Add ticket_type property to Attendee

This vastly simplifies templates and many many things which need to
look this up.

vendor/registrasion/registrasion/models/people.py

@@ -1,11 +1,13 @@
 from registrasion import util
 
+from django.conf import settings
 from django.contrib.auth.models import User
 from django.core.exceptions import ObjectDoesNotExist
 from django.db import models
 from django.utils.encoding import python_2_unicode_compatible
 from model_utils.managers import InheritanceManager
 
+from registrasion.models.commerce import Invoice, ProductItem
 
 # User models
 
@@ -45,6 +47,19 @@ class Attendee(models.Model):
     completed_registration = models.BooleanField(default=False)
     guided_categories_complete = models.ManyToManyField("category", blank=True)
 
+    @property
+    def ticket_type(self):
+        tickets = ProductItem.objects.select_related(
+            "product","product__category","cart",
+        )
+        tickets = tickets.filter(
+            product__category=settings.TICKET_PRODUCT_CATEGORY,
+            cart__invoice__status=Invoice.STATUS_PAID,
+            cart__invoice__user=self.user
+        )
+        if len(tickets) >1:
+            raise ValueError("Too many tickets for attendee %s", self)
+        return tickets[0].product.name
 
 class AttendeeProfileBase(models.Model):
     ''' Information for an attendee's badge and related preferences.