JSON Serializing Django Models with simplejson - django

Question

I'd like to use simplejson to serialize a Django model. Django's serializer doesn't support dictionaries... and simplejson doesn't support Django Querysets. This is quite a conundrum.
In the model there's sponsors that have a Foreign Key to sponsor level, I'm trying to group all the sponsors that belong to a certain sponsor level together. Here's the code that generates the list:
from django.shortcuts import get_list_or_404
from special_event.models import Sponsor, SponsorLevel
sponsor_dict = {}
roadie_sponsors = get_list_or_404(Sponsor, level__category = SponsorLevel.ROADIE_CHOICE)
for item in roadie_sponsors:
try:
sponsor_dict[item.level.name].append(item)
except KeyError:
sponsor_dict[item.level.name] = [item]
Here's what sponsor_dict looks like once it's "made"
{
'Fan': [<Sponsor: Fan Sponsor>],
'VIP': [<Sponsor: VIP Sponsor>],
'Groupie': [<Sponsor: Groupie Sponsor>],
'Silver': [<Sponsor: Silver Sponsor>],
'Bronze': [<Sponsor: Another Bronze Sponsor>, <Sponsor: Bronze Sponsor>]
}
I only added one sponsor in each level, except for bronze, just to show how it works. All I want to do is get it "all" into JSON so jQuery can interpret it easily. Can Django's other serializers (like XML or YAML) accomplish this? Can I "extend" the Django JSON Serializer to handle dictionaries or "extend" simplejson to handle Django QuerySet objects?

Answer 1

I would go with extending simplejson. Basically, you want to plug in django's serialization when the JSON encoder encounters a QuerySet. You could use something like:
from json import dumps, loads, JSONEncoder
from django.core.serializers import serialize
from django.db.models.query import QuerySet
from django.utils.functional import curry
class DjangoJSONEncoder(JSONEncoder):
def default(self, obj):
if isinstance(obj, QuerySet):
# `default` must return a python serializable
# structure, the easiest way is to load the JSON
# string produced by `serialize` and return it
return loads(serialize('json', obj))
return JSONEncoder.default(self,obj)
# partial function, we can now use dumps(my_dict) instead
# of dumps(my_dict, cls=DjangoJSONEncoder)
dumps = curry(dumps, cls=DjangoJSONEncoder)
For more info on default method, have a look at simplejson documentation. Put that in a python module, then import dumps and you're good to go. But note that this function will only help you serializing QuerySet instances, not Model instances directly.

Answer 2

A really flexible way to serialize most structures in django is to use the serializer class found here

Answer 3

based on Clement's answer, I did this to get models into JSON as well.
def toJSON(obj):
if isinstance(obj, QuerySet):
return simplejson.dumps(obj, cls=DjangoJSONEncoder)
if isinstance(obj, models.Model):
#do the same as above by making it a queryset first
set_obj = [obj]
set_str = simplejson.dumps(simplejson.loads(serialize('json', set_obj)))
#eliminate brackets in the beginning and the end
str_obj = set_str[1:len(set_str)-2]
return str_obj