MultipleChoiceCommaField for Django reads and saves comma separated values

fields.py

from django import forms
from django.core.exceptions import ValidationError


class MultipleChoiceCommaField(forms.MultipleChoiceField):
    """
    Store a comma separated list of multiple choice values in a CharField/TextField
    """
    widget = forms.CheckboxSelectMultiple

    def prepare_value(self, value):
        if value and not isinstance(value, (list, tuple)):
            return value.split(",")
        return value

    def to_python(self, value):
        if not value:
            return ""
        elif not isinstance(value, (list, tuple)):
            raise ValidationError(self.error_messages['invalid_list'],
                                  code='invalid_list')
        return ",".join(smart_text(val) for val in value)

    def validate(self, value):
        value = value.split(",") if value else []
        return super(MultipleChoiceCommaField, self).validate(value)