Descriptor 'date' requires a 'datetime

I am using piston to write a JSON api for an application I am writing which handles recurring calendar events.

My API was working for regular events, when I attempted to add logic to handle the recurrence, I started getting the following error:

descriptor 'date' requires a 'datetime.datetime' object but received a 'unicode'

Here is my handlers.py:

from piston.handler import BaseHandler
from lessons.models import NewEvent, EachEvent
import calendar
from datetime import datetime, timedelta

class CalendarHandler(BaseHandler):
allowed_methods = ('GET',)
model = EachEvent
fields = ('actualDate', ('manager', ('firstName', 'lastName')))

def next_date(startDate, recurrence, rangeStart):
    sd = startDate
    while (sd < rangeStart):
        print sd;
        sd += datetime.timedelta(recurrence)
    return sd

def read(self, request, uid, month, year):
    qs = NewEvent.objects.filter(manager__boss = request.user).filter(endDate__gte=datetime.date(year, month, 1)).filter(startDate__lte=datetime.date(year, month, calendar.mdays[month]))
    lessonList = []
    qsList = list(qs)
    for l in qsList:
        if l.frequency == 0:
            x = EachLesson()
            x.lessonID = l.id
            x.actualDate = l.startDate
            x.manager = l.manager
            lessonList.append(x)
        else:
            sd = next_date(l.startDate, l.frequency, datetime.date(year, month, 1))
            while (sd <= datetime.date(year, month, calendar.mdays[month])):
                x = EachLesson()
                x.lessonID = l.id
                x.actualDate = sd
                x.manager = l.manager
                lessonList.append(x)
                sd += datetime.timedelta(recurrence)

    return lessonList

frequency is an IntegerField, actualDate, startDate, and endDate are all DateField.

My URLconf accepts a uid, year, and month, all of which are passed as parameters to the CalendarHandler.read method.

By using from datetime import datetime, timedelta you have imported the datetime type from the datetime module. Thus when you call datetime.date you are calling a method on the datetime type.

I think what you want is to use the date type from the datetime module: