Register mopidy models for deserialization.

All from ValidatedImmutableObject derived classes are registered
for automatically deserialization by model_json_decoder().

mopidy/internal/models.py

@@ -4,9 +4,6 @@ from mopidy.internal import validation
 from mopidy.models import Ref, TlTrack, fields
 from mopidy.models.immutable import ValidatedImmutableObject
 
-_MODELS = ['HistoryTrack', 'HistoryState', 'MixerState', 'PlaybackState',
-           'TracklistState', 'CoreState']
-
 
 class HistoryTrack(ValidatedImmutableObject):
     """

mopidy/models/immutable.py

@@ -8,6 +8,10 @@ from mopidy.internal import deprecation
 from mopidy.models.fields import Field
 
 
+# Registered models for automatic deserialization
+_models = {}
+
+
 class ImmutableObject(object):
     """
     Superclass for immutable objects whose fields can only be modified via the
@@ -150,9 +154,14 @@ class _ValidatedImmutableObjectMeta(type):
         attrs['_instances'] = weakref.WeakValueDictionary()
         attrs['__slots__'] = list(attrs.get('__slots__', [])) + fields.values()
 
-        return super(_ValidatedImmutableObjectMeta, cls).__new__(
+        clsc = super(_ValidatedImmutableObjectMeta, cls).__new__(
             cls, name, bases, attrs)
 
+        if clsc.__name__ != 'ValidatedImmutableObject':
+            _models[clsc.__name__] = clsc
+
+        return clsc
+
     def __call__(cls, *args, **kwargs):  # noqa: N805
         instance = super(_ValidatedImmutableObjectMeta, cls).__call__(
             *args, **kwargs)

mopidy/models/serialize.py

@@ -4,8 +4,6 @@ import json
 
 from mopidy.models import immutable
 
-_MODELS = ['Ref', 'Artist', 'Album', 'Track', 'TlTrack', 'Playlist']
-
 
 class ModelJSONEncoder(json.JSONEncoder):
 
@@ -40,11 +38,8 @@ def model_json_decoder(dct):
 
     """
     if '__model__' in dct:
-        from mopidy import models
         model_name = dct.pop('__model__')
-        if model_name in _MODELS:
-            return getattr(models, model_name)(**dct)
-        from mopidy import internal
-        if model_name in internal.models._MODELS:
-            return getattr(internal.models, model_name)(**dct)
+        if model_name in immutable._models:
+            cls = immutable._models[model_name]
+            return cls(**dct)
     return dct