our models.
 
     :param kwargs: kwargs to set as fields on the object
     :type kwargs: any
     """
 
+    __metaclass__ = FieldOwner
+
     def __init__(self, *args, **kwargs):
         for key, value in kwargs.items():
             if not hasattr(self, key) or callable(getattr(self, key)):
@@ -142,7 +145,7 @@ class ImmutableObject(object):
                     key)
             if value == getattr(self, key):
                 continue  # Don't explicitly set default values
-            self.__dict__[key] = value
+            super(ImmutableObject, self).__setattr__(key, value)
 
     def __setattr__(self, name, value):
         if name.startswith('_'):
@@ -192,7 +195,7 @@ class ImmutableObject(object):
         :type values: dict
         :rtype: new instance of the model being copied
         """
-        data = {}
+        data = {}  # TODO: do we need public key handling now?
         for key in self.__dict__.keys():
             public_key = key.lstrip('_')
             value = values.pop(public_key, self.__dict__[key])
@@ -207,7 +210,7 @@ class ImmutableObject(object):
         return self.__class__(**data)
 
     def serialize(self):
-        data = {}
+        data = {}  # TODO: do we need public key handling now?
         data['__model__'] = self.__class__.__name__
         for key in self.__dict__.keys():
             public_key = key.lstrip('_')
@@ -282,14 +285,10 @@ class Ref(ImmutableObject):
     """
 
     #: The object URI. Read-only.
-    uri = None
+    uri = String()
 
     #: The object name. Read-only.
-    name = None
+    name = String()
-
-    #: The object type, e.g. "artist", "album", "track", "playlist",
-    #: "directory". Read-only.
-    type = None
 
     #: Constant used for comparison with the :attr:`type` field.
     ALBUM = 'album'
@@ -306,6 +305,10 @@ class Ref(ImmutableObject):
     #: Constant used for comparison with the :attr:`type` field.
     TRACK = 'track'
 
+    #: The object type, e.g. "artist", "album", "track", "playlist",
+    #: "directory". Read-only.
+    type = Field(choices=(ALBUM, ARTIST, DIRECTORY, PLAYLIST, TRACK))
+
     @classmethod
     def album(cls, **kwargs):
         """Create a :class:`Ref` with ``type`` :attr:`ALBUM`."""
@@ -346,13 +349,13 @@ class Image(ImmutableObject):
     """
 
     #: The image URI. Read-only.
-    uri = None
+    uri = String()
 
     #: Optional width of the image or :class:`None`. Read-only.
-    width = None
+    width = Integer(min=0)
 
     #: Optional height of the image or :class:`None`. Read-only.
-    height = None
+    height = Integer(min=0)
 
 
 class Artist(ImmutableObject):
@@ -367,13 +370,13 @@ class Artist(ImmutableObject):
     """
 
     #: The artist URI. Read-only.
-    uri = None
+    uri = String()
 
     #: The artist name. Read-only.
-    name = None
+    name = String()
 
     #: The MusicBrainz ID of the artist. Read-only.
-    musicbrainz_id = None
+    musicbrainz_id = String()
 
 
 class Album(ImmutableObject):
@@ -398,37 +401,32 @@ class Album(ImmutableObject):
     """
 
     #: The album URI. Read-only.
-    uri = None
+    uri = String()
 
     #: The album name. Read-only.
-    name = None
+    name = String()
 
     #: A set of album artists. Read-only.
-    artists = frozenset()
+    artists = Collection(type=Artist, container=frozenset)
 
     #: The number of tracks in the album. Read-only.
-    num_tracks = None
+    num_tracks = Integer(min=0)
 
     #: The number of discs in the album. Read-only.
-    num_discs = None
+    num_discs = Integer(min=0)
 
     #: The album release date. Read-only.
-    date = None
+    date = String()  # TODO: add date type
 
     #: The MusicBrainz ID of the album. Read-only.
-    musicbrainz_id = None
+    musicbrainz_id = String()
 
     #: The album image URIs. Read-only.
-    images = frozenset()
+    images = Collection(type=basestring, container=frozenset)
     # XXX If we want to keep the order of images we shouldn't use frozenset()
     # as it doesn't preserve order. I'm deferring this issue until we got
     # actual usage of this field with more than one image.
 
