gistfile1.txt

from django.db import models
from django.utils.translation import ugettext as _
from colleges.models import College


WEEKDAYS = [
  (1, _(u'Monday')),
  (2, _(u'Tuesday')),
  (3, _(u'Wednesday')),
  (4, _(u'Thursday')),
  (5, _(u'Friday')),
  (6, _(u'Saturday')),
  (7, _(u'Sunday')),
]


class Activity(models.Model):
    name = models.CharField(max_length=50, blank=False)
    latitude = models.FloatField(blank=True, null=True)
    longitude = models.FloatField(blank=True, null=True)
    website = models.URLField(blank=True)
    telephone = models.CharField(max_length=10, blank=True)
    description = models.CharField(max_length=500, blank=True)
    college = models.ForeignKey(College, blank=False)


class ActivityTime(models.Model):
    day = models.CharField(choices=WEEKDAYS, max_length=1, blank=False)
    open = models.TimeField(blank=False)
    close = models.TimeField(blank=False)
    activity = models.ForeignKey(Activity, blank=False)

gistfile2.txt

from activities_services.models import Activity
from activities_services.models import ActivityTime
from activities_services.models import WEEKDAYS
from rest_framework import serializers


class ActivityTimeSerializer(serializers.ModelSerializer):
    class Meta:
        model = ActivityTime


class ActivitySerializer(serializers.ModelSerializer):
    hours = serializers.SerializerMethodField()

    class Meta:
        model = Activity

    def get_hours(self, obj):
        matches = ActivityTime.objects.filter(activity=obj)

        if len(matches) == 0:
            return []

        if len(matches) == 1:
            serializer = ActivityTimeSerializer(matches)
        else:
            serializer = ActivityTimeSerializer(matches, many=True)
        return serializer.data

gistfile3.txt

Got AttributeError when attempting to get a value for field `day` on serializer `ActivityTimeSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `QuerySet` instance.
Original exception text was: 'QuerySet' object has no attribute 'day'.

You left IRC just before I replied:

Is hours supposed to contain all of the activitytime data, nested?
If so, you might want to try: http://www.django-rest-framework.org/api-guide/relations/#nested-relationships