DictModel

dictmodel.py

from google.appengine.ext import db
import datetime
import time

SIMPLE_TYPES = (int, long, float, bool, dict, basestring, list)
# taken from http://stackoverflow.com/questions/1531501/json-serialization-of-google-app-engine-models/1532035#1532035
class DictModel(db.Model):
    def to_dict(self):
        output = {}

        for key, prop in self.properties().iteritems():
            value = getattr(self, key)

            if value is None or isinstance(value, SIMPLE_TYPES):
                output[key] = value
            elif isinstance(value, datetime.date):
                # Convert date/datetime to ms-since-epoch ("new Date()").
                ms = time.mktime(value.utctimetuple()) * 1000
                ms += getattr(value, 'microseconds', 0) / 1000
                output[key] = int(ms)
            elif isinstance(value, db.GeoPt):
                output[key] = {'lat': value.lat, 'lon': value.lon}
            elif isinstance(value, db.Model):
                output[key] = value.to_dict()
            else:
                raise ValueError('cannot encode ' + repr(prop))

        return output