Django snippets

from django import oldforms
from django.db import models
from django.utils.functional import curry

class SelectMultipleFieldWithDefault(oldforms.SelectMultipleField):
    def __init__(self, default_choice=None, *args, **kwargs):
        self.__default_choice = default_choice
        super(SelectMultipleFieldWithDefault, self).__init__(*args, **kwargs)
        
    def render(self, data):
        if not data and self.__default_choice:
            data = [self.__default_choice.id]
        return super(SelectMultipleFieldWithDefault, self).render(data)

class ManyToManyFieldWithDefault(models.ManyToManyField):
    def __init__(self, *args, **kwargs):
        if not kwargs.get('blank', False) and not kwargs.get('null', False):
            self.__default_choice = kwargs.get('default', None)
        else:
            self.__default_choice = None
        super(ManyToManyFieldWithDefault, self).__init__(*args, **kwargs)
        
    def get_manipulator_field_objs(self):
        if self.rel.raw_id_admin:
            return [oldforms.RawIdAdminField]
        else:
            choices = self.get_choices_default()
            return [curry(SelectMultipleFieldWithDefault, size=min(max(len(choices), 5), 15), choices=choices, default_choice=self.__default_choice)]