added schedule models (not fully complete)

symposion/schedule/models.py

@@ -0,0 +1,59 @@
+from django.db import models
+
+from symposion.conference.models import Section
+
+
+class Schedule(models.Model):
+    
+    section = models.OneToOneField(Section)
+
+
+class Day(models.Model):
+    
+    date = models.DateField()
+
+
+class Track(models.Model):
+    
+    name = models.CharField(max_length=65)
+    room = models.CharField(max_length=100)
+
+
+class Slot(models.Model):
+    
+    day = models.ForeignKey(Day)
+    track_set = models.TextField(db_column="tracks")
+    start = models.TimeField()
+    end = models.TimeField()
+    
+    @property
+    def tracks(self):
+        attr = "_tracks"
+        if not hasattr(self, attr):
+            slot = self
+            class TrackSet(object):
+                
+                def __init__(self, data, delimiter):
+                    self.data = set(data.split(delimiter))
+                
+                def __iter__(self):
+                    return Track.objects.filter(pk__in=self.data)
+                
+                def add(self, track, commit=True):
+                    """
+                    Add given track to the set, but check if it can exist
+                    before adding it.
+                    """
+                    self.data.add(track.pk)
+                    self._update_model(commit=commit)
+                
+                def remove(self, track, commit=True):
+                    self.data.remove(track.pk)
+                    self._update_model(commit=commit)
+                
+                def _update_model(self, commit=True):
+                    slot.track_set += self.delimiter.join(self.data)
+                    if commit:
+                        slot.save(force_update=True)
+            setattr(self, attr, TrackSet(self.track_set, delimiter=" "))
+        return getattr(self, attr)