Question

I am using GAE datastore with python and I want to count and display the number of records between two recent dates. for examples, how many records exist with a time signature between two minutes ago and three minutes ago in the datastore.
Thank you.

#!/usr/bin/env python

import wsgiref.handlers
from google.appengine.ext import db
from google.appengine.ext import webapp
from google.appengine.ext.webapp import template
from datetime import datetime

class Voice(db.Model):
    when = db.DateTimeProperty(auto_now_add=True)


class MyHandler(webapp.RequestHandler):
    def get(self):
        voices = db.GqlQuery(
            'SELECT * FROM Voice '
            'ORDER BY when DESC')
        values = {
            'voices': voices
        }
        self.response.out.write(template.render('main.html', values))
    def post(self):
        voice = Voice()
        voice.put()
        self.redirect('/')
        self.response.out.write('posted!')  

def main():
    app = webapp.WSGIApplication([
        (r'.*', MyHandler)], debug=True)
    wsgiref.handlers.CGIHandler().run(app)

if __name__ == "__main__":
    main()

Answer 1

count = db.Query().filter('when >', two_minutes_ago).filter('when <', one_minute_ago).count()

You can learn more about queries in the documentation.

To get the values of two_minutes_ago and one_minute_ago you can use the datetime module:

>>> datetime.datetime.now()
datetime.datetime(2012, 4, 14, 14, 26, 18, 343269)
>>> datetime.datetime.now() - datetime.timedelta(minutes=1)
datetime.datetime(2012, 4, 14, 14, 25, 49, 860390)

Try it out in your Python REPL to get more familiar with it.