Python – ImportError: No module named django.utils

When I follow the tutorial – App Engine Series #4 – I got this error for Ajax.py:

ImportError: No module named django.utils

According to this article, Python 2.7 uses native JSON library.

Fixed source for Ajax.py is this:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Including the models:
from models.models import *

# from Phyton 2.7, use native JSON library
import json

from datetime import datetime,timedelta
from google.appengine.ext import webapp, db
from google.appengine.api import memcache

# The AJAX controllers:

class TwentyFourHours(webapp.RequestHandler):
    def get(self):

        # This class selects the response times
        # for the last 24 hours.

        # Checking whether the result of this
        # function is already cached in memcache:
        jsonStr = memcache.get("TwentyFourHoursCache")

        # If it is not, we need to generate it:
        if jsonStr is None:

            query = db.GqlQuery("SELECT * FROM Ping WHERE date>:dt ORDER BY date",
                        dt=(datetime.now() - timedelta(hours = 24)))

            results = query.fetch(limit=300)
            chart = []
            for Ping in results:
                chart.append({
                    "label": Ping.date.strftime("%H:%M"),
                    "value": Ping.responseTime
                })

            jsonStr = json.dumps({
                "chart"        : {
                    # tooltip is used by the jQuery chart:
                    "tooltip"    : "Response time at %1: %2ms",
                    "data"        : chart
                },
                "downtime"    : getDowntime(1)
            })

            # Caching it for five minutes:
            memcache.add("TwentyFourHoursCache", jsonStr, 300)

        self.response.out.write(jsonStr);

class SevenDays(webapp.RequestHandler):
    days = 7
    def get(self):

        # Selecting the response times for the last seven days:
        query = db.GqlQuery("SELECT * FROM Day WHERE date>:dt ORDER BY date",
                dt=(datetime.now() - timedelta(days = self.days)))

        results = query.fetch(limit=self.days)
        chart = []
        for Day in results:
            chart.append({
                "label": Day.date.strftime("%b, %d"),
                "value": Day.averageResponseTime
            })

        self.response.out.write(json.dumps({
            "chart"        : {
                "tooltip"    : "Average response time for %1: %2ms",
                "data"        : chart
            },
            "downtime"    : getDowntime(self.days)
        }))

# Extending the SevenDays class and only
# increasing the days member:

class ThirtyDays(SevenDays):
    days = 30

def getDowntime(days=1):

    # Checking whether the result of this function
    # already exists in memcache. Notice the key for get():

    downTimeList = memcache.get("DownTimeCache"+str(days))
    if downTimeList is None:

        query = db.GqlQuery("SELECT * FROM DownTime WHERE date>:dt ORDER BY date",
                dt=(datetime.now() - timedelta(days = days)))

        results = query.fetch(limit=100)

        downTimeList = []
        downTimePeriod = {}

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

        # This loop "compacts" the downtime:

        for DownTime in results:

            if not downTimePeriod.has_key("begin"):
                downTimePeriod = {"begin":DownTime.date,"end":DownTime.date}
                continue

            if DownTime.date - downTimePeriod['end'] < timedelta(minutes=8):                 downTimePeriod['end'] = DownTime.date             else:                 downTimeList.append(downTimePeriod)                 downTimePeriod = {"begin":DownTime.date,"end":DownTime.date}         downTimeList.append(downTimePeriod)         # Formatting the output of this function:         for i in downTimeList:             if i['end'] + timedelta(minutes=5) > datetime.now():
                i['period'] = timedeltaFormat(((datetime.now() - i['begin'])).seconds)
                i['end'] = "NOW"
            else:
                i['period'] = timedeltaFormat(((i['end'] - i['begin']) + timedelta(minutes=5)).seconds)
                i['end'] = (i['end']+timedelta(minutes=5)).strftime('%H:%M on %b, %d, %Y')    

            i['begin'] = i['begin'].strftime('%H:%M on %b, %d, %Y')

        # Storing the response in memcache:
        memcache.add("DownTimeCache"+str(days), downTimeList, 300)

    return downTimeList

# A helper function for formatting time periods.

def timedeltaFormat(seconds):
    hours, remainder = divmod(seconds, 3600)
    minutes, seconds = divmod(remainder, 60)

    return ('%02d:%02d:%02d' % (hours, minutes, seconds))