Chronosbox

# -*- coding: utf-8 -*-
 
from django.utils import simplejson
from django.utils.encoding import force_unicode
from django.db.models.base import ModelBase
 
class LazyJSONEncoder(simplejson.JSONEncoder):
    """ a JSONEncoder subclass that handle querysets and models objects.
    Add how handle your type of object here to use when when dump json"""
    def default(self,o):
        # this handles querysets and other iterable types
        try:
            iterable = iter(o)
        except TypeError:
            pass
        else:
            return list(iterable)
 
        # this handlers Models
        try:
            isinstance(o.__class__,ModelBase)
        except Exception:
            pass
        else:
            return force_unicode(o)
 
        return super(LazyJSONEncoder,self).default(obj)
 
def serialize_to_json(obj,*args,**kwargs):
    """ A wrapper for simplejson.dumps with defaults as:
 
    ensure_ascii=False
    cls=LazyJSONEncoder
 
    All arguments can be added via kwargs
    """
 
    kwargs['ensure_ascii'] = kwargs.get('ensure_ascii',False)
    kwargs['cls'] = kwargs.get('cls',LazyJSONEncoder)
 
 
    return simplejson.dumps(obj,*args,**kwargs)

# -*- coding: utf-8 -*-
 
from utils import serialize_to_json
from django.http import HttpResponseForbidden, HttpResponse
 
class JSONResponse(HttpResponse):
    """ JSON response class """
    def __init__(self,content='',json_opts={},mimetype="application/json",*args,**kwargs):
        """
        This returns a object that we send as json content using 
        utils.serialize_to_json, that is a wrapper to simplejson.dumps
        method using a custom class to handle models and querysets. Put your
        options to serialize_to_json in json_opts, other options are used by
        response.
        """
        if content:
            content = serialize_to_json(content,**json_opts)
        else:
            content = serialize_to_json([],**json_opts)
        super(JSONResponse,self).__init__(content,mimetype,*args,**kwargs)

(r'^$','jsonui.views.mainview'),
(r'^ajax/city/','jsonui.views.json_get_city'),

# -*- coding: utf-8 -*-
 
from django.shortcuts import render_to_response
from django.template import RequestContext
 
 
from models import City,State
from forms import CityForm
 
from utils import qdct_as_kwargs
from response import JSONResponse
 
def mainview(request):
 
    return render_to_response('base.html',{'form': CityForm() },
        context_instance=RequestContext(request))
 
def json_get_city(request):
 
    if not request.method == "POST":
        # return all cities if any filter was send
        return JSONResponse(City.objects.order_by('name'))
 
    # get cities with request.POST as filter arguments
    cities = City.objects.filter(**qdct_as_kwargs(request.POST)).order_by('name')
 
    #return JSONResponse with id and name
    return JSONResponse(cities.values('id','name'))

def qdct_as_kwargs(qdct):
kwargs={}
for k,v in qdct.items():
    kwargs[str(k)]=v
return kwargs

$(function(){
    $("#id_state").change(function(e){
        $.post(
            // url to post
            "/ajax/city/",
            // args
            {state__id:$(this).val()},
            // response callback
            function(data,text,xhrobject){
                // uncomment if you wanna to see objects on firebug console
                //console.log(data,text,xhrobject)
                $("#id_city").children().remove()
                    .append("<option selected=\"selected\" value=\"\">------</option>")
                for (i in data) {
                    i = data[i]
                    $("#id_city").append(
                        "<option value=\""+i.id+"\">"+i.name+"</option>"
                    )
                }
            })
    })
})