Defining rota app class models

Defining the classes for the rota app model. This corresponds to the
relationships that we're creating between Rota's users, and
intermediate store for capturing whether a user has said yes/no/maybe.

Should make sense from looking at the code and the respective comments.

Author: rdobson

control/rotarise/rotas/models.py

@@ -1,3 +1,40 @@
 from django.db import models
+from django.contrib.auth.models import User
 
 # Create your models here.
+
+
+class Rota(models.Model):
+    """Class for each invdividual 'rota'. This is assumed to
+    consist of a purpose .e.g. music group, and have associated with it
+    a number of slots for which members of the rota are asked to 
+    signup to."""
+
+    label = models.CharField(max_length=30)
+    description = models.TextField(max_length=500)
+    owners = models.ManyToManyField(User, related_name='owner_set')
+    users = models.ManyToManyField(User, related_name='user_set')
+
+class RotaSlot(models.Model):
+    """A particular labeled slot for a chosen day. This must
+    be associated with a particular rota."""
+    
+    rota = models.ForeignKey(Rota)
+    label = models.CharField(max_length=30)
+    date = models.DateField()
+
+
+class UserSlotAssoc(models.Model):
+    """The data structure used to link together users and a particular
+    rota slot as there may well be more than one person signing up for a particular
+    rota slot."""
+
+    user = models.ForeignKey(User)
+    rota_slot = models.ForeignKey(RotaSlot)
+
+    # 0 = No, 1 = yes, 2 = maybe
+    option = models.SmallIntegerField()
+    
+    # Indicating whether the user has been 'selected' for this slot, and
+    # so composed on any lists that are produced for this slot.
+    selected = models.BooleanField()