+class JSONFormField(forms.Field):
+ default_validators = [json_validator]
+
+ def clean(self, value):
+ if value == '' and not self.required:
+ return None
+ try:
+ return json.loads(value)
+ except Exception, e:
+ raise ValidationError(u'JSON decode error: %s' % e)
+
+
+class JSONDescriptor(object):
+ def __init__(self, field):
+ self.field = field
+
+ def __get__(self, instance, owner):
+ if instance is None:
+ raise AttributeError # ?
+
+ if self.field.name not in instance.__dict__:
+ json_string = getattr(instance, self.field.attname)
+ instance.__dict__[self.field.name] = json.loads(json_string)
+
+ return instance.__dict__[self.field.name]
+
+ def __set__(self, instance, value):
+ instance.__dict__[self.field.name] = value
+ setattr(instance, self.field.attname, json.dumps(value))
+
+ def __delete__(self, instance):
+ del(instance.__dict__[self.field.name])
+ setattr(instance, self.field.attname, json.dumps(None))
+
+
+class JSONField(models.TextField):
+ default_validators = [json_validator]
+
+ def get_attname(self):
+ return "%s_json" % self.name
+
+ def contribute_to_class(self, cls, name):
+ super(JSONField, self).contribute_to_class(cls, name)
+ setattr(cls, name, JSONDescriptor(self))
+ models.signals.pre_init.connect(self.fix_init_kwarg, sender=cls)
+
+ def fix_init_kwarg(self, sender, args, kwargs, **signal_kwargs):
+ if self.name in kwargs:
+ kwargs[self.attname] = json.dumps(kwargs.pop(self.name))
+
+ def formfield(self, *args, **kwargs):
+ kwargs["form_class"] = JSONFormField
+ return super(JSONField, self).formfield(*args, **kwargs)
+
+