How to get data from Google App Engine for python with jQuery

GAE side:

import simplejson

...

class HistoryHandler(webapp.RequestHandler):

def get(self):

viewerid = self.request.get('viewerid')

query = "SELECT * FROM dbmodel where viewerid = '" + viewerid + "'"

datas = db.GqlQuery(query)

result = []

for data in datas:

r = {}

r["key"] = data.key().id()

r["unreadflag"] = data.unreadflag

result.append(r)

self.response.out.write(simplejson.dumps(result))

jQuery side:

    $.get('http://xxxxxxxx.appspot.com/historydata signed', {viewerid : viewerid}, function(results) {

      if(results.length == 0){

      ...

      }

      else{

              //when results is an object, this "i" is a hash key.

              //when results is an array, this "i" is an index.

     $.each(results, function(i, r) {

     alert(r.unreadflag);

     });

      }

    }, 'json');

P.S.

My English is not good enough.

If there is a mistake and an anxious point,teach me softly.