-    def __init__(self, *args, **kwargs):
-        self.__dict__['artists'] = frozenset(kwargs.pop('artists', None) or [])
-        self.__dict__['images'] = frozenset(kwargs.pop('images', None) or [])
-        super(Album, self).__init__(*args, **kwargs)
-
 
 class Track(ImmutableObject):
 
@@ -466,61 +464,52 @@ class Track(ImmutableObject):
     """
 
     #: The track URI. Read-only.
-    uri = None
+    uri = String()
 
     #: The track name. Read-only.
-    name = None
+    name = String()
 
     #: A set of track artists. Read-only.
-    artists = frozenset()
+    artists = Collection(type=Artist, container=frozenset)
 
     #: The track :class:`Album`. Read-only.
-    album = None
+    album = Field(type=Album)
 
     #: A set of track composers. Read-only.
-    composers = frozenset()
+    composers = Collection(type=Artist, container=frozenset)
 
     #: A set of track performers`. Read-only.
-    performers = frozenset()
+    performers = Collection(type=Artist, container=frozenset)
 
     #: The track genre. Read-only.
-    genre = None
+    genre = String()
 
     #: The track number in the album. Read-only.
-    track_no = None
+    track_no = Integer(min=0)
 
     #: The disc number in the album. Read-only.
-    disc_no = None
+    disc_no = Integer(min=0)
 
     #: The track release date. Read-only.
-    date = None
+    date = String()  # TODO: add date type
 
     #: The track length in milliseconds. Read-only.
-    length = None
+    length = Integer(min=0)
 
     #: The track's bitrate in kbit/s. Read-only.
-    bitrate = None
+    bitrate = Integer(min=0)
 
     #: The track comment. Read-only.
-    comment = None
+    comment = String()
 
     #: The MusicBrainz ID of the track. Read-only.
-    musicbrainz_id = None
+    musicbrainz_id = String()
 
     #: Integer representing when the track was last modified. Exact meaning
     #: depends on source of track. For local files this is the modification
     #: time in milliseconds since Unix epoch. For other backends it could be an
     #: equivalent timestamp or simply a version counter.
-    last_modified = None
+    last_modified = Integer(min=0)
-
-    def __init__(self, *args, **kwargs):
-        def get(key):
-            return frozenset(kwargs.pop(key, None) or [])
-
-        self.__dict__['artists'] = get('artists')
-        self.__dict__['composers'] = get('composers')
-        self.__dict__['performers'] = get('performers')
-        super(Track, self).__init__(*args, **kwargs)
 
 
 class TlTrack(ImmutableObject):
@@ -546,10 +535,10 @@ class TlTrack(ImmutableObject):
     """
 
     #: The tracklist ID. Read-only.
-    tlid = None
+    tlid = Integer(min=0)
 
     #: The track. Read-only.
-    track = None
+    track = Field(type=Track)
 
     def __init__(self, *args, **kwargs):
         if len(args) == 2 and len(kwargs) == 0:
@@ -577,23 +566,19 @@ class Playlist(ImmutableObject):
     """
 
     #: The playlist URI. Read-only.
-    uri = None
+    uri = String()
 
     #: The playlist name. Read-only.
-    name = None
+    name = String()
 
     #: The playlist's tracks. Read-only.
-    tracks = tuple()
+    tracks = Collection(type=Track, container=tuple)
 
     #: The playlist modification time in milliseconds since Unix epoch.
     #: Read-only.
     #:
     #: Integer, or :class:`None` if unknown.
-    last_modified = None
+    last_modified = Integer(min=0)
-
-    def __init__(self, *args, **kwargs):
-        self.__dict__['tracks'] = tuple(kwargs.pop('tracks', None) or [])
-        super(Playlist, self).__init__(*args, **kwargs)
 
     # TODO: def insert(self, pos, track): ... ?
 
@@ -617,19 +602,13 @@ class SearchResult(ImmutableObject):
     """
 
     # The search result URI. Read-only.
-    uri = None
+    uri = String()
 
     # The tracks matching the search query. Read-only.
-    tracks = tuple()
+    tracks = Collection(type=Track, container=tuple)
 
     # The artists matching the search query. Read-only.
-    artists = tuple()
+    artists = Collection(type=Artist, container=tuple)
 
     # The albums matching the search query. Read-only.
-    albums = tuple()
+    albums = Collection(type=Album, container=tuple)
-
-    def __init__(self, *args, **kwargs):
-        self.__dict__['tracks'] = tuple(kwargs.pop('tracks', None) or [])
-        self.__dict__['artists'] = tuple(kwargs.pop('artists', None) or [])
-        self.__dict__['albums'] = tuple(kwargs.pop('albums', None) or [])
-        super(SearchResult, self).__init__(*args, **kwargs)