JSONType for SQLAlchemy

I wanted to save/load JSON to SQLAlchemy transparently, the same way you can with PickleType. Also I wanted to know how to do value conversion generally in SQLAlchemy. So here is a custom SQLAlchemy type: JSONType, it uses simplejson to do the actual JSON parsing/serialization.

import simplejson
from sqlalechmy.types import Text, MutableType, TypeDecorator

class JSONType(MutableType, TypeDecorator):
    impl = Text

    def __init__(self):
        super(JSONType, self).__init__()

    def process_bind_param(self, value, dialect):
        return simplejson.dumps(value)

    def process_result_value(self, value, dialiect):
        return simplejson.loads(value)

    def copy_value(self, value):
        return simplejson.loads(simplejson.dumps(value))