Refactor

Moves from_json to utils and splits the models to files in a module

playlist/models/track.py

@@ -0,0 +1,32 @@
+from django.db import models
+from .album import Album
+from .artist import Artist
+from .utils import from_json
+
+class TrackManager(models.Manager):
+    def get_queryset(self):
+        return super().get_queryset().filter(old=False)
+
+class Track(models.Model):
+    def __str__(self):
+        s = f"'{self.name}'"
+        if self.artists.count() > 0:
+            artists = list(map(lambda a:a.name, self.artists.all()))
+            s += " by "
+            s += " & ".join(artists)
+        return s
+    id = models.CharField(primary_key=True, max_length=128)
+    name = models.CharField(max_length=255)
+    artists = models.ManyToManyField(Artist)
+    album = models.ForeignKey(Album, null=True, on_delete=models.SET_NULL)
+
+    explicit = models.BooleanField(default=False)
+    duration_ms = models.PositiveIntegerField(null=True)
+    popularity = models.PositiveIntegerField(null=True)
+
+    banter = models.TextField(blank=True)
+
+    old = models.BooleanField(default=False)
+
+    objects = TrackManager()
+    all_tracks = models.Manager()