jquery - Confused with JSON data and normal data in Django ajax request -

i read json internet still have not got grasp of it. reading article

http://webcloud.se/log/ajax-in-django-with-jquery/

i not understood first part function using json

def xhr_test(request, format):     if request.is_ajax():         if format == 'xml':             mimetype = 'application/xml'         if format == 'json':             mimetype = 'application/javascript'         data = serializers.serialize(format, examplemodel.objects.all())         return httpresponse(data,mimetype)     # if want prevent non xhr calls     else:         return httpresponse(status=400) 

my main problems are

1. from function getting format variable
2. does format json mean data given function json or data recived json
3. can give me simple example ouput of function data = serializers.serialize(format, examplemodel.objects.all())
4. how use data when response in jquery function
5. if don't use json in above function how input , response chnage

thanks

1. from function getting format variable

in practice, there lots of ways format populated. http provides accept: header requests can use indicate preferred content-type response. on client, might use xhr.setrequestheader('accept', 'application/json') tell server want response in json format. in practice, though, few frameworks this. being django, arguments view functions set in urlconf, might craft urlconf this:

urlpatterns = patterns('',      # ...     (r'^xhr_test.(?<format>.*)$', 'path.to.xhr_test'), ) 

2 . format json mean data given function json or data recived json

this particular view doesn't @ request body, , providing response body in supplied format

4 . how use data when response in jquery function

depending on how complicated request needs be, can use jquery.getjson, pass callback regular javascript objects result parsing json. if need bit more work request right, can use jquery.parsejson process json data, , return same javascript objects.