For most applications, simplejson.dumps() is enough. But I’m especially fond of iterators, generators, functors (objects with a `__call__()` method) and closures, dense components that express one thought well: the structure of a tree, or the rows of a database, to be sent to the browser. The routine dumps() doesn’t understand any of those things, but with a simple addition, you can plug them into your code and be on your way without headache. Dumps() just calls JSONEncoder(), and JSONEncoder has a routine for extending its functionality.
The routine is to override a method named default() (why “default?” I have no idea) and add the object types and signatures you want to send to the browser. Normally, this exists for you to provide custom “object to JSON” handlers for your objects, but there’s nothing custom about iterators, generators, functors and closures. They are native Python objects. This snippet provides the functionality needed by JSONEncoder to correctly dereference these useful Python objects and render their contents.
(Originally posted [here](http://www.elfsternberg.com/2009/05/20/fixing-an-omission-from-djangos-simplejson-iterators-generators-functors-and-closures/) )
Django supports the serializing model objects, but does not support the serializing Q object like that,
============================
q = Q(username__contains="findme")
model0.objects.filter(q)
serialize(q) # X
============================
so I wrote a little marshaller for Q, this is example,
============================
from django.contrib.auth import models as django_models
qs = django_query.Q(username__contains="spike") | django_query.Q(email__contains="spike")
_m = QMarshaller()
a = _m.dumps(qs) # a was serialized.
When call the similiar queries in page by page, you don't need to write additional code for creating same Q(s) for filtering models, just use the serialized Q as http querystring and in the next page unserialize and apply it. That is simple life.