CheckBoxField and MultipleCheckBoxField

from django.utils.translation import ugettext_lazy as _
from django.utils.encoding import smart_unicode, smart_str
from django.forms import Field, CheckboxInput, ChoiceField, MultipleHiddenInput, CheckboxSelectMultiple
from django.forms.util import ErrorList, ValidationError

class CheckboxField(Field):
    widget = CheckboxInput
    default_error_messages = {
        'invalid_choice': _(u'Select a valid choice. %(value)s is not one of the available choices.'),
    }

    def __init__(self, choices=(), required=True, widget=None, label=None, initial=None, help_text=None, *args, **kwargs):
        super(ChoiceField, self).__init__(required, widget, label, initial,  help_text, *args, **kwargs)
        self.choices = choices

    def _get_choices(self):
        return self._choices

    def _set_choices(self, value):
        # Setting choices also sets the choices on the widget.
        # choices can be any iterable, but we call list() on it because
        # it will be consumed more than once.
        self._choices = self.widget.choices = list(value)

    choices = property(_get_choices, _set_choices)

    def clean(self, value):
        """
        Validates that the input is in self.choices.
        """
        value = super(ChoiceField, self).clean(value)
        if value in EMPTY_VALUES:
            value = u''
        value = smart_unicode(value)
        if value == u'':
            return value
        if not self.valid_value(value):
            raise ValidationError(self.error_messages['invalid_choice'] % {'value': value})
        return value

    def valid_value(self, value):
        "Check to see if the provided value is a valid choice"
        for k, v in self.choices:
            if type(v) in (tuple, list):
                # This is an optgroup, so look inside the group for options
                for k2, v2 in v:
                    if value == smart_unicode(k2):
                        return True
            else:
                if value == smart_unicode(k):
                    return True
        return False
    
class MultipleCheckboxField(ChoiceField):
    hidden_widget = MultipleHiddenInput
    widget = CheckboxSelectMultiple
    default_error_messages = {
        'invalid_choice': _(u'Select a valid choice. %(value)s is not one of the available choices.'),
        'invalid_list': _(u'Enter a list of values.'),
    }

    def clean(self, value):
        """
        Validates that the input is a list or tuple.
        """
        if self.required and not value:
            raise ValidationError(self.error_messages['required'])
        elif not self.required and not value:
            return []
        if not isinstance(value, (list, tuple)):
            raise ValidationError(self.error_messages['invalid_list'])
        new_value = [smart_unicode(val) for val in value]
        # Validate that each value in the value list is in self.choices.
        for val in new_value:
            if not self.valid_value(val):
                raise ValidationError(self.error_messages['invalid_choice'] % {'value': val})
        return new_value